1
LT1610
1.7MHz, Single Cell
Micropower
DC/DC Converter
■
Uses Tiny Capacitors and Inductor
■
Internally Compensated
■
Low Quiescent Current: 30
µ
A
■
Operates with V
IN
as Low as 1V
■
3V at 30mA from a Single Cell
■
5V at 200mA from 3.3V
■
High Output Voltage Capability: Up to 28V
■
Low Shutdown Current: <1µA
■
Automatic Burst Mode
TM
Switching at Light Load
■
Low V
CESAT
Switch: 300mV at 300mA
■
8-Lead MSOP and SO Packages
The LT
®
1610 is a micropower fixed frequency DC/DC
converter that operates from an input voltage as low as 1V.
Intended for small, low power applications, it switches at
1.7MHz, allowing the use of tiny capacitors and inductors.
The device can generate 3V at 30mA from a single cell
(1V) supply. An internal compensation network can be
connected to the LT1610’s VC pin, eliminating two exter-
nal components. No-load quiescent current of the LT1610
is 30µA, and the internal NPN power switch handles a
300mA current with a voltage drop of 300mV.
The LT1610 is available in 8-lead MSOP and SO packages.
Burst Mode is a trademark of Linear Technology Corporation.
Figure 1. 1-Cell to 3V Step-Up Converter
Efficiency
■
Pagers
■
Cordless Phones
■
Battery Backup
■
LCD Bias
■
Portable Electronic Equipment
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
C2
22µF
C1
22µF
1 CELL
L1
4.7µHD1 V
OUT
3V
30mA
C1, C2: AVX TAJA226M006R
D1: MOTOROLA MBR0520
L1: MURATA LQH1C4R7
1610 F01
+
+
R1
1M
R2
681k
65
2
7
4
1
8
3
V
IN
SW
PGND
FB
SHDN
GNDCOMP
LT1610
V
C
LOAD CURRENT (mA)
0.1
EFFICIENCY (%)
85
80
75
70
65
60
55
50 1 10 100
1610 TA01
V
OUT
= 3V
V
IN
= 1.5V
V
IN
= 1V
V
IN
= 1.25V
2
LT1610
ABSOLUTE MAXIMUM RATINGS
W
WW
U
PACKAGE/ORDER INFORMATION
W
UU
T
JMAX
= 125°C, θ
JA
= 160°C/W
T
JMAX
= 125°C, θ
JA
= 120°C/W
(Note 1)
V
IN
Voltage ................................................................ 8V
SW Voltage ............................................... –0.4V to 30V
FB Voltage ..................................................... V
IN
+ 0.3V
V
C
Voltage ................................................................ 2V
COMP Voltage .......................................................... 2V
Current into FB Pin .............................................. ±1mA
SHDN Voltage ............................................................ 8V
Consult factory for Military grade parts.
Maximum Junction Temperature ......................... 125°C
Operating Temperature Range (Note 1)
Commercial ............................................. 0°C to 70°C
Extended Commercial (Note 2).......... –40°C to 85°C
Industrial ........................................... –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
ORDER PART
NUMBER
LT1610CS8
LT1610IS8
S8 PART MARKING
1610
1610I
ORDER PART
NUMBER
LT1610CMS8
MS8 PART MARKING
LTDT
1
2
3
4
V
C
FB
SHDN
PGND
8
7
6
5
COMP
GND
V
IN
SW
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
1
2
3
4
8
7
6
5
TOP VIEW
V
C
FB
SHDN
PGND
COMP
GND
V
IN
SW
S8 PACKAGE
8-LEAD PLASTIC SO
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage 0.9 1 V
Maximum Operating Voltage 8V
Feedback Voltage ●1.20 1.23 1.26 V
Quiescent Current V
SHDN
= 1.5V, Not Switching 30 60 µA
Quiescent Current in Shutdown V
SHDN
= 0V, V
IN
= 2V 0.01 0.5 µA
V
SHDN
= 0V, V
IN
= 5V 0.01 1.0 µA
FB Pin Bias Current ●27 80 nA
Reference Line Regulation 1V ≤ V
IN
≤ 2V (25°C, 0°C) 0.6 1 %/V
1V ≤ V
IN
≤ 2V (70°C) 2 %/V
2V ≤ V
IN
≤ 8V (25°C, 0°C) 0.03 0.15 %/V
2V ≤ V
IN
≤ 8V (70°C) 0.2 %/V
Error Amp Transconductance ∆I = 2µA25µmhos
Error Amp Voltage Gain 100 V/V
Switching Frequency ●1.4 1.7 2 MHz
Maximum Duty Cycle 77 80 95 %
●75 95 %
ELECTRICAL C CHARA TERISTICS
The ● denotes specifications which apply over the specified temperature
range, otherwise specifications are at TA = 25°C. Commercial grade 0°C to 70°C, VIN = 1.5V, VSHDN = VIN, unless otherwise noted.
