LTC4010 - Linear Technology

LTC4010

4010p

High Efficiency Standalone

Nickel Battery Charger

■

Complete NiMH/NiCd Charger for 1 to 16 Cells

■

No Microcontroller or Firmware Required

■

550kHz PWM Current Source Controller

■

No Audible Noise with Ceramic Capacitors

■

Wide Input Voltage Range: 5.5V to 34V

■

Programmable Charge Current: 5% Accuracy

■

Automatic Trickle Precharge

■

–∆V Fast Charge Termination

■

Optional ∆T/∆t Fast Charge Termination

■

Optional Temperature Qualification

■

Automatic NiMH Top-Off Charge

■

Programmable Maximum Charging Durations

■

Automatic Recharge

■

Multiple Status Outputs

■

Micropower Shutdown

■

16-Lead Thermally Enhanced TSSOP Package

■

Integrated or Standalone Battery Charger

■

Portable Instruments or Consumer Products

■

Battery-Powered Diagnostics and Control

■

Back-Up Battery Management

, LTC and LT are registered trademarks of Linear Technology Corporation.

The LTC

4010 provides a complete, cost-effective nickel

battery fast charge solution in a small package using few

external components. A 550kHz PWM current source

controller and all necessary charge initiation, monitoring

and termination control circuitry are included.

The LTC4010 automatically senses the presence of a DC

adapter and battery insertion or removal. When an exter-

nal DC source is not present, the LTC4010 enters shut-

down and supply current drawn from an installed battery

drops to the lowest possible level. Heavily discharged

batteries are precharged with a trickle current. The LTC4010

can simultaneously use both –∆V and ∆T/∆t fast charge

termination techniques and can detect various battery

faults. If necessary, a top-off charge is automatically

applied to NiMH batteries after fast charging is completed.

The IC will also resume charging if the battery self-

discharges after a full charge cycle.

All LTC4010 charging operations are qualified by actual

charge time and maximum average cell voltage. Charging

may also be gated by minimum and maximum tempera-

ture limits. NiMH or NiCd fast charge termination param-

eters are pin selectable.

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

2A NiMH Battery Charger

TIME (MINUTES)

1.0

AVERAGE CELL VOLTAGE (V)

CELL CASE TEMPERATURE (°C)

1.2

1.4

1.6

1.8

2.2

10 20 30 40

4011 TA01b

50 60

2.0

TOP OFF

CHARGE

Typical NiMH Charge at 1.25C

FAULT

CHRG

READY

TGATE

CDIV

CELL

TEMP

LTC4010

TIMER

INTV

GND

CHEM

SENSE

BAT

FROM

ADAPTER

5.5V TO 34V

10µH

SYSTEM

LOAD

0.05Ω

2-CELL

NiMH PACK

WITH 10k NTC

4010 TA01a

49.9k

10k 10k

0.1µF68nF

10µF

33nF

10µF

BGATE

PGND

Electrical Specifications Subject to Change

LTC4010

4010p

ORDER PART

NUMBER

(Note 1)

(Input Supply) to GND ....................... –0.3V to 40V

FAULT, CHRG, V

CELL

, V

CDIV

, BAT

or READY to GND .......................... –0.3V to V

+ 0.3V

SENSE to BAT ...................................................... ±0.3V

CHEM, V

TEMP

or TIMER to GND .............. –0.3V to 3.5V

PGND to GND ...................................................... ±0.3V

Current Sink: FAULT, CHRG or READY ................ 40mA

CDIV

Current Sink ............................................... 20mA

Output Current: BGATE to TGATE .................... ±200mA

Operating Ambient Temperature Range

(Note 2) .................................................. – 40°C to 85°C

Operating Junction Temperature (Note 3) ........... 125°C

Storage Temperature Range ................. – 65°C to 150°C

Lead Temperature (Soldering, 10 sec).................. 300°C

LTC4010EFE

JMAX

= 125°C, θ

= 38°C/W

EXPOSED PAD (PIN 17) IS GND. MUST BE SOLDERED TO

PCB TO OBTAIN SPECIFIED THERMAL RESISTANCE

ABSOLUTE MAXIMUM RATINGS

PACKAGE/ORDER INFORMATION

The ● indicates specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VCC = 12V, BAT = 4.8V, GND = PGND = 0V, unless otherwise noted.

Consult LTC Marketing for parts specified with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply

Input Voltage Range ●4.5 34 V

SHDN

Shutdown Quiescent Current V

= BAT = 4.8V ●510µA

Quiescent Current Waiting to Charge (Pause) ●3 4.5 mA

Operating Current Fast Charge State, No Gate Load ●57mA

UVLO

Undervoltage Threshold Voltage V

Increasing ●4.15 4.25 4.35 V

UV(HYST)

Undervoltage Hysteresis Voltage 170 mV

SHDNI

Shutdown Threshold Voltage DCIN – V

, DCIN Increasing ●45 65 90 mV

SHDND

Shutdown Threshold Voltage DCIN – V

, DCIN Decreasing ●15 25 38 mV

Charge Enable Threshold Voltage V

– BAT, V

Increasing ●455 545 mV

INTV

Regulator

Output Voltage No Load ●4.5 5 5.5 V

Short-Circuit Current (Note 5) INTV

= 0V ●28 50 100 mA

INTV

DD(MIN)

