LTM8062/LTM8062A
1
8062fd
For more information www.linear.com/LTM8062
Typical applicaTion
FeaTures DescripTion
32VIN, 2A µModule Power
Tracking Battery Chargers
The LT M
®
8062/LTM8062A are complete 32VIN, 2A
µModule
®
power tracking battery chargers. The LTM8062/
LTM8062A provide a constant-current/constant-voltage
charge characteristic, a 2A maximum charge current, and
employ a 3.3V float voltage feedback reference, so any
desired battery float voltage up to 14.4V for the LTM8062
and up to 18.8V for the LTM8062A can be programmed
with a resistor divider.
The LTM8062/LTM8062A employ an input voltage regula-
tion loop, which reduces charge current if the input volt-
age falls below a programmed level, set with a resistor
divider. When the LTM8062/LTM8062A are powered by a
solar panel, this input regulation loop is used to maintain
the panel at peak output power. The LTM8062/LTM8062A
also feature preconditioning trickle charge, bad battery
detection, a choice of termination schemes and automatic
restart.
The LTM8062/LTM8062A are packaged in a thermally en-
hanced, compact (9mm × 15mm × 4.32mm) over-molded
land grid array (LGA) package suitable for automated
assembly by standard surface mount equipment. The
LTM8062/LTM8062A are RoHS compliant.
L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
2A LiFePO4 µModule Battery Charger
applicaTions
n Complete Battery Charger System
n Input Supply Voltage Regulation Loop for Peak
Power Tracking in MPPT (Maximum Peak Power
Tracking) Solar Applications
n Resistor Programmable Float Voltage Up to 14.4V
on the LTM8062 and 18.8V on the LTM8062A
n Wide Input Voltage Range: 4.95V to 32V
(40V Abs Max)
n 2A Charge Current
n Accommodates Li-Ion/Polymer, LiFePO4, SLA
n Integrated Input Reverse Voltage Protection
n User Selectable Termination: C/10 or Termination
Timer
n 0.75% Float Voltage Reference Accuracy
n 9mm × 15mm × 4.32mm LGA Package
n Industrial Handheld Instruments
n 12V to 24V Automotive and Heavy Equipment
n Desktop Cradle Chargers
n Solar Power Battery Charging
Charge Current vs Battery Voltage
8062 TA01a
LTM8062
GND
VINA
VIN
VINREG
RUN
TMR
NTC
VIN
6V TO 32V BAT
BIAS
CHRG
FAULT
ADJ
4.7µF
274k
2.87M
1-CELL
LiFePO4
(3.6V)
BATTERY VOLTAGE (V)
0
0
CHARGING CURRENT (mA)
2
2500
8062 TA01b
1 3 4
1000
500
1500
2000 NORMAL CHARGING
PRECONDITION
TERMINATION
LTM8062/LTM8062A
2
8062fd
For more information www.linear.com/LTM8062
pin conFiguraTionabsoluTe MaxiMuM raTings
VINA, VIN ...................................................................40V
VINREG, RUN, CHRG, FA U LT ......................VIN + 0.5, 40V
TMR, NTC ................................................................2.5V
BAT (LTM8062) .........................................................15V
BAT (LTM8062A) ......................................................20V
BIAS ..........................................................................10V
ADJ .............................................................................5V
Maximum Internal Operating Temperature
(Note 2) ................................................................. 125°C
Maximum Body Solder Temperature ..................... 245°C
(Note 1)
A B C D E F
BANK 1
FAULTADJBIAS
BANK 2BAT
GND
G H J K L
7
6
5
4
3
2
1
BANK 3
BANK 4
VIN
VINA
LGA PACKAGE
77-LEAD (15mm × 9mm × 4.32mm)
TOP VIEW
CHRG GND
TMRNTC RUN VINREG
TJMAX = 125°C, θJA = 17.0°C/W, θJCbottom = 6.1°C/W,
θJCtop = 16.2°C/W, θJB = 11.2°C/W, WEIGHT = 1.7g
θ VALUES DETERMINED PER JEDEC 51-9, 51-12
orDer inForMaTion
LEAD FREE FINISH TRAY PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTM8062EV#PBF LTM8062EV#PBF LTM8062V 77-Lead (15mm × 9mm × 4.32mm) LGA –40°C to 125°C
LTM8062IV#PBF LTM8062IV#PBF LTM8062V 77-Lead (15mm × 9mm × 4.32mm) LGA –40°C to 125°C
LTM8062AEV#PBF LTM8062AEV#PBF LTM8062AV 77-Lead (15mm × 9mm × 4.32mm) LGA –40°C to 125°C
LTM8062AIV#PBF LTM8062AIV#PBF LTM8062AV 77-Lead (15mm × 9mm × 4.32mm) LGA –40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
LTM8062/LTM8062A
3
8062fd
For more information www.linear.com/LTM8062
elecTrical characTerisTics
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTM8062E/LTM8062AE are guaranteed to meet performance
specifications from 0°C to 125°C internal. Specifications over the full
–40°C to 125°C internal operating temperature range are assured by
design, characterization and correlation with statistical process controls.
The LTM8062I/LTM8062AI are guaranteed to meet specifications over
the full –40°C to 125°C internal operating temperature range. Note that
The l denotes the specifications which apply over the full internal
operating temperature range, otherwise specifications are at TA = 25°C. RUN = 2V.
the maximum internal temperature is determined by specific operating
conditions in conjunction with board layout, the rated package thermal
resistance and other environmental factors.
Note 3: This parameter is valid for programmed output battery float
voltages ≤ 4.2V. For other float voltages, VIN Start is 3.3V above the
programmed output battery float voltage. This parameter is guaranteed by
design, characterization, and correlation with statistical process controls.
Note 4: The maximum BAT charging current is reduced by thermal
foldback. See the Typical Performance Characteristics for details.
PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Maximum Operating Voltage 32 V
VIN Start Voltage VBAT = 4.2V (Note 3) 7.5 V
VIN OVLO Threshold VIN Rising 32 35 40 V
VIN OVLO Hysteresis 1 V
VIN UVLO Threshold VIN Rising 4.6 4.95 V
VIN UVLO Hysteresis 0.3 V
VINA to VIN Diode Forward Voltage Drop VINA Current = 2A 0.55 V
Maximum BAT Float Voltage LTM8062
LTM8062A
14.7
19.3
V
V
Input Supply Current Standby Mode
RUN = 0, VINREG = 15V
85
18
µA
µA
Maximum BAT Charging Current (Note 4) 1.8 2.1 A
ADJ Float Reference Voltage
l
3.275
3.25
3.3 3.325
3.34
V
V
ADJ Recharge Threshold Voltage Threshold Relative to ADJ Float Reference 82.5 mV
ADJ Precondition Threshold Voltage ADJ Rising 2.3 V
ADJ Precondition Threshold Hysteresis Voltage Relative to ADJ Precondition Threshold 95 mV
ADJ Input Bias Current Charging Terminated
CV Operation
65
110
nA
nA
VINREG Reference Voltage ADJ = 3V, IBAT = 1A l2.61 2.7 2.83 V
VINREG Bias Current VINREG = 2.7V 27 µA
NTC Range Limit (High) Voltage VNTC Rising 1.25 1.36 1.45 V
NTC Range Limit (Low) Voltage VNTC Falling 0.27 0.29 0.315 V
NTC Disable Impedance 250 500 kΩ
NTC Bias Current VNTC = 0.8V 45 53 µA
NTC Threshold Hysteresis For Both High and Low Range Limits 20 %
RUN Threshold Voltage VRUN Rising 1.15 1.20 1.25 V
RUN Hysteresis Voltage 120 mV
RUN Input Bias Current –10 nA
CHRG, FAULT Output Low Voltage 10mA Load 0.4 V
TMR Charge/Discharge Current 25 µA
TMR Disable Threshold Voltage 0.25 V
Operating Frequency 0.85 1 1.15 MHz
LTM8062/LTM8062A
4
8062fd
For more information www.linear.com/LTM8062
Typical perForMance characTerisTics
Efficiency vs IBAT, 14.4V Float Efficiency vs IBAT, 18.8V Float ADJ Float Voltage vs Temperature
IBIAS vs IBAT, 4.2V Float IBIAS vs IBAT, 7.2V Float IBIAS vs IBAT, 8.4V Float
Efficiency vs IBAT, 4.2V Float Efficiency vs IBAT, 7.2V Float Efficiency vs IBAT, 8.4V Float
TA = 25°C, unless otherwise noted.