(Note 2)
3
LT1610
ELECTRICAL C CHARA TERISTICS
The ● denotes specifications which apply over the specified temperature
range, otherwise specifications are at TA = 25°C. Commercial grade 0°C to 70°C, VIN = 1.5V, VSHDN = VIN, unless otherwise noted.
(Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch Current Limit (Note 3) 450 600 900 mA
Switch V
CESAT
I
SW
= 300mA 300 350 mV
●400 mV
Switch Leakage Current V
SW
= 5V 0.01 1 µA
SHDN Input Voltage High 1V
SHDN Input Voltage Low 0.3 V
SHDN Pin Bias Current V
SHDN
= 3V 10 µA
V
SHDN
= 0V 0.01 0.1 µA
The ● denotes specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C.
Industrial grade –40°C to 85°C, VIN = 1.5V, VSHDN = VIN, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage T
A
= 85°C 0.9 1 V
T
A
= –40°C 1.25 V
Maximum Operating Voltage 8V
Feedback Voltage ●1.20 1.23 1.26 V
Quiescent Current 30 60 µA
Quiescent Current in Shutdown V
SHDN
= 0V, V
IN
= 2V 0.01 0.5 µA
V
SHDN
= 0V, V
IN
= 5V 0.01 1.0 µA
FB Pin Bias Current ●27 80 nA
Reference Line Regulation 2V ≤ V
IN
≤ 8V (–40°C) 0.03 0.15 %/V
2V ≤ V
IN
≤ 8V (85°C) 0.2 %/V
Error Amp Transconductance ∆I = 2µA25µmhos
Error Amp Voltage Gain 100 V/V
Switching Frequency (Note 4) ●1.4 1.7 2 MHz
Maximum Duty Cycle (Note 4) 77 80 95 %
●75 95 %
Switch Current Limit 450 600 900 mA
Switch V
CESAT
I
SW
= 300mA 300 350 mV
●400 mV
Switch Leakage Current V
SW
= 5V 0.01 1 µA
SHDN Input Voltage High 1V
SHDN Input Voltage Low 0.3 V
SHDN Pin Bias Current V
SHDN
= 3V 10 µA
V
SHDN
= 0V 0.01 0.1 µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT1610C is guaranteed to meet specified performance from
0°C to 70°C and is designed, characterized and expected to meet these
extended temperature limits, but is not tested at –40°C and 85°C. The
LT1610I is guaranteed to meet the extended temperature limits.
Note 3: Current limit guaranteed by design and/or correlation to static test.
Current limit is affected by duty cycle due to ramp generator. See Block
Diagram.
Note 4: Not 100% tested at 85°C.
4
LT1610
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Current Limit vs Duty CycleV
CESAT
vs Current
SWITCH CURRENT (mA)
0
100
VCESAT (mV)
200
300
400
500
600
100 200 300 400
1610 G01
500 600
TA = 85°C
TA = –40°C
TA = 25°C
Current Limit (DC = 30%)
vs Temperature
TEMPERATURE (°C)
–50
200
SWITCH CURRENT LIMIT (mA)
300
400
500
600
800
–25 02550
1610 G02
75 100
700
Oscillator Frequency
vs Input Voltage Feedback Voltage
SHDN Pin Current
vs SHDN Pin Voltage
Transient Response,
Circuit of Figure 1
SHDN VOLTAGE (V)
0
SHDN CURRENT (µA)
30
40
50
35 8
1610 G07
20
10
012 467
V
OUT
50mV/DIV
AC COUPLED
I
L1
100mA/DIV
31mA
1mA
I
LOAD
V
IN
= 1.25V 500µs/DIV
V
OUT
= 3V
1610 TA08
DUTY CYCLE (%)
0
CURRENT LIMIT (mA)
800
700
600
500
400
300
200
100
080
1610 G03
20 40 60 1007010 30 50 90
T
A
= 25°C
INPUT VOLTAGE (V)
0
0
SWITCHING FREQUENCY (MHz)
0.25
0.75
1.00
1.25
2.50
1.75
245
1610 G04
0.50
2.00
2.25
1.50
13 678
T
A
= 25°C
TEMPERATURE (°C)
–50
1.210
FEEDBACK VOLTAGE (V)
1.215
1.220
1.225
1.230
1.240
–25 02550
1610 G05
75 100
1.235
Quiescent Current
vs Temperature
TEMPERATURE (°C)
–50
QUIESCENT CURRENT (µA)
15
20
25
25 75
1610 G06
10
5
0–25 0 50
30
35
40
100
Burst Mode Operation,
Circuit of Figure 1
V
OUT
20mV/DIV
AC COUPLED
SWITCH
VOLTAGE
2V/DIV
V
IN
= 1.25V 20µs/DIV
V
OUT
= 3V
I
LOAD
= 3mA
1610 TA08
SWITCH
CURRENT
50mA/DIV
5
LT1610
PIN FUNCTIONS
UUU
V
C
(Pin 1): Error Amplifier Output. Frequency compensa-
tion network must be connected to this pin, either internal
(COMP pin) or external series RC to ground. 220kΩ/
220pF typical value.