Output Voltage V

= 4.5V, I

= –10mA ●3.85 V

PWM Current Source

BAT – SENSE Full-Scale Regulation 0.3V < BAT < V

– 0.1V, 0°C < T

< 50°C●95 100 105 mV

Voltage (Fast Charge)

BAT – SENSE Precharge Regulation 0.3V < BAT < V

– 0.1V, 0°C < T

< 50°C●17 20 23 mV

Voltage

BAT – SENSE Top-Off Charge 0.3V < BAT < V

– 0.1V, 0°C < T

< 50°C●7.5 10 12.5 mV

Regulation Voltage

FE PACKAGE

16-LEAD PLASTIC TSSOP

TOP VIEW

FAULT

CHRG

CHEM

GND

TEMP

CELL

CDIV

TIMER

READY

TGATE

PGND

BGATE

INTV

BAT

SENSE

LTC4010

4010p

The ● indicates specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VCC = 12V, BAT = 4.8V, GND = PGND = 0V, unless otherwise noted.

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

∆V

BAT – SENSE Line Regulation 5.5V < V

< 34V, Fast Charge ●1 TBD mV

BAT

BAT Input Bias Current 0.3V < BAT < V

– 0.1V –2 0 2 mA

SENSE

SENSE Input Bias Current SENSE = BAT 50 150 µA

OFF

Input Bias Current SENSE or BAT, V

CELL

= 0V ●–1 0 1 µA

TYP

Typical Switching Frequency ●485 550 615 kHz

MIN

Minimum Switching Frequency ●20 30 kHz

MAX

Maximum Duty Cycle 98 99 %

OL(TG)

TGATE Output Voltage Low (Note 6) V

≥ 9V, No Load (V

– TGATE) ●5.35 6.3 8.75 V

≤ 7.5V, No Load ●50 mV

OH(TG)

TGATE Output Voltage High V

– TGATE, No Load ●050mV

R(TG)

TGATE Rise Time C

LOAD

= 3nF, 10% to 90% 35 50 ns

F(TG)

TGATE Fall Time C

LOAD

= 3nF, 10% to 90% 45 100 ns

OL(BG)

BGATE Output Voltage Low No Load ●050mV

OH(BG)

BGATE Output Voltage High No Load ●INTV

INTV

– 0.05

R(BG)

BGATE Rise Time C

LOAD

= 1.6nF, 10% to 90% 30 65 ns

F(BG)

BGATE Fall Time C

LOAD

= 1.6nF, 10% to 90% 10 25 ns

ADC Inputs

LEAK

Analog Channel Leakage 0V < V

CELL

< 2V, 0V < V

TEMP

< 2V ±100 nA

Charger Thresholds

Battery Present Threshold Voltage ●340 350 360 mV

BOV

Battery Overvoltage ●1.9 1.95 2 V

MFC

Minimum Fast Charge Voltage ●875 900 925 mV

FCBF

Fast Charge Battery Fault Voltage ●1.17 1.22 1.27 V

∆V

V(TERM)

–∆V Termination CHEM = Open (NiCd) ●18 20 22.0 mV

CHEM = 0V (NiMH) ●8.5 10 11.5 mV

Automatic Recharge Voltage V

CELL

Decreasing ●1.275 1.325 1.375 V

∆V

T(TERM)

∆T Termination (Note 7) CHEM = Open (NiCd) ●1.84 2 2.16 °C/MIN

CHEM = 0V (NiMH) ●0.86 1 1.14 °C/MIN

T(MIN)

Minimum Charging Temperature V

TEMP

Increasing ●357°C

(Note 7)

T(MAXI)

Maximum Charge Initiation V

TEMP

Decreasing, Not Charging ●43 45 47 °C

Temperature (Note 7)

T(MAXC)

Maximum Charging Temperature V

TEMP

Decreasing, Charging ●58 60 62 °C

(Note 7)

TEMP(D)

TEMP

Disable Threshold Voltage ●2.85 3.3 V

TEMP(P)

Pause Threshold Voltage ●160 280 mV

Charger Timing

∆t

TIMER

Internal Time Base Error ●–10 10 %

∆t

MAX

Programmable Timer Error R

TIMER

= 49.9k ●–15 15 %

LTC4010

4010p

The ● indicates specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VCC = 12V, BAT = 4.8V, GND = PGND = 0V, unless otherwise noted.

ELECTRICAL CHARACTERISTICS

Note 1: Absolute Maximum Ratings are those values beyond which the life

of the device may be impaired.

Note 2: The LTC4010E is guaranteed to meet performance specifications

from 0°C to 70°C. Specifications over the –40°C to 85°C operating

temperature range are assured by design, characterization and correlation

with statistical process controls.