IBAT (mA)
0
70
EFFICIENCY (%)
72
74
76
1000
84
8062 G01
500 1500 2000
78
80
82 VINA = 12V
VINA = 24V
IBAT (mA)
0
80
EFFICIENCY (%)
81
82
83
1000
87
8062 G02
500 1500 2000
84
85
86 VINA = 12V
VINA = 24V
IBAT (mA)
0
81
EFFICIENCY (%)
82
83
84
1000
88
8062 G03
500 1500 25002000
85
86
87
VINA = 12V
VINA = 24V
IBAT (mA)
0
82
EFFICIENCY (%)
83
84
85
1000
90
8062 G04
500 1500 2000
86
87
88
89
VINA = 24V
TEMPERATURE (°C)
–50
3.265
ADJ FLOAT VOLTAGE (V)
0
3.280
8062 G05
–25 25 100 12550 75
3.270
3.275
IBAT (mA)
0
0
IBIAS (mA)
5
10
15
1000
25
8062 G06
500 1500 2000
20
VINA = 12V
VINA = 24V
IBAT (mA)
0
0
I
BIAS
(mA)
5
10
15
1000
45
8062 G07
500 1500 2000
20
25
30
35
40
VINA = 12V
VINA = 24V
IBAT (mA)
0
0
I
BIAS
(mA)
5
10
15
1000
50
45
8062 G08
500 1500 2000
20
25
30
35
40
VINA = 24V
VINA = 12V
IBAT (mA)
0
86
EFFICIENCY (%)
87
88
89
1000
93
8062 G23
500 1500
2000
90
91
92
VINA = 24V
LTM8062/LTM8062A
5
8062fd
For more information www.linear.com/LTM8062
Typical perForMance characTerisTics
Input Current vs IBAT, 14.4V Float
Input Current vs IBAT, 18.8V Float IQ vs VINA, RUN = 0V, VINREG Open Maximum IBAT vs ADJ
Input Current vs IBAT, 4.2V Float
Input Current vs IBAT, 7.2V Float Input Current vs IBAT, 8.4V Float
IBIAS vs IBAT, 14.4V Float IBIAS vs IB AT, 18.8V Float
TA = 25°C, unless otherwise noted.
IBAT (mA)
0
0
IBIAS (mA)
5
10
15
1000
45
8062 G09
500 1500 2000
20
25
30
35
40
VINA = 24V
IBAT (mA)
0
0
INPUT CURRENT (mA)
100
200
1000
900
800
8062 G10
500 1500 2000
300
400
500
600
700
VINA = 12V
VINA = 24V
IBAT (mA)
0
0
INPUT CURRENT (mA)
200
1000
1400
1200
8062 G11
500 1500 2000
400
600
800
1000
VINA = 12V
VINA = 24V
IBAT (mA)
0
0
INPUT CURRENT (mA)
200
1000
1600
1400
1200
8062 G12
500 1500 25002000
400
600
800
1000
VINA = 12V
VINA = 24V
IBAT (mA)
0
0
INPUT CURRENT (mA)
200
1000
1400
1200
8062 G13
500 1500 2000
400
600
800
1000
VINA = 24V
VINA (V)
0
0
I
Q
(µA)
20
250
200
8062 G14
10 30 40
50
100
150
ADJ VOLTAGE (V)
0
0
MAXIMUM IBAT (mA)
2
2500
2000
8062 G15
10.5 2.5
1.5 3 3.5
500
1000
1500
IBAT (mA)
0
800
1000
1200
600
400
0500 1000 1500
200
1400
VINA = 24V
IBAT (mA)
0
0
I
BIAS
(mA)
5
10
15
1000
50
45
8062 G24
500 1500
2000
20
25
30
35
40
VINA = 24V
LTM8062/LTM8062A
6
8062fd
For more information www.linear.com/LTM8062
Typical perForMance characTerisTics
Temperature Rise vs IBAT,
14.4V Float Voltage
Temperature Rise vs IBAT,
18.8V Float Voltage
VIN Standby Mode Current
vs Temperature
Temperature Rise vs IB AT,
7.2V Float Voltage
Temperature Rise vs IBAT,
8.4V Float Voltage
IBAT (mA)
0
0
TEMPERATURE RISE (°C)
5
1000
30
8062 G19
500 1500 2000
10
15
20
25
VINA = 24V
VINA = 12V
IBAT (mA)
0
0
TEMPERATURE RISE (°C)
5
1000
30
8062 G20
500 1500 2000
10
15
20
25
VINA = 12V
VINA = 24V
IBAT (mA)
0
0
TEMPERATURE RISE (°C)
5
1000
40
8062 G21
500 1500 2000
10
15
20
25
30
35
VINA = 24V
TEMPERATURE (°C)
–50
0
V
IN
STANDBY MODE CURRENT (mA)
50
6
8062 G22
0 100
1
2
3
4
5
VINA = 24V
VINA = 12V
TA = 25°C, unless otherwise noted.
IBAT (mA)
0
0
TEMPERATURE RISE (°C)
5
10
1000
45
40
8062 G26
500 1500
2000
15
20
25
30
35
VINA = 24V
Maximum IBAT vs VINREG
Maximum Charge Current
vs Temperature
Temperature Rise vs IB AT,
4.2V Float Voltage
VINREG (V)
2
0
MAXIMUM I
BAT
(mA)
2500
2000
8062 G16
2.5 3 3.5
500
1000
1500
TEMPERATURE (°C)
–40 –20
0
CHARGE CURRENT (mA)
60
2000
1600
1200
8062 G17
0 80
20 40 120100
400
800
IBAT (mA)
0
0
TEMPERATURE RISE (°C)
5
1000
25
8062 G18
500 1500 2000
10
15
20
VINA = 12V
VINA = 24V
Minimum VIN vs VBAT 1.7A Load
VBAT (V)
0
0
VIN (V)
10
25
8062 G27
5 15 20
5
10
15
20
LTM8062/LTM8062A
7
8062fd
For more information www.linear.com/LTM8062
pin FuncTions
GND (Bank 1, Pin L7): Power and Signal Ground Return.
BAT (Bank 2): Battery Charge Current Output Bus. The
charge function operates to achieve the final float voltage
at this pin. The auto-restart feature initiates a new charging
cycle when the voltage at the ADJ pin falls 2.5% below
the float voltage. Once the charge cycle is terminated, the
input bias current of the BAT pin is reduced to minimize
battery discharge while the charger remains connected.
VINA (Bank 3): Anode of input reverse protection Schottky
diode. Connect the input power here if input reverse volt-
age protection is desired.
VIN (Bank 4): Charger Input Supply. Decouple with at least
4.7µF to GND. Connect the input power here if no input
reverse voltage protection is needed.
BIAS (Pin G7): The BIAS pin connects to the internal
power bus. In most cases connect to VBAT. If this is not
desirable, connect to a power source greater than 2.8V
and less than 10V.