FB (Pin 2): Feedback Pin. Reference voltage is 1.23V.
Connect resistive divider tap here. Minimize trace area at
FB. Set V
OUT
according to V
OUT
= 1.23V (1 + R1/R2).
SHDN (Pin 3): Shutdown. Ground this pin to turn off
device. Tie to 1V or more to enable.
PGND (Pin 4): Power Ground. Tie directly to local ground
plane.
SW (Pin 5): Switch Pin. Connect inductor/diode here.
Minimize trace area at this pin to keep EMI down.
V
IN
(Pin 6): Input Supply Pin. Must be locally bypassed.
GND (Pin 7): Signal Ground. Carries all device ground
current except switch current. Tie to local ground plane.
COMP (Pin 8): Internal Compensation Network. Tie to V
C
pin, or let float if external compensation is used. Output
capacitor must be tantalum if COMP pin is used for com-
pensation.
BLOCK DIAGRA
W
FB
FB
BIAS
V
C
R5
40k
1.7MHz
OSCILLATOR
RAMP
GENERATOR
FF
S
RQ
0.15Ω
V
IN
V
IN
–
+
–
+
COMP
4
7
3
8
5
6
1
–
+
A = 3
V
OUT
SW
GND
Q1 Q2
× 10
Q3
PGND
A2
1610 F02
SHDNSHUTDOWN
ENABLE
COMPARATOR
DRIVER
R6
40k
R3
30k
R2
(EXTERNAL)
R
C
C
C
R4
140k
R1
(EXTERNAL)
–
+
A1
g
m
2
Σ
Figure 2. LT1610 Block Diagram
6
LT1610
APPLICATIONS INFORMATION
WUUU
OPERATION
The LT1610 combines a current mode, fixed frequency
PWM architecture with Burst Mode micropower operation
to maintain high efficiency at light loads. Operation can be
best understood by referring to the block diagram in
Figure 2. Q1 and Q2 form a bandgap reference core whose
loop is closed around the output of the converter. When
V
IN
is 1V, the feedback voltage of 1.23V, along with an
70mV drop across R5 and R6, forward biases Q1 and Q2’s
base collector junctions to 300mV. Because this is not
enough to saturate either transistor, FB can be at a higher
voltage than V
IN
. When there is no load, FB rises slightly
above 1.23V, causing V
C
(the error amplifier’s output) to
decrease. When V
C
reaches the bias voltage on hysteretic
comparator A1, A1’s output goes low, turning off all
circuitry except the input stage, error amplifier and low-
battery detector. Total current consumption in this state is
30µA. As output loading causes the FB voltage to de-
crease, A1’s output goes high, enabling the rest of the IC.
Switch current is limited to approximately 100mA initially
after A1’s output goes high. If the load is light, the output
voltage (and FB voltage) will increase until A1’s output
goes low, turning off the rest of the LT1610. Low fre-
quency ripple voltage appears at the output. The ripple
frequency is dependent on load current and output capaci-
tance. This Burst Mode operation keeps the output regu-
lated and reduces average current into the IC, resulting in
high efficiency even at load currents of 1mA or less.