Note 3: Operating junction temperature T

(in °C) is calculated from the

ambient temperature T

and the total continuous package power

dissipation P

(in watts) by the formula:

= T

+ θ

• P

Refer to the Applications Information section for details. This IC includes

overtemperature protection that is intended to protect the device during

momentary overload conditions. Junction temperature will exceed 125°C

when overtemperature protection is active. Continuous operation above

the specified maximum operating junction temperature may result in

device degradation or failure.

Note 4: All current into device pins are positive. All current out of device

pins are negative. All voltages are referenced to GND, unless otherwise

specified.

Note 5: Output current may be limited by internal power dissipation. Refer

to the Applications Information section for details.

Note 6: Either specified output may apply for 7.5V < V

< 9V.

Note 7: These limits apply specifically to the thermistor network shown in

Figure 5 in the Applications Information section and are guaranteed by

specific V

TEMP

voltage measurements during test.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Status and Chemistry Select

Output Voltage Low All Status Outputs and V

CDIV

, I

LOAD

= 10mA ●300 600 mV

LKG

Output Leakage Current All Status Outputs Inactive, V

OUT

= V

●–10 10 µA

IH(VCDIV)

Input Current High V

CDIV

= V

BAT

(Shutdown) ●–1 1 µA

Input Voltage Low CHEM (NiMH) ●900 mV

Input Voltage High CHEM (NiCd) ●2.85 V

Input Current Low CHEM = GND ●–20 –5 µA

Input Current High CHEM = 3.3V ●–20 20 µA

LTC4010

4010p

TYPICAL PERFOR A CE CHARACTERISTICS

Typical NiMH Charge Cycle

at 1C NiCd Charge at 2C NiMH Charge at 0.6C

Charger Efficiency at DCIN = 20V,

IOUT = 2A Charge Current Accuracy Charger Soft-Start

Fast Charge Current Line

Regulation PowerPath Switching

Fast Charge Current Output

Regulation

TIME (MINUTES)

CELL VOLTAGE (V)

BATTERY TEMPERATURE (°C)

1.50

1.55

1.60

4010 G01

1.45

1.40

20 40 80

1.35

1.30

1.65

CHARGE CURRENT

BATTERY

TEMPERATURE

SINGLE CELL

VOLTAGE

BATTERY VOLTAGE (V)

EFFICIENCY (%)

100

4010 G04

4 8 12 20142 6 10 18

TEMPERATURE (°C)

–12

CURRENT ERROR (%)

–8

–4

–10

–6

–2

10 20 30 40

4010 G05

500

FAST CHARGE

PRECHARGE

= 12V

BAT = 4.8V

200µs/DIV

VOLTAGE (V)

4010 G06

TGATE

BGATE

FAST CHARGE CURRENT

PRECHARGE CURRENT

(V)

–3

CURRENT ERROR (%)

–2

–1

10 14 18 22

4010 G07

26 30

50°C

25°C

0°C

BAT = 4.8V

BAT (V)

–3

CURRENT ERROR (%)

–2

4010 G08

–1

12 16

50°C

25°C

0°C

VCC = 20V

VOLTAGE (V)

4010 G09

100µs/DIV

DC674A WITH 1kΩ SYSTEM LOAD AND 20kΩ

DCIN SHUNT, CHARGER PAUSED

INFET

DCIN

DCIN OPEN

LTC4010

4010p

PI FU CTIO S

FAULT (Pin 1): Active-Low Fault Indicator Output. The

LTC4010 indicates various battery and internal fault con-

ditions by connecting this pin to GND. Refer to the Opera-

tion and Applications Information sections for further

details. This output is capable of driving an LED and should

be left floating if not used. FAULT is an open-drain output

to GND with an operating voltage range of GND to V

CHRG (Pin 2): Active-Low Charge Indicator Output. The

LTC4010 indicates it is providing charge to the battery by

connecting this pin to GND. Refer to the Operation and

Applications Information sections for further details. This

output is capable of driving an LED and should be left

floating if not used. CHRG is an open-drain output to GND

with an operating voltage range of GND to V

CHEM (Pin 3): Battery Chemistry Selection Input. This pin

should be wired to GND to select NiMH fast charge

termination parameters. If a voltage greater than 2.85V is

applied to this pin, or it is left floating, NiCd parameters are

used. Refer to the Applications Information section for

further details. Operating voltage range is GND to 3.3V.

GND (Pin 4): Ground. This pin provides a single-point

ground for internal references and other critical analog

circuits.

TEMP

(Pin 5): Battery Temperature Input. An external

10k NTC thermistor may be connected between V

TEMP

and GND to provide temperature-based charge qualifica-

tion and additional fast charge termination control. Charg-

ing may also be paused by connecting the V

TEMP

pin to

GND. Refer to the Operation and Applications Informa-

tion sections for complete details on external thermistor

networks and charge control. If this pin is not used it

should be wired to INTV

through 56k. Operating volt-

age range is GND to 3.3V.

CELL

(Pin 6): Average Single-Cell Voltage Input. An

external voltage divider between BAT and V

CDIV

is attached

to this pin to monitor the average single-cell voltage of the

battery pack. The LTC4010 uses this information to pro-

tect against catastrophic battery overvoltage and to con-

trol the charging state. Refer to the Applications Information

section for further details on the external divider network.