CHRG (Pin K7): Open-Collector Charger Status Output;
typically pulled up through a resistor to a reference
voltage. This status pin can be pulled up to voltages as
high as VIN and can sink currents up to 10mA. During
a battery charging cycle, CHRG is pulled low. When the
charge current falls below C/10, the CHRG pin becomes
high impedance. If the internal timer is used for termina-
tion, the pin stays low during the charging cycle until the
charge current drops below a C/10 rate, approximately
200mA, even though the charger will continue to top off
the battery until the end-of-charge timer terminates the
charge cycle. A temperature fault also causes this pin to
be pulled low (see the Applications Information section).
NTC (Pin H6): Battery Temperature Monitor Pin. This pin
is the input to the NTC (negative temperature coefficient)
thermistor temperature monitoring circuit. This function is
enabled by connecting a 10kΩ, B = 3380 NTC thermistor
from the NTC pin to ground. The pin sources 50μA, and
monitors the voltage across the 10kΩ thermistor. When the
voltage on this pin is above 1.36V (T < 0°C) or below 0.29V
(T > 40°C), charging is disabled and the CHRG and FAULT
pins are both pulled low. If the internal timer termination is
being used, the timer is paused, suspending the charging
cycle. Charging resumes when the voltage on NTC returns
to within the 0.29V to 1.36V active region. There is approxi-
mately 5°C of temperature hysteresis associated with each
of the temperature thresholds. The temperature monitoring
function remains enabled while thermistor resistance to
ground is less than 250kΩ. If this function is not desired,
leave the NTC pin unconnected.
ADJ (Pin H7): Battery Float Voltage Feedback Input. The
charge function operates to achieve a final float voltage of
3.3V on this pin. The output battery float voltage (VBAT(FLT))
is programmed using a resistor divider. VBAT(FLT) can be
programmed up to 14.4V. The auto-restart feature initi-
ates a new charging cycle when the voltage at the ADJ
pin falls 2.5% below the float voltage reference. The ADJ
pin input bias current is 110nA. Using a resistor divider
with an equivalent input resistance at the ADJ pin of 250k
compensates for input bias current error. Required resistor
values to program desired VBAT(FLT) follow the equations:
R1=VBAT(FLT) •2.5 •105
3.3 (Ω)
R2 =R1•2.5 •105
R1−(2.5 •105)(Ω)
R1 is connected from BAT to ADJ, and R2 is connected
from ADJ to ground.
FAULT (Pin J7): Open-Collector Fault Status Output; typi-
cally pulled up through a resistor to a reference voltage.
This status pin can be pulled up to voltages as high as
VIN and can sink currents up to 10mA. This pin indicates
charge cycle fault conditions during a battery charging
cycle. A temperature fault causes this pin to be pulled
low. If the internal timer is used for termination, a bad bat-
tery fault also causes this pin to be pulled low. If no fault
conditions exist, the FAULT pin remains high impedance
(see the Applications Information section).
TMR (Pin J6): End-Of-Cycle Timer Programming Pin.
If a timer-based charge termination is desired, connect
a capacitor from this pin to ground. Full charge end-of
cycle time (in hours) is programmed with this capacitor
following the equation:
tEOC = CTIMER • 4.4 • 106
A bad battery fault is generated if the battery does not
reach the precondition threshold voltage within one-eighth
of tEOC, or:
tPRE = CTIMER • 5.5 • 105
LTM8062/LTM8062A
8
8062fd
For more information www.linear.com/LTM8062
block DiagraM
8062 BD
VINA
8.2µH SENSE
RESISTOR
10µF (LTM8062)
2.2µF (LTM8062A)
0.1µF
0.1µF
RUN
VINREG
ADJ
TMR
NTC
BIAS
ADJ
GND FAULT CHRG
VIN
BAT
CURRENT
MODE
BATTERY
MANAGEMENT
CONTROLLER
INTERNAL
COMPENSATION
100k
pin FuncTions
A 0.68μF capacitor is often used, which generates a timer
EOC at three hours, and a precondition limit time of 22.5
minutes. If a timer-based termination is not desired, the
timer function can be disabled by connecting the TMR
pin to ground. With the timer function disabled, charging
terminates when the charge current drops below a C/10
rate, approximately 200mA.
VINREG (Pin L6): Input Voltage Regulation Reference. The
maximum charge current is reduced when this pin is below
2.7V. There is a 100k resistor to GND. Connecting a resis-
tor from VIN to this pin sets the minimum operational VIN
voltage. This is typically used to program the peak power
voltage for a solar panel. The LTM8062/LTM8062A servo
the maximum charge current required to maintain the
programmed operational VIN voltage, through maintain-
ing the voltage on VINREG at or above 2.7V. If the voltage
regulation feature is not used, connect the pin to VIN.
RUN (Pin K6): Precision Threshold Enable Input Pin. The
RUN threshold is 1.25V (rising), with 120mV of input hys-
teresis. When in shutdown mode, all charging functions are
disabled. The precision threshold allows use of the RUN
pin to incorporate UVLO functions. If the RUN pin is pulled
below 0.4V, the IC enters a low current shutdown mode
where the VIN pin current is reduced to 15μA. Typical RUN
pin input bias current is 10nA. If the shutdown function is
not desired, connect the pin to the VIN pin.
LTM8062/LTM8062A
9
8062fd
For more information www.linear.com/LTM8062
The LTM8062/LTM8062A are complete monolithic, mid-
power, power tracking battery chargers, addressing
high input voltage applications with solutions that use a
minimum of external components. The products can be
programmed for float voltages between 3.3V and 14.4V
(LTM8062) or between 3.3V and 18.8V (LTM8062A) with
just two external resistors, operating under a 1MHz fixed
frequency, average current mode step-down architecture. A
2A power Schottky diode is integrated within the μModule
charger for reverse input voltage protection. A wide input
range allows the operation to full charge from an input
voltage up to 32V. A precision threshold on the RUN pin
allows the implementation of a UVLO feature by using a
simple resistor network. The charger can also be put into
a low current shutdown mode, in which the input supply
bias is reduced to only 15μA.
The LTM8062/LTM8062A employ an input voltage regula-
tion loop, which reduces charge current if a monitored
input voltage falls below a programmed level at the VINREG
pin. There is a 1% 100k resistor to GND at this pin. When
the LTM8062/LTM8062A are powered by a solar panel,
the input regulation loop is used to maintain the panel at
peak output power. The LTM8062/LTM8062A automatically
enter a battery precondition mode if the sensed battery
voltage is very low. In this mode, the charge current is
reduced to 300mA. Once the battery voltage climbs above
the internally set precondition threshold (2.3V at the ADJ
pin), the μModule charger automatically increases the
maximum charge current to the full programmed value.
The LTM8062/LTM8062A can use a charge current based
C/10 termination scheme, which ends a charge cycle
when the battery charge current falls to one-tenth the
programmed charge current. The LTM8062/LTM8062A
also contain an internal charge cycle control timer, for
timer-based termination. When using the internal timer,
the charge cycle can continue beyond the C/10 level to
top-off the battery. The charge cycle terminates when
the programmed time elapses, about three hours for a
0.68µF timer capacitor. The CHRG status pin continues
to signal charging at a C/10 or greater rate, regardless of
which termination scheme is used. When the timer-based
scheme is used, the LTM8062/LTM8062A also support bad
battery detection, which triggers a system fault if a battery
stays in precondition mode for more than one-eighth of
the total programmed charge cycle time.
Once charging terminates and the LTM8062/LTM8062A are
not actively charging, the charger automatically enters a
low current standby mode in which supply bias currents
are reduced to 85μA. If the battery voltage drops 2.5%
from the full charge float voltage, the LTM8062/LTM8062A
engage an automatic charge cycle restart. The IC also au-
tomatically restarts a new charge cycle after a bad-battery
fault once the failed battery is removed and replaced with
another battery. The LTM8062/LTM8062A contain a bat-
tery temperature monitoring circuit. This feature, using a
thermistor, monitors battery temperature and will not allow
charging to begin, or will suspend charging, and signal
a fault condition if the battery temperature is outside a
safe charging range. The LTM8062/LTM8062A contain
two digital open-collector outputs, CHRG and FAULT,
which provide charger status and signal fault conditions.