If the output load increases sufficiently, A1’s output remains
high, resulting in continuous operation. When the LT1610
is running continuously, peak switch current is controlled
by V
C
to regulate the output voltage. The switch is turned
on at the beginning of each switch cycle. When the sum-
mation of a signal representing switch current and a ramp
generator (introduced to avoid subharmonic oscillations at
duty factors greater than 50%) exceeds the V
C
signal,
comparator A2 changes state, resetting the flip-flop and
turning off the switch. Output voltage increases as switch
current is increased. The output, attenuated by a resistor
divider, appears at the FB pin, closing the overall loop.
Frequency compensation is provided by either an external
series RC network connected between the V
C
pin and
ground or the internal RC network on the COMP pin (Pin
8). The typical values for the internal RC are 50k and 50pF.
LAYOUT
Although the LT1610 is a relatively low current device, its
high switching speed mandates careful attention to layout
for optimum performance. For boost converters, follow
the component placement indicated in Figure 3 for the best
results. C2’s negative terminal should be placed close to
Pin 4 of the LT1610. Doing this reduces switching currents
in the ground copper which keeps high frequency “spike”
noise to a minimum. Tie the local ground into the system
ground plane at one point only, using a few vias, to avoid
introducing dI/dt induced noise into the ground plane.
1
2
8
7
3
4
6
5
L1
C2
LT1610
V
OUT
V
IN
GND
SHUTDOWN
R1
R2
MULTIPLE
VIAs
GROUND PLANE
1610 F03
+
C1
D1
+
Figure 3. Recommended Component Placement for Boost Converter. Note Direct High Current Paths Using
Wide PC Traces. Minimize Trace Area at Pin 1 (VC) and Pin 2 (FB). Use Multiple Vias to Tie Pin 4 Copper to
Ground Plane. Use Vias at One Location Only to Avoid Introducing Switching Currents into the Ground Plane
7
LT1610
APPLICATIONS INFORMATION
WUUU
A SEPIC (Single-Ended Primary Inductance Converter)
schematic is shown in Figure 4. This converter topology
produces a regulated output over an input voltage range
1
2
8
7
3
4
6
5
C2
LT1610
V
IN
GND
SHUTDOWN
R1
R2
MULTIPLE
VIAs
GROUND PLANE
1610 F05
+
C3
D1
V
OUT
L1 L2
C1
+
Figure 5. Recommended Component Placement for SEPIC
SHUTDOWN
C2
22µF
6.3V
C1
22µF
6.3V
L1
22µH
L2
22µH
C3
1µF
CERAMIC D1
INPUT
Li-ION
3V to 4.2V
V
OUT
3.3V
120mA
1610 F04
+
+
1M
604k
C1, C2: AVX TAJA226M006
C3: AVX 1206YC105 (X7R)
D1: MOTOROLA MBR0520
L1, L2: MURATA LQH3C220 (UNCOUPLED)
OR SUMIDA CLS62-220 (COUPLED)
65
•
•
2
3
4
7
8
1
V
IN
SW
PGND
FB
SHDN
GND
COMP
LT1610
V
C
Figure 4. Li-Ion to 3.3V SEPIC DC/DC Converter
that spans (i.e., can be higher or lower than) the output.
Recommended component placement for a SEPIC is
shown in Figure 5.
8
LT1610
APPLICATIONS INFORMATION
WUUU
COMPONENT SELECTION
Inductors
Inductors used with the LT1610 should have a saturation
current rating (–30% of zero current inductance) of ap-
proximately 0.5A or greater. DCR should be 0.5Ω or less.
The value of the inductor should be matched to the power
requirements and operating voltages of the application. In
most cases a value of 4.7µH or 10µH is suitable. The Murata
LQH3C inductors specified throughout the data sheet are
small and inexpensive, and are a good fit for the LT1610.
Alternatives are the CD43 series from Sumida and the
DO1608 series from Coilcraft. These inductors are slightly
larger but will result in slightly higher circuit efficiency.
Chip inductors, although tempting to use because of their
small size and low cost, generally do not have enough
energy storage capacity or low enough DCR to be used
successfully with the LT1610.
Diodes
The Motorola MBR0520 is a 0.5 amp, 20V Schottky diode.
This is a good choice for nearly any LT1610 application,
unless the output voltage or the circuit topology require a
diode rated for higher reverse voltages. Motorola also
offers the MBR0530 (30V) and MBR0540 (40V) versions.
Most one-half amp and one amp Schottky diodes are
suitable; these are available from many manufacturers. If
you use a silicon diode, it must be an ultrafast recovery
type. Efficiency will be lower due to the silicon diode’s
higher forward voltage drop.