Operating voltage range is GND to BAT.

CDIV

(Pin 7): Average Cell Voltage Resistor Divider Ter-

mination. The LTC4010 connects this pin to GND provided

the charger is not in shutdown. V

CDIV

is an open-drain

output to GND with an operating voltage range of GND to

BAT.

TIMER (Pin 8): Charge Timer Input. A resistor connected

between TIMER and GND programs charge cycle timing

limits. Refer to the Applications Information section for

complete details. Operating voltage range is GND to 1V.

SENSE (Pin 9): Charge Current Sense Input. An external

resistor between this input and BAT is used to program

charge current. Refer to the Applications Information

section for complete details on programming charge

current. Operating voltage ranges from (BAT – 50mV) to

(BAT + 200mV).

BAT (Pin 10): Battery Pack Connection. The LTC4010 uses

the voltage on this pin to control current sourced from V

to the battery during charging. Allowable operating volt-

age range is GND to V

INTV

(Pin 11): Internal 5V Regulator Output. This pin

provides a means of bypassing the internal 5V regulator

used to power the BGATE output driver. Typically, power

should not be drawn from this pin by the application

circuit. Refer to the Application Information section for

additional details.

BGATE (Pin 12): External Synchronous N-channel MOSFET

Gate Control Output. This output provides gate drive to an

optional external NMOS power transistor switch used for

synchronous rectification to increase efficiency in the

step-down DC/DC converter. Operating voltage is GND to

INTV

. BGATE should be left floating if not used.

PGND (Pin 13): Power Ground. This pin provides a return

for switching currents generated by internal LTC4010

circuits. Externally, PGND and GND should be wired

together using a very low impedance connection. Refer to

PCB Layout Considerations in the Applications Informa-

tion section for additional grounding details.

LTC4010

4010p

TGATE (Pin 14): External P-channel MOSFET Gate Control

Output. This output provides gate drive to an external

PMOS power transistor switch used in the DC/DC con-

verter. Operating voltage range varies as a function of V

Refer to the Electrical Characteristics table for specific

voltages.

(Pin 15): Power Input. External diodes normally con-

nect either the DC input power supply or the battery to this

pin. Refer to the Applications Information section for fur-

ther details. Suggested applied voltage range is GND to 34V.

PI FU CTIO S

READY (Pin 16): Active-Low Ready-to-Charge Output.

The LTC4010 connects this pin to GND if proper operating

voltages for charging are present. Refer to the Operation

section for complete details on charge qualification. This

output is capable of driving an LED and should be left

floating if not used. READY is an open-drain output to GND

with an operating voltage range of GND to V

Exposed Pad (Pin 17): This pin provides enhanced

thermal properties for the TSSOP. It must be soldered to

the PCB copper ground to obtain optimum thermal

performance.

BLOCK DIAGRA

CHARGER

STATE

CONTROL

LOGIC

THERMISTOR

INTERFACE

A/D

CONVERTER

BATTERY

DETECTOR

VOLTAGE

REGULATOR

UVLO AND

SHUTDOWN

PWM

CHARGE

TIMER

VOLTAGE

REFERENCE

INTERNAL

VOLTAGE

REGULATOR

TEMP

CHEM

2CHRG

1FAULT

GND

CELL

8TIMER

CDIV

INTV

4010 BD

BAT

SENSE

BGATE

READY

PGND

TGATE

LTC4010

4010p

Figure 1. LTC4010 State Diagram

CHARGE

QUALIFICATION

SHUTDOWN

DC ADAPTER PRESENT

NiCd OR

NiMH – ∆V

CELL

< 1.325V

MAX

IS PROGRAMMED MAXIMUM FAST CHARGE DURATION

**OPTIONAL TEMPERATURE LIMITS APPLY

4010 F01

CELL

< 900mV

CELL

> 900mV

CELL

> 900mV

CELL

< 900mV

CELL

< 1.22V

AT t

MAX

*/12

OR TIME = t

MAX

CELL

> 350mV, ADEQUATE V

CHARGER ENABLED AND

TEMPERATURE OK (OPTIONAL)

CHECK

BATTERY

PRECHARGE**

(C/5 FOR

MAX

/12)

FAST CHARGE**

(1C)

AUTOMATIC

RECHARGE

FAULT

CELL

> 1.95V

OR PWM FAULTS

TOP-OFF

CHARGE**

(C/10)

NiMH

∆T/∆t

NO DC ADAPTER

MAX

NO BATTERY

< 4.25V

Shutdown State

The LTC4010 remains in micropower shutdown until V

(Pin 15) is driven above BAT (Pin 10). In shutdown all

status and PWM outputs and internally generated supply

voltages are inactive. Current consumption from V

and

BAT is reduced to a very low level.