These binary coded pins signal battery charging, standby
or shutdown modes, battery temperature faults and bad
battery faults. For reference, C/10 and TMR based charg-
ing cycles are shown in Figures 1 and 2.
operaTion
LTM8062/LTM8062A
10
8062fd
For more information www.linear.com/LTM8062
operaTion
Figure 1. Typical C/10 Terminated Charge Cycle (TMR Grounded, Time Not to Scale)
Figure 2. Typical EOC (Timer-Based) Terminated Charge Cycle
(Capacitor Connected to TMR, Time Not to Scale)
8062 F01
BATTERY VOLTAGE
BATTERY CHARGE
CURRENT
RUN
CHRG
FAULT
MAXIMUM CHARGE CURRENT
PRECONDITION CURRENT
C/10
0 AMPS
FLOAT VOLTAGE
RECHARGE THRESHOLD
PRECONDITION THRESHOLD
1
0
1
0
0
1
8062 F02
BATTERY VOLTAGE
BATTERY CHARGE
CURRENT
RUN
CHRG
FAULT
MAXIMUM CHARGE CURRENT
PRECONDITION CURRENT
C/10 CURRENT
AUTOMATIC
RESTART
FLOAT VOLTAGE
RECHARGE THRESHOLD
PRECONDITION THRESHOLD
1
0
1
0
0
< tEOC/8
tEOC
1
LTM8062/LTM8062A
11
8062fd
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VIN Input Supply
The LTM8062/LTM8062A are biased directly from the
charger input supply through the VIN pin. This pin pro-
vides large switched currents, so a high quality low ESR
decoupling capacitor is recommended to minimize volt-
age glitches on VIN. 4.7μF is typically adequate for most
charger applications.
Reverse Protection Diode
The LTM8062/LTM8062A integrate a high voltage power
Schottky diode to provide input reverse voltage protec-
tion. The anode of this diode is connected to VINA, and
the cathode is connected to VIN. There is a small amount
of capacitance at each end; please see the Block Diagram.
The integrated diode can also be used to block battery
discharge leakage paths. The LTM8062/LTM8062A switch
and drive circuitry are designed to stand off some reverse
voltage from BAT to VIN, but leakage paths exist that can
put a small load on the battery if VIN falls below BAT.
Specifically, the RUN pin has a small bias current and
there is a 100k resistor tied to VINREG to GND. If either
of these pins is connected to VIN when it is below BAT,
it can present a small but finite discharge current to the
battery. This discharge current may be blocked by the
integrated Schottky diode if the RUN and VINREG circuits
are tied to VINA.
Input Supply Voltage Regulation
The LTM8062/LTM8062A contain a voltage monitor pin
that enables programming a minimum operational volt-
age. There is a 1% 100k resistor from VINREG to GND.
Connecting a resistor from VIN to the VINREG pin enables
programming of minimum input supply voltage, typically
used to program the peak power voltage for a solar panel.
Maximum charge current is reduced when the VINREG pin
is below the regulation threshold of 2.7V.
If the VINREG function is not used, and if the input supply
cannot provide enough power to satisfy the requirements
of an LTM8062/LTM8062A charger, the input supply voltage
For most applications, the design process is straight
forward, summarized as follows:
1. Look at Table 1 and find the row that has the desired
input voltage range and battery float voltage.
2. Apply the recommended CIN and RADJ values.
3. Connect BIAS as indicated.
While these component combinations have been tested
for proper operation, it is incumbent upon the user to
verify proper operation over the intended system’s line,
load and environmental conditions. Bear in mind that the
maximum output current is limited by junction tempera-
ture, the relationship between the input and output voltage
magnitude and polarity and other factors. Please refer to
the graphs in the Typical Performance Characteristics
section for guidance.
Table 1. Recommended Component Values and Configuration
(TA = 25°C)
VIN RANGE (V)* VBAT (V) CIN
RADJ1
TOP
(kΩ)
RADJ2
BOTTOM
(kΩ)
6 to 32 3.6 4.7µF 1206 X7R 50V 274 2870
6 to 32 4.1 4.7µF 1206 X7R 50V 312 1260
6 to 32 4.2 4.7µF 1206 X7R 50V 320 1150
6.25 to 32 4.7 4.7µF 1206 X7R 50V 357 835
9.5 to 32 7.05 4.7µF 1206 X7R 50V 530 464
9.75 to 32 7.2 4.7µF 1206 X7R 50V 549 459
11 to 32 8.2 4.7µF 1206 X7R 50V 626 417
11.5 to 32 8.4 4.7µF 1206 X7R 50V 642 412
12.75 to 32 9.4 4.7µF 1206 X7R 50V 715 383
16.5 to 32 12.3 4.7µF 1206 X7R 50V 942 344
17 to 32 12.6 4.7µF 1206 X7R 50V 965 340
18.25 to 32 13.5 4.7µF 1206 X7R 50V 1020 328
19 to 32 14.08 4.7µF 1206 X7R 50V 1090 332
19.5 to 32 14.42 4.7µF 1206 X7R 50V 1110 328
23 to 32 16.4 4.7µF 1206 X7R 50V 1240 312
23.5 to 32 16.8 4.7µF 1206 X7R 50V 1270 309
26 to 32 18.8 4.7µF 1206 X7R 50V 1420 301
*Operating range, VIN must be 3.3V above VBAT to start. Input bulk
capacitance is required.
LTM8062/LTM8062A
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Figure 3. Resistive Divider Sets Minimum VIN
applicaTions inForMaTion
will collapse. A minimum operating supply voltage can
thus be programmed by monitoring the supply through
a resistor divider, such that the desired minimum voltage
corresponds to 2.7V at the VINREG pin. The LTM8062/
LTM8062A servo the maximum output charge current to
maintain the voltage on VINREG at or above 2.7V.
Programming of the desired minimum voltage is accom-
plished by connecting a resistor as shown in Figure 3.
RIN =100VIN – 270
2.7 k
If the voltage regulation feature is not used, connect the
VINREG pin to VIN.
physically located far from the battery and the added line
impedance may interfere with the control loop. Case 2:
the battery ESR is very small or very large; the LTM8062/
LTM8062A controller is designed for a wide range, but some
battery packs have an ESR outside of this range. Case3:
there is no battery at all. As the charger is designed to
work with the ESR of the battery, the output may oscillate
if no battery is present.
The optimum ESR is about 100mΩ, but ESR values both
higher and lower will work. Table 2 shows a sample of
parts successfully tested by Linear Technology:
Table 2
PART NUMBER DESCRIPTION MANUFACTURER
16TQC22M 22µF, 16V, POSCAP Sanyo
35SVPD18M 18µF, 35V, OS-CON Sanyo
TPSD226M025R0100 22µF, 25V Tantalum AVX
T495D226K025AS 22µF, 25V, Tantalum Kemet
TPSC686M006R0150 68µF, 6V, Tantalum AVX
TPSB476M006R0250 47µF, 6V, Tantalum AVX
APXE100ARA680ME61G 68µF, 10V Aluminum Nippon Chemicon
APS-150ELL680MHB5S 68µF, 25V Aluminum Nippon Chemicon
If system constraints preclude the use of electrolytic ca-
pacitors, a series R-C network may be used. Use a ceramic
capacitor of at least 22µF and an equivalent resistance of
100mΩ. An example of this is shown in the Typical Ap-
plications section.