Capacitors
The input capacitor must be placed physically close to the
LT1610. ESR is not critical for the input. In most cases
inexpensive tantalum can be used.
The choice of output capacitor is far more important. The
quality of this capacitor is the greatest determinant of the
output voltage ripple. The output capacitor performs two
major functions. It must have enough capacitance to
satisfy the load under transient conditions and it must
shunt the AC component of the current coming through
the diode from the inductor. The ripple on the output
results when this AC current passes through the finite
impedance of the output capacitor. The capacitor should
have low impedance at the 1.7MHz switching frequency of
the LT1610. At this frequency, the impedance is usually
dominated by the capacitor’s equivalent series resistance
(ESR). Choosing a capacitor with lower ESR will result in
lower output ripple.
Perhaps the best way to decrease ripple is to add a 1µF
ceramic capacitor in parallel with the bulk output capaci-
tor. Ceramic capacitors have very low ESR and 1µF is
enough capacitance to result in low impedance at the
switching frequency. The low impedance can have a
dramatic effect on output ripple voltage. To illustrate,
examine Figure 6’s circuit, a 4-cell to 5V/100mA SEPIC
DC/DC converter. This design uses inexpensive aluminum
electrolytic capacitors at input and output to keep cost
down. Figure 7 details converter operation at a 100mA
load, without ceramic capacitor C5. Note the 400mV
spikes on V
OUT
.
After C5 is installed, output ripple decreases by a factor of
8 to about 50mV
P-P
. The addition of C5 also improves
efficiency by 1 to 2 percent.
Low ESR and the required bulk output capacitance can be
obtained using a single larger output capacitor. Larger
tantalum capacitors, newer capacitor technologies (for
example the POSCAP from Sanyo and SPCAP from
Panasonic) or large value ceramic capacitors will reduce
the output ripple. Note, however, that the stability of the
circuit depends on both the value of the output capacitor
and its ESR. When using low value capacitors or capaci-
tors with very low ESR, circuit stability should be evalu-
ated carefully, as described below.
Loop Compensation
The LT1610 is a current mode PWM switching regulator
that achieves regulation with a linear control loop. The
LT1610 provides the designer with two methods of com-
pensating this loop. First, you can use an internal compen-
sation network by tying the COMP pin to the V
C
pin. This
results in a very small solution and reduces the circuit’s
total part count. The second option is to tie a resistor R
C
and a capacitor C
C
in series from the V
C
pin to ground. This
allows optimization of the transient response for a wide
variety of operating conditions and power components.
9
LT1610
APPLICATIONS INFORMATION
WUUU
V
OUT
200mV/DIV
I
DIODE
500mA/DIV
SWITCH
VOLTAGE
10V/DIV
100ns/DIV 1610 F07
Figure 7. Switching Waveforms Without Ceramic Capacitor C5
V
OUT
50mV/DIV
I
DIODE
500mA/DIV
SWITCH
VOLTAGE
10V/DIV
V
IN
= 4.1V 100ns/DIV 1610 F08
LOAD = 100mA
Figure 8. Switching Waveforms with Ceramic Capacitor C5.
Note the 50mV/DIV Scale for VOUT
Figure 6. 4-Cell Alkaline to 5V/120mA SEPIC DC/DC Converter
It is best to choose the compensation components empiri-
cally. Once the power components have been chosen
(based on size, efficiency, cost and space requirements),
a working circuit is built using conservative (or merely
guessed) values of R
C
and C
C
. Then the response of the
circuit is observed under a transient load, and the compen-
sation network is modified to achieve stable operation.
Linear Technology’s Application Note 19 contains a de-
tailed description of the method. A good starting point for
the LT1610 is C
C
~ 220pF and R
C
~ 220k.
All Ceramic, Low Profile Design
Large value ceramic capacitors that are suitable for use as
the main output capacitor of an LT1610 regulator are now
available. These capacitors have very low ESR and there-
fore offer very low output ripple in a small package.
However, you should approach their use with some
caution.
Ceramic capacitors are manufactured using a number of
dielectrics, each with different behavior across tempera-
ture and applied voltage. Y5V is a common dielectric used
for high value capacitors, but it can lose more than 80% of
the original capacitance with applied voltage and extreme
temperatures. The transient behavior and loop stability of
the switching regulator depend on the value of the output
capacitor, so you may not be able to afford this loss. Other
dielectrics (X7R and X5R) result in more stable character-
istics and are suitable for use as the output capacitor. The
X7R type has better stability across temperature, whereas
the X5R is less expensive and is available in higher values.