Charge Qualification State

Once V

is greater than BAT, the LTC4010 exits mi-

cropower shutdown, enables its own internal supplies and

switches V

CDIV

to GND to allow measurement of the

average single-cell voltage. The IC also verifies that V

at or above 4.25V, V

is 500mV above BAT and V

CELL

between 350mV and 1.95V. If V

CELL

is above 1.95V, the

fault state is entered, which is described in more detail

below. Once adequate voltage conditions exist for charg-

ing, READY is asserted.

If the voltage between VTEMP and GND is below 200mV,

the LTC4010 is paused. If VTEMP is above 200mV but

below 2.85V, the LTC4010 verifies that the sensed

temperature is between 5°C and 45°C. If these tempera-

ture limits are not met or if its own die temperature is too

high, the LTC4010 will indicate a fault and not allow

charging to begin. If VTEMP is greater than 2.85V, battery

temperature related charge qualification, monitoring and

termination are disabled.

Once charging is fully qualified, precharge begins (unless

the LTC4010 is paused). In that case, the V

TEMP

pin is

monitored for further control. The charge status indicators

and PWM outputs remain inactive until charging begins.

Charge Monitoring

The LTC4010 continues to monitor important voltage and

temperature parameters during all charging states. If V

drops to the BAT voltage or lower, charging stops and the

shutdown state is entered. If V

drops below 4.25V or

CELL

drops below 350mV, charging stops and the LTC4010

returns to the charge qualification state. If V

CELL

exceeds

1.95V, charging stops and the IC enters the fault state. If

an external thermistor indicates sensed temperature is

OPERATIO

(Refer to Figure 1)

LTC4010

4010p

OPERATIO

beyond a range of 5°C to 60°C, or the internal die tempera-

ture exceeds a resonable value, charging is suspended,

the charge timer is paused and the LTC4010 indicates a

fault condition. Normal charging resumes from the previ-

ous state when the sensed temperature returns to a satis-

factory range. In addition, other battery faults are detected

during specific charging states as described below.

Precharge State

If the initial voltage on V

CELL

is below 900mV, the LTC4010

enters the precharge state and enables the PWM current

source to trickle charge using one-fifth the programmed

charge current. The CHRG status output is active during

precharge. The precharge state duration is limited to

MAX

/12 minutes, where t

MAX

is the maximum fast charge

period programmed with the TIMER pin. If sufficient V

CELL

voltage cannot be developed in this length of time, the fault

state is entered, otherwise fast charge begins.

Fast Charge State

If adequate average single-cell voltage exists, the LTC4010

enters the fast charge state and begins charging at the

programmed current set by the external current sense

resistor connected between the SENSE and BAT pins. The

CHRG status output is active during fast charge. If V

CELL

is initially above 1.325V, cell voltage processing begins

immediately. Otherwise –∆V termination is disabled for a

stabilization period of t

MAX

/12. In that case, the LTC4010

makes another fault check at t

MAX

/12, requiring the aver-

age cell voltage to be above 1.22V. This ensures the

battery pack is accepting a fast charge. If V

CELL

is not

above this voltage threshold, the fault state is entered. Fast

charge state duration is limited to t

MAX

and the fault state

is entered if this limit is exceeded.

Charge Termination

Fast charge termination parameters are dependent upon

the battery chemistry selected with the CHEM pin. Volt-

age-based termination (–∆V) is always active after the

initial voltage stabilization period. If an external thermistor

network is present, chemistry-specific limits for ∆T/∆t

(rate of temperature rise) are also used in the termination

algorithm. Temperature-based termination, if enabled,

becomes active as soon as the fast charge state is entered.

(Refer to Figure 1)

Top-Off Charge State

If NiMH fast charge termination occurs because the ∆T/∆t

limit is exceeded after an initial period of t

MAX

/12 has ex-

pired, the LTC4010 enters the top-off charge state. Top-off

charge is implemented by sourcing one-tenth the pro-

grammed charge current for t

MAX

/3 minutes to ensure that

100% charge has been delivered to the battery. The CHRG

status output is active during the top-off state. If NiCd cells

have been selected with the CHEM pin, the LTC4010 never

enters the top-off state.

Automatic Recharge State

Once charging is complete, the automatic recharge state

is entered to address the self-discharge characteristics of

nickel chemistry cells. The charge status output is inactive

during automatic recharge, but V

CDIV

remains switched to

GND to monitor the average cell voltage. If the V

CELL

voltage drops below 1.325V without falling below 350mV,

the charge timer is reset and a new fast charge cycle is

initiated.

The internal termination algorithms of the LTC4010 are

adjusted when a fast charge cycle is initiated from auto-

matic recharge, because the battery should be almost fully

charged. Voltage-based termination is enabled immedi-

ately and the NiMH ∆T/∆t limit is fixed at a battery

temperature rise of 1°C/minute.

Fault State

As discussed previously, the LTC4010 enters the fault

state based on detection of invalid battery voltages during

various charging phases. The IC also monitors the regu-

lation of the PWM control loop and will enter the fault state

if this is not within acceptable limits. Once in the fault state,

the battery must be removed or DC input power must be

cycled in order to initiate further charging. In the fault

state, the FAULT output is active, the READY output is

inactive, charging stops and the charge indicator output is

inactive. The V

CDIV

output remains connected to GND to

allow detection of battery removal.