MPPT Temperature Compensation
A typical solar panel is comprised of a number of series-
connected cells, each cell being a forward-biased p-n junc-
tion. As such, the open-circuit voltage (VOC) of a solar cell
has a temperature coefficient that is similar to a common
p-n diode, or about –2mV/°C. The peak power point voltage
(VMP) for a crystalline solar panel can be approximated as
a fixed voltage below VOC, so the temperature coefficient
for the peak power point is similar to that of VOC.
Panel manufacturers typically specify the 25°C values for
VOC, VMP, and the temperature coefficient for VOC, making
determination of the temperature coefficient for VMP of a
typical panel straight forward. The LTM8062/LTM8062A
employs a feedback network to program the VIN input
regulation voltage. Manipulation of the network makes for
VIN
VINREG
8062 F03
LTM8062
INPUT SUPPLY
RIN
BIAS Pin Considerations
The BIAS pin is used to provide drive power for the in-
ternal power switching stage and operate other internal
circuitry. For proper operation, it must be powered by at
least 2.8V and no more than the absolute maximum rat-
ing of 10V. In most applications, connect BIAS to BAT. If
there is no BIAS supply available or the battery voltage is
below 2.8V, the internal switch requires more headroom
from VIN for proper operation. Please refer to the Typical
Performance Characteristics curves for minimum start and
running requirements under various battery conditions.
When charging a 2-cell battery using a relatively high
input voltage, the LTM8062/LTM8062A power dissipation
can be reduced by connecting BIAS to a voltage between
2.8V and 3.3V.
Output Capacitance
In many applications, the internal BAT capacitance of the
LTM8062/LTM8062A is sufficient for proper operation.
There are cases, however, where it may be necessary to
add capacitance or otherwise modify the output imped-
ance of the LTM8062/LTM8062A. Case 1: the µModule is
LTM8062/LTM8062A
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efficient implementation of various temperature compensa-
tion schemes for a maximum peak power tracking (MPPT)
application. As the temperature characteristic for a typical
solar panel VMP voltage is highly linear, a simple solution
for tracking that characteristic can be implemented using a
Linear Technology LM234 3-terminal temperature sensor.
This creates an easily programmable, linear temperature
dependent characteristic.
In the circuit shown in Figure 4,
100VMP 25°C
(
)
VINREG
–100
1– 1 0000 0 •0.0677
VINREG •RSET
kΩ
RSET =100 1
TC•4405 +0.0677
VINREG
–
RIN =
VMP 25°C
(
)
TC•4405•VINREG
kΩ
where TC = temperature coefficient (in V/°C), and
VMP(25°C) = maximum power voltage at 25°C.
Figure 4. MPPT Temperature Compensation Network
VINREG
8062 F04
LTM8062
LINEAR
TECHNOLOGY
LM234
RIN VIN
VIN
V+
V–R
RSET
As the temperature coefficient for VMP is similar to that
of VOC, the specified temperature coefficient for VOC
(TC) of –78mV/°C and the specified peak power voltage
(VMP(25°C)) of 17.6V can be inserted into the equations to
calculate the appropriate resistor values for the temperature
compensation network in Figure 4. Initially, determine the
RSET value using the following equation:
RSET =100 1
–78mV/°C•4405
+0.0677
2.7 –
17.6
–78mV / °C•4405•2.7
kΩ ⇒4.12kΩ
Then, RIN can be determined using the calculated RSET
value:
RIN =
100 •17.6V
2.7 –100
1– 100000 •0.0677
2.7 •4120
kΩ ⇒1400kΩ
Battery Voltage Temperature Compensation
Some battery chemistries have charge voltage require-
ments that vary with temperature. Lead-acid batteries in
particular experience a significant change in charge volt-
age requirements as temperature changes. For example,
manufacturers of large lead-acid batteries recommend
a float charge of 2.25V/cell at 25°C. This battery float
voltage, however, has a temperature coefficient which is
typically specified at –3.3mV/°C per cell.
In a manner similar to the MPPT temperature correction
outlined previously, implementation of linear battery charge
voltage temperature compensation can be accomplished by
incorporating a Linear Technology LM234 into the output
feedback network. For example, a 6-cell lead acid battery
has a float charge voltage that is commonly specified at
2.25V/cell at 25°C, or 13.5V, and a –3.3mV/°C per cell tem-
perature coefficient, or –19.8mV/°C. Using the feedback
For example, given a common 36-cell solar panel that has
the following specified characteristics:
Open Circuit Voltage (VOC) = 21.7V
Maximum Power Voltage (VMP) = 17.6V
Open-Circuit Voltage Temperature Coefficient (VOC)
= –78mV/°C
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Figure 5. Lead-Acid 6-Cell Float Charge Voltage vs Temperature
with a –19.8mV/°C Temperature Coefficient Using LM234 with
the Feedback Network
network shown in Figure 5, with the desired temperature
coefficient (TC) and 25°C float voltage (VFLOAT (25°C))
specified, and using a convenient value of 2.4k for RSET,
necessary resistor values follow the relations:
RFB1 = –RSET • (TC • 4405)
= –2.4k • (–0.0198 • 4405) ⇒ 210kΩ
RFB2 =
R
FB1
VFLOAT(25°C)+RFB1 •(0.0674 /RSET )
VFB
-
1
=210k
13.5+210k •(0.0674 / 2.4k)
3.3 -1
⇒43kΩ
RFB3 = 250k – RFB1||RFB2
= 250k – 210k||43k ⇒ 215kΩ
(see the Battery Float Voltage Programming section)
While the circuit in Figure 5 creates a linear tempera-
ture characteristic that follows a typical –3.3mV/°C per
cell lead-acid specification, the theoretical float charge
voltage characteristic is slightly nonlinear. This nonlinear
characteristic follows the relation:
VFLOAT = 4 • 10–5 (T2) – 6 • 10–3(T) + 2.375
(with a 2.18V minimum)
where T = temperature in °C. A thermistor-based network
can be used to approximate the nonlinear ideal tempera-
ture characteristic across a reasonable operating range,
as shown in Figure 6.
Figure 6. Thermistor-Based Temperature Compensation Network
Programs VFLOAT to Closely Match Ideal Lead-Acid Float Charge
Voltage for 6-Cell Charger
TEMPERATURE (°C)
–10
V
FLOAT
(V)
10 5040 60
0 20 30
8062 F05b
12.6
12.8
13.0
13.2
13.4
13.6
13.8
14.0
14.2
14.3
–19.8mV/°C
TEMPERATURE (°C)
–10
V
FLOAT
(V)
10 5040 60
0 20 30
8062 F06b
12.8
13.0
13.2
13.4
13.6
13.8
14.0
14.6
14.4
14.2
14.8
THEORETICAL VFLOAT
PROGRAMMED VBAT(FLOAT)
8062 F06a
LTM8062
196k
69k 22k
B = 3380
69k
BAT
ADJ
198k
6-CELL
LEAD-ACID
BATTERY
+
8062 F05a
LTM8062
LINEAR
TECHNOLOGY
LM234
RFB1
210k
RFB2
43k
V+
V–
R
RSET
2.4k
BAT
ADJ
RFB3
215k
6-CELL
LEAD-ACID
BATTERY
+
Status Pins
The LTM8062/LTM8062A report charger status through
two open-collector outputs, the CHRG and FAULT pins.
These pins can be pulled up as high as VIN, and can sink
up to 10mA. The CHRG pin indicates that the charger is
delivering current at greater than a C/10 rate, or one-tenth
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of the programmed charge current. The FAULT pin signals
bad-battery and NTC faults. These pins are binary coded,
as shown in Table 3.