The second concern in using ceramic capacitors is that
many switching regulators benefit from the ESR of the
SHUTDOWN
C2
22µF
6.3V
C1
22µF
6.3V
L1
22µH
L2
22µH
C3
1µF
CERAMIC D1 VOUT
5V
120mA
1610 F06
+
+C4
1µF
CERAMIC
1M
324k
C1, C2: ALUMINUM ELECTROLYTIC
C3 TO C5: CERAMIC X7R OR X5R
D1: MBR0520
L1, L2: MURATA LQH3C220 OR SUMIDA CLS62-220
C5
1µF
CERAMIC
65
•
•
2
3
4
7
8
1
VIN SW
PGND
FB
SHDN
GND
COMP
LT1610
VC
4 CELLS
10
LT1610
APPLICATIONS INFORMATION
WUUU
output capacitor because it introduces a zero in the
regulator’s loop gain. This zero may not be effective
because the ceramic capacitor’s ESR is very low. Most
current mode switching regulators (including the LT1610)
can easily be compensated without this zero. Any design
should be tested for stability at the extremes of operating
temperatures; this is particularly so of circuits that use
ceramic output capacitors.
Figure 9 details a 2.5V to 5V boost converter. Transient
response to a 5mA to 105mA load step is pictured in Figure
10. The “double trace” of V
OUT
at 105mA load is due to the
ESR of C2. This ESR aids stability. In Figure 11, C2 is
replaced by a 10µF ceramic capacitor. Note the low phase
margin; at higher input voltage, the converter may oscil-
late. After replacing the internal compensation network
with an external 220pF/220k series RC, the transient
response is shown in Figure 12. This is acceptable tran-
sient response.
Table 1
FIGURE C2 COMPENSATION
10 AVX TAJA226M006 Tantalum Internal
11 Taiyo Yuden JMK316BJ106 Internal
12 Taiyo Yuden JMK316BJ106 220pF/220k
C2
22µF
R2
324k
C1
22µF
L1
10µHD1 VOUT
5V
100mA
VIN
2.5V
1610 F09
+
+
1M
RC
CC
C1: AVX TAJA226M006
C2: SEE TABLE
D1: MOTOROLA MBR0520
L1: MURATA LQH30100
65
2
7
4
8
1
3
VIN SW
PGND
FB
SHDN
GNDVC
LT1610
COMP
Figure 9. 2.5V to 5V Boost Converter Can Operate with a
Ceramic Output Capacitor as Long as Proper RC and CC
are Used. Disconnect COMP Pin if External Compensation
Components Are Used
V
OUT
100mV/DIV
105mA
5mA
LOAD
CURRENT
500µs/DIV 1610 F10
Figure 10. Tantalum Output Capacitor
and Internal RC Compensation
V
OUT
100mV/DIV
105mA
5mA
LOAD
CURRENT
500µs/DIV 1610 F11
Figure 11. 10µF X5R-Type Ceramic Output Capacitor
and Internal RC Compensation has Low Phase Margin
V
OUT
100mV/DIV
105mA
5mA
LOAD
CURRENT
500µs/DIV 1610 F12
Figure 12. Ceramic Output Capacitor with 220pF/220k
External Compensation has Adequate Phase Margin
11
LT1610
TYPICAL APPLICATIONS
U
C2
15µF
C1
15µF
2 CELLS
L1
4.7µHD1 V
OUT
5V
50mA
1610 TA02
+
+
1M
324k
C1, C2: AVX TAJA156M010R
D1: MOTOROLA MBR0520
L1: SUMIDA CD43-4R7
MURATA LQH1C4R7
65
2
7
4
1
8
3
V
IN
SW
PGND
FB
SHDN
GNDCOMP
LT1610
V
C
LOAD CURRENT (mA)
0.1
EFFICIENCY (%)
90
80
70