Note that the LTC4010 also uses the FAULT output to

indicate that charging is suspended due to invalid battery

or internal die temperatures. However, the IC does not

enter the fault state in these cases and normal operation

LTC4010

4010p

will resume when all temperatures return to acceptable

levels. Refer to the Status Outputs section for more detail.

Insertion and Removal of Batteries

The LTC4010 automatically senses the insertion or re-

moval of a battery by monitoring the V

CELL

pin voltage.

Should this voltage fall below 350mV, the IC considers the

battery to be absent. Removing and then inserting a

battery causes the LTC4010 to initiate a completely new

charge cycle beginning with charge qualification.

External Pause Control

After charging is initiated, the V

TEMP

pin may be used to

pause operation at any time. When the voltage between

TEMP

and GND drops below 200mV, the charge timer

pauses, fast charge termination algorithms are inhibited

and the PWM outputs are disabled. The status and V

CDIV

outputs all remain active. Normal function is fully restored

from the previous state when pause ends.

Status Outputs

The LTC4010 open-drain status outputs provide valuable

information about the IC’s operating state and can be

used for a variety of purposes in applications. Table 1

summarizes the state of the three status outputs and the

VCDIV pin as a function of LTC4010 operation. The status

outputs can directly drive current-limited LEDs termi-

nated to the DC input. The VCDIV column in Table 1 is

strictly informational. VCDIV should only be used to termi-

nate the VCELL resistor divider, as previously discussed.

PWM Current Source Controller

An integral part of the LTC4010 is the PWM current source

controller. The charger uses a synchronous step-down

architecture to produce high efficiency and limited thermal

dissipation. The nominal operating frequency of 550kHz

allows use of a smaller external inductor. The TGATE and

BGATE outputs have internally clamped voltage swings.

They source peak currents tailored to smaller surface-

mount power FETs likely to appear in applications provid-

ing an average charge current of 3A or less. During the

various charging states, the LTC4010 uses the PWM

controller to regulate an average voltage between SENSE

and BAT that ranges from 10mV to 100mV.

A conceptual diagram of the LTC4010 PWM control loop

is shown in Figure 2.

The voltage across the external current programming

resistor R

SENSE

is averaged by integrating error amplifier

EA. An internal programming current is also pulled from

input resistor R1. The I

PROG

• R1 product establishes the

desired average voltage drop across R

SENSE

, and hence,

the average current through R

SENSE

. The I

output of the

error amplifier is a scaled control current for the input of

the PWM comparator CC. The I

• R3 product sets a peak

OPERATIO

Table 1. LTC4010 Status Pins

READY FAULT CHRG V

CDIV

CHARGER STATE

Off Off Off Off Off

On Off Off On Ready to Charge

TEMP

Held Low)

or Automatic Recharge

On Off On On Precharge, Fast or Top Off

Charge (May be Paused)

On On On or Off On Temperature Limits

Exceeded

Off On Off On Fault State (Latched) Figure 2. LTC4010 PWM Control Loop

–

ITH

IPROG

QPWM CLOCK

BAT

9SENSE

RSENSE

12 BGATE

14 TGATE

LTC4010

VCC

4010 F02

LTC4010

4010p

current threshold for CC such that the desired average

current through R

SENSE

is maintained. The current com-

parator output does this by switching the state of the SR

latch at the appropriate time.

the beginning of each oscillator cycle, the PWM clock

sets the SR latch and the external P

-channel

MOSFET is

switched on (N

-channel

MOSFET switched off) to refresh

the current carried by the external inductor. The inductor

current and voltage drop across RSENSE begin to rise

linearly. During normal operation, the PFET is turned off

(NFET on) during the cycle by CC when the voltage

difference across RSENSE reaches the peak value set by

the output of EA. The inductor current then ramps down

linearly until the next rising PWM clock edge. This closes

the loop and maintains the desired average charge current

in the external inductor.

Low Dropout Charging

After charging is initiated, the LTC4010 does not require

that V

remain at least 500mV above BAT because

situations exist where low dropout charging might occur.

OPERATIO

In one instance, parasitic series resistance may limit PWM

headroom (between V

and BAT) as 100% charge is

reached. A second case can arise when the DC adapter

selected by the end user is not capable of delivering the

current programmed by R

SENSE

, causing the output volt-

age of the adapter to collapse. While in low dropout, the

LTC4010 PWM runs near 100% duty cycle with a fre-

quency that may not be constant and can be less than

550kHz. The charge current will drop below the pro-

grammed value to avoid generating audible noise, so the

actual charge delivered to the battery may depend prima-

rily on the LTC4010 charge timer.

Internal Die Temperature

The LTC4010 provides internal overtemperature detec-

tion to protect against electrical overstress, primarily at

the FET driver outputs. If the die temperature rises above

this thermal limit, the LTC4010 stops switching and

indicates a fault as previously discussed.