Table 3. Status Pin State
CHRG FAULT STATUS
High High Not Charging—Standby or Shutdown Mode
High Low Bad-Battery Fault (Precondition Timeout/EOC Failure)
Low High Normal Charging at C/10 or Greater
Low Low NTC Fault (Pause)
If the battery is removed from an LTM8062/LTM8062A
charger that is configured for C/10 termination, a low
amplitude sawtooth waveform appears at the charger
output, due to cycling between termination and recharge
events. This cycling results in pulsing at the CHRG output.
An LED connected to this pin will exhibit a blinking pat-
tern, indicating to the user that a battery is not present.
The frequency of this blinking pattern is dependent on the
output capacitance.
C/10 Charge Termination
The LTM8062/LTM8062A support a low current-based
termination scheme, where a battery charge cycle termi-
nates when the charge current falls below one-tenth the
programmed charge current, or approximately 200mA.
This termination mode is engaged by shorting the TMR pin
to ground. When C/10 termination is used, an LTM8062/
LTM8062A charger sources battery charge current as
long as the average current level remains above the C/10
threshold. As the full-charge float voltage is achieved, the
charge current falls until the C/10 threshold is reached,
at which time the charger terminates and the LTM8062/
LTM8062A enter standby mode. The CHRG status pin fol-
lows the charger cycle and is high impedance when the
charger is not actively charging. There is no provision for
bad-battery detection if C/10 termination is used.
Timer Charge Termination
The LTM8062/LTM8062A support a timer-based termina-
tion scheme, where a battery charge cycle terminates after
a specific amount of time elapses. Timer termination is
engaged when a capacitor (CTIMER) is connected from the
TMR pin to ground. The timer cycle time span (tEOC) is
determined by CTIMER in the equation:
CTIMER = tEOC • 2.27 • 10–7 (Hours)
When charging at a 1C rate, tEOC is commonly set to three
hours, which requires a 0.68μF capacitor.
The CHRG status pin continues to signal charging, regard-
less of which termination scheme is used. When timer
termination is used, the CHRG status pin is pulled low
during a charge cycle until the charge current falls below
the C/10 threshold. The charger continues to top off the
battery until timer EOC, when the LTM8062/LTM8062A
terminate the charge cycle and enters standby mode.
Termination at the end of the timer cycle only occurs if the
charge cycle was successful. A successful charge cycle
occurs when the battery is charged to within 2.5% of the
full-charge float voltage. If a charge cycle is not success-
ful at EOC, the timer cycle resets and charging continues
for another full timer cycle. When VBAT drops 2.5% from
the full-charge float voltage, whether by battery loading
or replacement of the battery, the charger automatically
resets and starts charging.
Preconditioning and Bad-Battery Fault
The LTM8062/LTM8062A have a precondition mode, where
the charge current is limited to 15% of the maximum
charge current, or approximately 300mA. Precondition
mode is engaged if the voltage on the BAT pin is below the
precondition threshold, or approximately 70% of the float
voltage. Once the BAT voltage rises above the precondition
threshold, normal full-current charging can commence. The
LTM8062/LTM8062A incorporate 90mV hysteresis to avoid
spurious mode transitions.
Bad-battery detection is engaged when the internal timer
is used for termination (capacitor tied to TMR). This fault
detection feature is designed to identify failed cells. A
bad-battery fault is triggered when the voltage on BAT
remains below the precondition threshold for greater
than one-eighth of a full timer cycle (one-eighth EOC). A
bad-battery fault is also triggered if a normally charging
battery re-enters precondition mode after one-eighth EOC.
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When a bad-battery fault is triggered, the charge cycle
is suspended, and the CHRG status pin becomes high
impedance. The FAULT pin is pulled low to signal that a
fault has been detected.
Cycling the charger’s power or shutdown function initiates
a new charge cycle, but the LTM8062/LTM8062A chargers
do not require a manual reset. Once a bad-battery fault
is detected, a new timer charge cycle initiates if the BAT
pin exceeds the precondition threshold voltage. During
a bad-battery fault, a small current is sourced from the
charger; removing the failed battery allows the charger
output voltage to rise above the preconditioning threshold
voltage and initiate a charge cycle reset. A new charge
cycle is started by connecting another battery to the
charger output.
Battery Temperature Fault: NTC
The LTM8062/LTM8062A can accommodate battery tem-
perature monitoring by using an NTC (negative tempera-
ture coefficient) thermistor close to the battery pack. The
temperature monitoring function is enabled by connecting
a 10kΩ, β ≈ 3380 NTC thermistor from the NTC pin to
ground. If the NTC function is not desired, leave the pin
open. The NTC pin sources 50μA, and monitors the voltage
dropped across the 10kΩ thermistor. When the voltage
on this pin is above 1.36V (0°C) or below 0.29V (40°C),
the battery temperature is out of range, and the LTM8062/
LTM8062A trigger an NTC fault. The NTC fault condition
remains until the voltage on the NTC pin corresponds to
a temperature within the 0°C to 40°C range. Both hot and
cold thresholds incorporate 20% hysteresis, which equates
to about 5°C. If higher operational charging temperatures
are desired, the temperature range can be expanded by
adding series resistance to the 10k NTC resistor. Adding
a 909Ω resistor will increase the effective temperature
threshold to 45°C, for example.
During an NTC fault, charging is halted and both status
pins are pulled low. If timer termination is enabled, the
timer count is suspended and held until the fault condi-
tion is cleared.
Thermal Foldback
The LTM8062/LTM8062A contains a thermal fold-
back protection feature that reduces charge current
as the IC junction temperature approaches 125°C. In
most cases, on-chip temperatures servo such that
any overtemperature conditions are relieved with
only slight reductions in maximum charge current. In
some cases, the thermal foldback protection feature
can reduce charge currents below the C/10 threshold.
In applications that use C/10 termination (TMR = 0V),
the LTM8062/LTM8062A will suspend charging and en-
ter standby mode until the overtemperature condition is
relieved.
PCB Layout
Most of the headaches associated with PCB layout have
been alleviated or even eliminated by the high level of
LTM8062/LTM8062A integration. The LTM8062/LTM8062A
is nevertheless a switching power supply, and care must be
taken to minimize EMI and ensure proper operation. Even
with the high level of integration, you may fail to achieve
specified operation with a haphazard or poor layout. See
Figure 7 for a suggested layout. Ensure that the grounding
and heat sinking are acceptable.
Figure 7. Suggested Layout and Via Placement
FAULT
ADJ
BAT
(OPTIONAL)
VIN
VINA
CHRG
GND
GND
THERMAL VIAS
TMR
NTC
RUN V
INREG
CIN
CBAT
8062 F07
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1. Place the CIN capacitor as close as possible to the VIN
and GND connection of the LTM8062/LTM8062A.
2. If used, place the CBAT capacitor as close as possible to
the BAT and GND connection of the LTM8062/LTM8062A.
3. Place the CIN and CBAT (if used) capacitors such that their
ground current flows directly adjacent or underneath
the LTM8062/LTM8062A.
4. Connect all of the GND connections to as large a copper
pour or plane area as possible on the top layer. Avoid
breaking the ground connection between the external
components and the LTM8062/LTM8062A.
5. For good heat sinking, use vias to connect the GND
copper area to the board’s internal ground planes.
Liberally distribute these GND vias to provide both a
good ground connection and thermal path to the internal
planes of the printed circuit board. Pay attention to the
location and density of the thermal vias in Figure 5. The
LTM8062/LTM8062A can benefit from the heat-sinking
afforded by vias that connect to internal GND planes at
these locations, due to their proximity to internal power
handling components. The optimum number of thermal
vias depends upon the printed circuit board design.
For example, a board might use very small via holes.
It should employ more thermal vias than a board that
uses larger holes.