60
50 110
1610 TA03
100 1000
VIN = 1.5V
VIN = 3V
VIN = 2V
Efficiency2-Cell to 5V Converter
C2
33µF
C1
10µF
2 CELLS
L1
4.7µHD1 V
OUT
3.3V
70mA
1610 TA04
+
+
R2
1M
R3
604k
C1: AVX TAJA106M010R
C2: AVX TAJB336M006R
D1: MBR0520
L1: MURATA LQH3C4R7
65
2
3
4
7
8
1V
IN
SW
PGND
FB
V
C
SHDNCOMP
LT1610
SHUTDOWN
GND
LOAD (mA)
60
EFFICIENCY (%)
70
80
90
0.1 10 100 1000
1610 TA05
50 1
3.3VOUT
3VIN
1.5VIN
2VIN
Efficiency2-Cell to 3.3V Converter
Efficiency
5V to 12V/100mA Boost Converter
LOAD CURRENT (mA)
0.1
70
EFFICIENCY (%)
80
90
1 10 100
1610 TA07
60
65
75
85
55
50
C2
15µF
L1
10µH
V
IN
5V
D1 V
OUT
12V
100mA
1610 TA06
+
C1
15µF
+
R2
1M
R3
115k
C1: AVX TAJA156M010
C2: AVX TAJB156M016
D1: MOTOROLA MBR0520
L1: MURATA LQH3C100M24
65
2
3
4
7
8
1V
IN
SW
PGND
FB
V
C
SHDNCOMP
LT1610
SHUTDOWN
GND
12
LT1610
TYPICAL APPLICATIONS
U
C2
15µF
L1
10µH
V
IN
5V
D1 V
OUT
9V
150mA
1610 TA08
+
C1
15µF
+
R2
1M
R3
158k
C1: AVX TAJA156M010
C2: AVX TAJB156M016
D1: MOTOROLA MBR0520
L1: MURATA LQH3C100M24
65
2
3
4
7
8
1V
IN
SW
PGND
FB
V
C
SHDNCOMP
LT1610
SHUTDOWN
GND
5V to 9V/150mA Boost Converter Efficiency
LOAD CURRENT (mA)
1
70
EFFICIENCY (%)
80
90
10 100 300
1610 TA09
60
65
75
85
55
50
V
OUT
200mV/DIV
140mA
10mA
LOAD
CURRENT
INDUCTOR
CURRENT
200mA/DIV
200µs/DIV 1610 TA10
5V to 9V Boost Converter Transient Response
13
LT1610
TYPICAL APPLICATIONS
U
3.3V TO 8V/70mA, –8V/5mA, 24V/5mA TFT LCD Bias Supply Uses All Ceramic Capacitors
D1
D4
0.22µF
L1
5.4µH
65
8
2
4
7
3
1
V
IN
SW
LT1610
PGND
COMP
V
C
FB
SHDN
GND
0.22µF
100k
48.7k
1610 TA18
274k
C1
4.7µF
V
IN
3.3V
C2
4.7µF
1µF
1µF
1µF
0.22µF
AV
DD
8V
70mA
0.22µF: TAIYO YUDEN EMK212BJ224MG
1µF: TAIYO YUDEN LMK212BJ105MG
4.7µF: TAIYO YUDEN LMK316BJ475ML
D1: MOTOROLA MBRO520
D2, D3, D4: BAT54S
L1: SUMIDA CDRH5D185R4
V
ON
24V
5mA
V
OFF
–8V
5mA
51pF
D3
D2
TFT LCD Bias Supply Transient Response
AV
DD
200mV/DIV
V
ON
500mV/DIV
V
OFF
200mV/DIV
70mA
25mA
AV
DD
LOAD
200µs/DIV 1610 TA19
V
ON
LOAD = 5mA
V
OFF
LOAD = 5mA
14
LT1610
TYPICAL APPLICATIONS
U
C
BIG
C1
15µF
15k
1 AA
ALKALINE
CHARGE
SHUTDOWN
L1
4.7µHD1
Q1
V
OUT
4.5V
C1, C2: AVX TAJA156M010
D1: MOTOROLA MBR0530T1
L1: MURATA LQH1C4R7
Q1: 2N3906
1610 TA11
+
C2
15µF
+
+
R1
200k
R4
20Ω
R3
845k
R2
2M
65
8
2
4
3.3nF
7
1
3V
IN
SW
PGND
COMP
SHDN
FBV
C
LT1610
GND
Single Cell Super Cap Charger
OUTPUT VOLTAGE (V)
2.0
0
OUTPUT CURRENT (mA)
5
10
15
20
25
2.5 3.0 3.5 4.0
1610 TA12
4.5 5.0
OUTPUT VOLTAGE (V)
2.0
0
OUTPUT POWER (mW)
10
20
30
40
60
2.5 3.0 3.5 4.0
1610 TA13
4.5 5.0
50
Super Cap Charger Output Current vs Output Voltage Super Cap Charger Output Power vs Output Voltage
15
LT1610
PACKAGE DESCRIPTION
U
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
MSOP (MS8) 1197