APPLICATIO S I FOR ATIO

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External DC Source

The external DC power source should be connected to the

charging system and the V

pin through a power diode

acting as an input rectifier. This prevents catastrophic

system damage in the event of reverse-voltage polarity at

the DC input. The LTC4010 automatically senses when

this input drives the V

pin above BAT. The open-circuit

voltage of the DC source should be between 5.5V and 34V,

depending on the number of cells being charged. In order

to avoid low dropout operation, ensure 100% capacity at

charge termination, and allow reliable detection of battery

insertion, removal or overvoltage, the following equation

can be used to determine the minimum full-load voltage

that should be produced at V

when the external DC

power source is connected.

CC(MIN)

= (n • 2V) + 0.3V

where n is the number of series cells in the battery pack.

The LTC4010 will properly charge over a wide range of V

and BAT voltage combinations. Operating the LTC4010 in

low dropout or with V

much greater than BAT will force

the PWM frequency to be much less than 550kHz. The

LTC4010 disables charging and sets a fault if a large V

to BAT differential would cause generation of audible noise.

Load Control

Proper current load control is an important consideration

when fast charging nickel cells. This control ensures that

the system load remains powered at all times, but that

normal system operation and associated load transients

do not adversely affect fast charge termination. The input

protecton detailed in the previous paragraph is an integral

part of the necessary load control.

The battery should also be connected to the raw system

supply by some rectifying means, thus forming a switch that

LTC4010

4010p

APPLICATIO S I FOR ATIO

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selects the battery for system power only if an external DC

source is not present.

Battery Chemistry Selection

The desired battery chemistry is selected by programming

the CHEM pin to the proper voltage. If it is wired to GND,

a set of parameters specific to charging NiMH cells is

selected. When CHEM is left floating, charging is opti-

mized for NiCd cells. The various charging parameters are

detailed in Table 2.

Programming Charge Current

Charge current is programmed using the following

equation:

RmV

SENSE PROG

=100

SENSE

is an external resistor connected between the

SENSE and BAT pins. A 1% resistor with a low temperature

coefficient and sufficient power dissipation capability to

avoid self-heating effects is recommended.

Programming Maximum Charge Times

Connecting the appropriate resistor between the TIMER

pin and GND programs the maximum duration of various

charging states. To some degree, the value should reflect

how closely the programmed charge current matches the

1C rate of targeted battery packs. The maximum fast

charge period is determined by the following equation:

Rt Hours

TIMER MAX

=Ω

()

•

–

30 10

Some typical timing values are detailed in Table 3. R

TIMER

should not be less than 15k. The actual time limits used by

the LTC4010 have a resolution of approximately ±30

seconds in addition to the tolerances given the Electrical

Characteristics table. The maximum time period is ap-

proximately 4.3 hours.

Table 2. LTC4010 Charging Parameters

CHEM BAT

STATE PIN CHEMISTRY TIMER T

MIN

MAX

CHRG

TERMINATION CONDITION

PC Both t

MAX

/12 5°C45°CI

PROG

/5 Timer Expires

FC Open NiCd t

MAX

5°C60°CI

PROG

–20mV per Cell or 2°C/Minute

GND NiMH t

MAX

5°C60°CI

PROG

1.5°C/Minute for First t

MAX

/12 Minutes if Initial

CELL

< 1.325V

–10mV per Cell or 1°C/Minute After t

MAX

/12 Minutes

or if Initial V

CELL

> 1.325V

TOC GND NiMH t

MAX

/3 5°C60°CI

PROG

/10 Timer Expires

AR Both 5°C45°C0V

CELL

< 1.325V

PC: Precharge

FC: Fast Charge (Initial –∆V Termination Hold Off of t

MAX

/12 Minutes May Apply)

TOC: Top-Off Charge (Only for NiMH ∆T/∆t FC Termination After Initial t

MAX

/12 Period)

AR: Automatic Recharge (Temperature Limits Apply to State Termination Only)

Table 3. LTC4010 Time Limit Programming Examples

FAST CHARGE TOP-OFF

TYPICAL FAST PRECHARGE LIMIT VOLTAGE STABILIZATION FAST CHARGE LIMIT CHARGE

TIMER

CHARGE RATE (MINUTES) (MINUTES) (HOURS) (MINUTES)

24.9k 2C 3.8 3.8 0.75 15

33.2k 1.5C 5 5 1 20

49.9k 1C 7.5 7.5 1.5 30

66.5k 0.75C 10 10 2 40

100k C/2 15 15 3 60

LTC4010

4010p

Cell Voltage Network Design

An external resistor network is required to provide the

average single-cell voltage to the V

CELL

pin of the LTC4010.

The proper circuit for multicell packs is shown in Figure 3.

The ratio of R2 to R1 should be a factor of (n – 1), where

n is the number of series cells in the battery pack. The value

of R1 should be between 1k and 100k. This range limits the

sensing error caused by V

CELL

leakage current and pre-

vents the ON resistance of the internal NFET between V

CDIV

and GND from causing a significant error in the V

CELL

voltage. The external resistor network is also used to

detect battery insertion and removal. The filter formed by

C1 and the parallel combination of R1 and R2 is recom-

mended for rejecting PWM switching noise. The value of

C1 should be chosen to yield a 1st order lowpass fre-

quency of less than 500Hz. In the case of a single cell, the

external application circuit shown in Figure 4 is recom-

mended to provide the necessary noise filtering and miss-

ing battery detection.