Hot-Plugging Safely
The small size, robustness and low impedance of ceramic
capacitors make them an attractive option for the input
bypass capacitor of LTM8062/LTM8062A. However, these
capacitors can cause problems if the LTM8062/LTM8062A
are plugged into a live input supply (see Application Note
88 for a complete discussion). The low loss ceramic
capacitor combined with stray inductance in series with
the power source forms an underdamped tank circuit,
and the voltage at the VIN pin of the LTM8062/LTM8062A
can ring to more than twice the nominal input voltage,
possibly exceeding the LTM8062/LTM8062A’s rating and
damage the part. If the input supply is poorly controlled
or the user will be plugging the LTM8062/LTM8062A into
an energized supply, the input network should be designed
to prevent this overshoot. This can be accomplished by
installing a small resistor in series with VIN, but the most
popular method of controlling input voltage overshoot is
to add an electrolytic bulk capacitor to the VIN net. This
capacitor’s relatively high equivalent series resistance
damps the circuit and eliminates the voltage overshoot.
The extra capacitor improves low frequency ripple filter-
ing and can slightly improve the efficiency of the circuit,
though it is physically large.
Parallel Operation
If more current is desired, multiple LTM8062/LTM8062As
may be paralleled, as shown in the Typical Applications
section. When doing so, bear in mind the following:
1. Each LTM8062/LTM8062A ADJ pin requires 250k input
resistance as described in the ADJ pin function descrip-
tion. Table 1 gives the recommended resistor network
for a single LTM8062/LTM8062A. If using more than
one, either apply one network of the appropriate value
to each LTM8062/LTM8062A’s ADJ pin or apply a single
network, each resistor value divided by the number of
paralleled LTM8062/LTM8062As and connect all of the
ADJ pins together.
2. Tie the BAT outputs directly together. Apply the same
output capacitance to each LTM8062/LTM8062A as if
it were used as a single device and not paralleled.
3. The individual LTM8062/LTM8062As may not share
current equally as the battery nears the float voltage.
Thermal Considerations
The thermal performance of the LTM8062/LTM8062A is
given in the Typical Performance Characteristics section.
These curves were generated by the LTM8062/LTM8062A
mounted to a 58cm2 4-layer FR4 printed circuit board.
Boards of other sizes and layer count can exhibit differ-
ent thermal behavior, so it is incumbent upon the user to
verify proper operation over the intended system’s line,
load and environmental operating conditions.
For increased accuracy and fidelity to the actual application,
many designers use FEA to predict thermal performance.
To that end, the Pin Configuration section of the data sheet
typically gives four thermal coefficients:
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80421 F08
µMODULE DEVICE
JUNCTION-TO-CASE (TOP)
RESISTANCE
JUNCTION-TO-BOARD RESISTANCE
JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD)
CASE (TOP)-TO-AMBIENT
RESISTANCE
BOARD-TO-AMBIENT
RESISTANCE
JUNCTION-TO-CASE
(BOTTOM) RESISTANCE
JUNCTION AMBIENT
CASE (BOTTOM)-TO-BOARD
RESISTANCE
1. θJA: Thermal resistance from junction to ambient.
2. θJCbottom: Thermal resistance from junction to the bot-
tom of the product case.
3. θJCtop: Thermal resistance from junction to top of the
product case.
4. θJB: Thermal resistance from junction to the printed
circuit board.
While the meaning of each of these coefficients may seem
to be intuitive, JEDEC has defined each to avoid confusion
and inconsistency. These definitions are given in JESD
51-12, and are quoted or paraphrased below:
1. θJA is the natural convection junction-to-ambient air
thermal resistance measured in a one cubic foot sealed
enclosure. This environment is sometimes referred to as
“still air” although natural convection causes the air to
move. This value is determined with the part mounted to
a JESD 51-9 defined test board, which does not reflect
an actual application or viable operating condition.
2. θJCbottom is the junction-to-board thermal resistance
with all of the component power dissipation flowing
through the bottom of the package. In the typical
µModule device, the bulk of the heat flows out the bot-
tom of the package, but there is always heat flow out
into the ambient environment. As a result, this thermal
resistance value may be useful for comparing packages
but the test conditions don’t generally match the user’s
application.
3. θJCtop is determined with nearly all of the component
power dissipation flowing through the top of the pack-
age. As the electrical connections of the typical µModule
device are on the bottom of the package, it is rare for an
application to operate such that most of the heat flows
from the junction to the top of the part. As in the case
of θJCbottom, this value may be useful for comparing
packages but the test conditions don’t generally match
the user’s application.
4. θJB is the junction-to-board thermal resistance where
almost all of the heat flows through the bottom of the
µModule device and into the board, and is really the
sum of the θJCbottom and the thermal resistance of the
bottom of the part through the solder joints and through
a portion of the board. The board temperature is mea-
sured a specified distance from the package, using a
two sided, two layer board. This board is described in
JESD 51-9.
The most appropriate way to use the coefficients is when
running a detailed thermal analysis, such as FEA, which
considers all of the thermal resistances simultaneously.
None of them can be individually used to accurately pre-
dict the thermal performance of the product, so it would
be inappropriate to attempt to use any one coefficient to
correlate to the junction temperature versus load graphs
given in the Typical Performance Characteristics.
A graphical representation of these thermal resistances
is given in Figure 8.
Figure 8. Thermal Resistances Among µModule Device Printed Circuit Board and Ambient Environment
applicaTions inForMaTion
LTM8062/LTM8062A
19
8062fd
For more information www.linear.com/LTM8062
applicaTions inForMaTion
Typical applicaTions
8062 TA02
LTM8062
GND
VINA
VIN
VINREG
RUN
TMR
NTC
VIN
9.5V TO 32VDC BAT
BIAS
CHRG
FAULT
ADJ
4.7µF
549k
459k
2-CELL
LiFePO4
(2× 3.6V)
BATTERY
(OPTIONAL
ELECTROLYTIC
CAPACITOR)
+
Basic 2A, 2-Cell LiFePO4 Battery Charger with C/10 Termination
Basic 2A, 4-Cell Li-Ion Battery Charger with C/10 Termination
The blue resistances are contained within the µModule
device, and the green are outside.
The die temperature of the LTM8062/LTM8062A must be
lower than the maximum rating of 125°C, so care should
be taken in the layout of the circuit to ensure good heat
sinking of the LTM8062/LTM8062A. The bulk of the heat
flow out of the LTM8062/LTM8062A is through the bottom
of the module and the LGA pads into the printed circuit
board. Consequently a poor printed circuit board design
can cause excessive heating, resulting in impaired perfor-
mance or reliability. Please refer to the PCB Layout section
for printed circuit board design suggestions.