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
0.021 ± 0.006
(0.53 ± 0.015)
0° – 6° TYP
SEATING
PLANE
0.007
(0.18)
0.040 ± 0.006
(1.02 ± 0.15)
0.012
(0.30)
REF
0.006 ± 0.004
(0.15 ± 0.102)
0.034 ± 0.004
(0.86 ± 0.102)
0.0256
(0.65)
TYP
12
34
0.192 ± 0.004
(4.88 ± 0.10)
8765
0.118 ± 0.004*
(3.00 ± 0.102)
0.118 ± 0.004**
(3.00 ± 0.102)
1234
0.150 – 0.157**
(3.810 – 3.988)
8765
0.189 – 0.197*
(4.801 – 5.004)
0.228 – 0.244
(5.791 – 6.197)
0.016 – 0.050
(0.406 – 1.270)
0.010 – 0.020
(0.254 – 0.508)× 45°
0°– 8° TYP
0.008 – 0.010
(0.203 – 0.254)
SO8 0996
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
TYP
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
*
**
16
LT1610
1610f LT/TP 0699 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1998
TYPICAL APPLICATIONS N
U
Li-Ion to 3.3V SEPIC DC/DC Converter
PART NUMBER DESCRIPTION COMMENTS
LTC®1474 Micropower Step-Down DC/DC Converter 94% Efficiency, 10µA I
Q
, 9V to 5V at 250mA
LT1307 Single Cell Micropower 600kHz PWM DC/DC Converter 3.3V at 75mA from 1 Cell, MSOP Package
LTC1440/1/2 Ultralow Power Single/Dual Comparators with Reference 2.8µA I
Q
, Adjustable Hysteresis
LTC1502-3.3 Single Cell to 3.3V Regulated Charge Pump 40µA I
Q
, No Inductors, 3.3V at 10mA from 1V Input
LT1521 Micropower Low Dropout Linear Regulator 500mV Dropout, 300mA Current, 12µA I
Q
LT1611 Inverting 1.4MHz DC/DC Converter 5V to –5V at 150mA, Tiny SOT-23 Package
LT1613 Step-Up 1.4MHz DC/DC Converter 3.3V to 5V at 200mA, Tiny SOT-23 Package
LTC1682 Doubler Charge Pump with Low Noise Linear Regulator Fixed 3.3V and 5V Outputs, 1.8V to 4.4V Input Range, 50mA Output
RELATED PARTS
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear-tech.com
SHUTDOWN
C2
22µF
6.3V
C1
22µF
6.3V
L1
22µH
L2
22µH
C3
1µF
CERAMIC D1
INPUT
Li-ION
3V to 4.2V
V
OUT
3.3V
120mA
1610 TA14
+
+
1M
604k
C1, C2: AVX TAJB226M006
C3: AVX 1206YC105 (X7R)
D1: MOTOROLA MBR0520
L1, L2: MURATA LQH3C220 (UNCOUPLED)
OR SUMIDA CLS62-220 (COUPLED)
65
•
•
2
3
4
7
8
1
V
IN
SW
PGND
FB
SHDN
GND
COMP
LT1610
V
C
Efficiency
LOAD CURRENT (mA)
0.1
EFFICIENCY (%)
60
70
80
1 10 100
1610 TA15
50
40
30
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
SHUTDOWN
C2
22µF
6.3V
C1
22µF
6.3V
L1
22µH
L2
22µH
C3
1µF
CERAMIC D1 V
OUT
5V
120mA
1610 TA16
+
+
1M
324k
C1, C2: AVX TAJB226M006
C3: AVX 1206YC105 (X7R)
D1: MOTOROLA MBR0520
L1, L2: MURATA LQH3C220 (UNCOUPLED)
OR SUMIDA CLS62-220 (COUPLED)
65
•
•
2
3
4
7
8
1
V
IN
SW
PGND
FB
SHDN
GND
COMP
LT1610
V
C
4 CELLS
4-Cell to 5V/120mA SEPIC DC/DC Converter
LOAD CURRENT (mA)
0.1
EFFICIENCY (%)
60
70
80
1 10 100
1610 TA17
50
40
30
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 5V
V
IN
= 6.5V
4-Cell to 5V Efficiency