8062 TA06
LTM8062A
GND
VINA
VIN
VINREG
RUN
TMR
NTC
VIN
22V TO 32VDC BAT
CHRG
FAULT
ADJ
BIAS
4.7µF
1.24M
312k
EXTERNAL 3.3V
4-CELL
Li-Ion
(4 × 4.1V)
BATTERY
PACK
(OPTIONAL
ELECTROLYTIC
CAPACITOR)
+
LTM8062/LTM8062A
20
8062fd
For more information www.linear.com/LTM8062
2A Solar Panel Power Manager with 8.4V Lithium Ion Battery Pack and 16V Peak Power Tracking
Three LTM8062s Operating In Parallel to Produce Higher Charge Current
8062 TA03
LTM8062
GND
VINA
VIN
VINREG
RUN
TMR
NTC
VIN
SOLAR
POWER UNIT
BAT
BIAS
CHRG
FAULT
ADJ
4.7µF
642k
412k
499k 2-CELL
Li-ION
(2× 4.2V)
BATTERY
NTC
10k
B = 3380
(OPTIONAL
ELECTROLYTIC
CAPACITOR)
+
R1
549k
0.1%
C1
22µF
C4, C5, C6; MURATA, GRM32ER7YA106KA12L
C1, C2, C3; POS-CAP 16TQC22M
12V TO 32V
GND
R4
459k
0.1%
LTM8062EV
GND
VINA
VIN
VINREG
RUN
NTC
BAT
BIAS
ADJ
CHRG
FAULT
C6
10µF
35V
TMR
C3
22µF
C5
10µF
35V
+
R2
549k
0.1%
R5
459k
0.1%
C4
10µF
35V
LTM8062EV
GND
VINA
VIN
VINREG
RUN
NTC
BAT
BIAS
ADJ
CHRG
FAULT
TMR
LTM8062EV
GND
VINA
VIN
VINREG
RUN
NTC
BAT
BIAS
ADJ
CHRG
FAULT
TMR
8062 TA05
R3
549k
0.1%
R6
459k
0.1%
+
C2
22µF
BAT
7.2V, 6A
GND
+
Typical applicaTions
LTM8062/LTM8062A
21
8062fd
For more information www.linear.com/LTM8062
LGA Package
77-Lead (15mm × 9mm × 4.32mm)
(Reference LTC DWG # 05-08-1856 Rev A)
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
2. ALL DIMENSIONS ARE IN MILLIMETERS
LAND DESIGNATION PER JESD MO-222, SPP-010
5. PRIMARY DATUM -Z- IS SEATING PLANE
6. THE TOTAL NUMBER OF PADS: 77
4
3
DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL,
BUT MUST BE LOCATED WITHIN THE ZONE INDICATED.
THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE
SYMBOL
aaa
bbb
eee
TOLERANCE
0.15
0.10
0.05
4.22 – 4.42
DETAIL B
DETAIL B
SUBSTRATE
MOLD
CAP
0.27 – 0.37
3.95 – 4.05
// bbb Z
Z
15
BSC
PACKAGE TOP VIEW
9
BSC
4
PAD 1
CORNER
XY
aaa Z
aaa Z
DETAIL A
12.70
BSC
1.27
BSC
7.62
BSC
L
K
J
H
G
F
E
D
C
B
PACKAGE BOTTOM VIEW
3
PADS
SEE NOTES
A
1234567
DETAIL A
0.635 ±0.025 SQ. 76x
SYXeee
SUGGESTED PCB LAYOUT
TOP VIEW
0.000
1.270
1.270
2.540
2.540
3.810
3.810
5.080
5.080
6.350
6.350
3.810
1.270
2.540
0.000
1.270
3.810
2.540
LGA 77 0909 REV A
PAD 1
DIA (0.635)
0.9525
1.5875
0.9525
1.5875
4.1275
3.4925
PACKAGE IN TRAY LOADING ORIENTATION
LTMXXXXXX
µModule
TRAY PIN 1
BEVEL
COMPONENT
PIN “A1”
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
LTM8062/LTM8062A
22
8062fd
For more information www.linear.com/LTM8062
Table 3. Pin Assignment Table
(Arranged by Pin Number)
PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME
A1 GND B1 GND C1 GND D1 GND E1 GND F1 GND
A2 GND B2 GND C2 GND D2 GND E2 GND F2 GND
A3 GND B3 GND C3 GND D3 GND E3 GND F3 GND
A4 GND B4 GND C4 GND D4 GND E4 GND F4 GND
A5 GND B5 GND C5 GND D5 GND E5 GND F5 GND
A6 BAT B6 BAT C6 BAT D6 BAT E6 BAT F6 BAT
A7 BAT B7 BAT C7 BAT D7 BAT E7 BAT F7 BAT
PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME
G1 GND H1 GND J1 GND K1 VIN L1 VIN
G2 GND H2 GND J2 GND K2 VIN L2 VIN
G3 GND H3 GND J3 GND K3 VIN L3 VIN
G4 GND H4 GND J4 GND K4 VINA L4 VINA
G5 GND H5 GND J5 GND K5 VINA L5 VINA
G6 GND H6 NTC J6 TMR K6 RUN L6 VINREG
G7 BIAS H7 ADJ J7 FAULT K7 CHRG L7 GND
package DescripTion
package phoTos
LTM8062/LTM8062A
23
8062fd
For more information www.linear.com/LTM8062
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
A 3/11 Updated Electrical Characteristics section
Updated VINREG (Pin L6) description
Updated Block Diagram
Updated Operation section
Updated Figures 2, 7
Updated Applications Information
Updated/Added Typical Applications
3
7
8
8
9, 15
10, 11, 12, 13
18, 22
B 8/11 Added LTM8062A parts. Reflected throughout the data sheet 1-24
C 12/11 Added graph G27
Updated Typical Applications
6
19
D 7/13 Correct RW and RSET equations 13
LTM8062/LTM8062A
24
8062fd
For more information www.linear.com/LTM8062
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
LINEAR TECHNOLOGY CORPORATION 2010
LT 0713 REV D • PRINTED IN USA
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTM8062
relaTeD parTs
Typical applicaTion
2A Solar Panel Power Manager for Charging 2-Cell 8.4V Lithium-Ion Battery, Featuring Three Hour
Charge Time and 16V Peak Power Tracking. Battery Powers Two µModule Regulators
PART NUMBER DESCRIPTION COMMENTS
LTM4601/
LTM4601A
12A DC/DC µModule Regulator with PLL, Output
Tracking/Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4601-1 Version has no Remote
Sensing
LTM4618 6A DC/DC µModule Regulator 4.5V ≤ VIN ≤ 26.5V, 0.8V ≤ VOUT ≤ 5V, 9mm × 15mm × 4.32mm LGA
LTM4604A 4A Low VIN DC/DC µModule Regulator 2.375V ≤ VIN ≤ 5.5V, 0.8V ≤ VOUT ≤ 5V, 9mm × 15mm × 2.3mm LGA
LTM4608A 8A Low VIN DC/DC µModule Regulator 2.7V ≤ VIN ≤ 5.5V, 0.6V ≤ VOUT ≤ 5V, 9mm × 15mm × 2.8mm LGA
LTM8020 200mA, 36V DC/DC µModule Regulator EN55022 Class B Compliant, Fixed 450kHz Frequency, 1.25V ≤ VOUT ≤ 5V,
6.25mm × 6.25mm × 2.32mm LGA
LTM8022 1A, 36V DC/DC µModule Regulator Adjustable Frequency, 0.8V ≤ VOUT ≤ 10V, 9mm × 11.25mm × 2.82mm LGA,
Pin Compatible to the LTM8023
LTM8023 2A, 36V DC/DC µModule Regulator Adjustable Frequency, 0.8V ≤ VOUT ≤ 10V, 9mm × 11.25mm × 2.82mm LGA,
Pin Compatible to the LTM8022
LTM8025 3A, 36V DC/DC µModule Regulator 0.8V ≤ VOUT ≤ 24V, 9mm × 15mm × 4.32mm LGA
LTM8021 500mA, 36V DC/DC µModule Regulator EN55022 Class B Compliant, Fixed 1.1MHz Frequency, 0.8V ≤ VOUT ≤ 5V,
6.25mm × 11.25mm × 2.82mm LGA
LTM8042/
LTM8042-1
1A/350mA µModule LED Driver 3V ≤ VIN ≤ 30V, VLED Up to 28V, Buck, Boost or Buck-Boost Operation
9mm × 15mm × 2.82mm LGA
8062 TA04
LTM8062 LTM8023
GND
VINA
VIN
VINREG
RUN
TMR
NTC
VIN
SOLAR
POWER UNIT
BAT
BIAS
CHRG
FAULT
ADJ
4.7µF
642k
412k
499k
0.68µF
LTM8021
2-CELL
Li-Ion
(2× 4.2V)
BATTERY
NTC
10k
B = 3380
VOUT
VOUT