APPLICATIO S I FOR ATIO

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best with a 1% 10k NTC thermistor with a β of 3750.

However, the LTC4010 will operate satisfactorily with

other 10k NTC thermistors having slightly different nomi-

nal exponential temperature coefficients. For these ther-

mistors, the temperature related limits given in the Electri-

cal Characteristics table may not strictly apply. The filter

formed by C1 in Figure 5 is optional but recommended for

rejecting PWM switching noise.

Figure 4. Single-Cell Monitor Network

Figure 3. Multiple Cell Voltage Divider

BAT

LTC4010 R2 +

FOR TWO OR

MORE SERIES CELLS

R1 C1

R2 = R1(n – 1)

4010 F03

CDIV

GND

CELL

BAT

10k 10k

33nF

1 CELL

4010 F04

VCDIV

6VCELL

External Thermistor

The network for proper temperature sensing using a

thermistor with a negative temperature coefficient (NTC)

is shown in Figure 5. The LTC4010 is designed to work

Figure 5. External NTC Thermistor Network

TEMP

10k NTC

68nF

4010 F05

Disabling Thermistor Functions

Temperature sensing is optional in LTC4010 applications.

For low cost systems where temperature sensing may not

be required, the V

TEMP

pin may simply be wired to INTV

through 56k to disable temperature qualification of all

charging operations. However, this practice is not recom-

mended for NiMH cells charged well above or below their

1C rate, because fast charge termination based solely on

voltage inflection may not be adequate to protect the

battery from a severe overcharge.

INTV

Regulator Output

If BGATE is left open, the INTV

pin of the LTC4010 can

be used as an additional source of regulated voltage in the

host system any time READY is active. Switching loads on

INTV

may reduce the accuracy of internal analog cir-

cuits used to monitor and terminate fast charging. In

addition, DC current drawn from the INTV

pin can

greatly increase internal power dissipation at elevated V

voltages. A minimum ceramic bypass capacitor of 0.1µF is

recommended.

Calculating Average Power Dissipation

The user should ensure that the maximum rated IC junc-

tion temperature is not exceeded under all operating con-

ditions. The thermal resistance of the LTC4010 package

(θ

) is 38°C/W, provided the exposed metal pad is prop-

erly soldered to the PCB. The actual thermal resistance in

LTC4010

4010p

APPLICATIO S I FOR ATIO

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Application on the first page of this data sheet, these

figures demonstrate some of the proper configurations

of the LTC4010. MOSFET body diodes are shown in these

figures strictly for reference only.

Figure 6 shows a minimum application, which might be

encountered in low cost NiCd fast charge applications. The

LTC4010 uses –∆V to terminate the fast charge state, as

no external temperature information is available.

Nonsynchronous PWM switching is employed to reduce

external component cost. A single LED indicates charging

status.

A full-featured 2A LTC4010 application is shown in Fig-

ure 7. The inherent voltage ratings of the V

CELL

, V

CDIV

SENSE and BAT pins allow charging of from one to sixteen

series nickel cells in this application, governed only by the

overhead limits previously discussed. The application

includes all average cell voltage and battery temperature

sensing circuitry required for the LTC4010 to utilize its full

range of charge qualification, safety monitoring and fast

charge termination features. The V

TEMP

thermister net-

work allows the LTC4010 to accurately terminate fast

charge under a variety of applied charge rates. Use of a

synchronous PWM topology improves efficiency and re-

duces excess heat generation. A green LED indicates valid

DC input voltage and installed battery, while a red LED

indicates charging. Fault conditions are indicated by a

yellow LED. The grounded CHEM pin selects the NiMH

charge termination parameter set.

the application will depend on the amount of PCB copper

to which the package is soldered. Feedthrough vias di-

rectly below the package that connect to inner copper

layers are helpful in lowering thermal resistance. The fol-

lowing formula may be used to estimate the maximum

average power dissipation P

(in watts) of the LTC4010

under normal operating conditions.

PV mAI kQ Q

D CC DD TGATE BGATE

DD CC LED

LED

=++ +

()

⎛

⎝

⎜⎞

⎠

⎟

7 3 615

385 60 30

.()

–. –

where:

= Average external INTV

load current, if any

TGATE

= Gate charge of external P-channel MOSFET

in coulombs

BGATE

= Gate charge of external N-channel MOSFET

(if used) in coulombs

LED

= Maximum external LED forward voltage

LED

= External LED current-limiting resistor used in

the application

n = Number of LEDs driven by the LTC4010

Sample Applications

Figures 6 through 8 detail sample charger applications

of various complexities. Combined with the Typical

Figure 6. Minimum LTC4010 Application

FAULT

CHRG

READY

TGATE

CDIV

CELL

CHEM

TEMP

LTC4010

TIMER

INTV

GND

SENSE

BAT

FROM

ADAPTER

5.5V TO 34V

10µH

SYSTEM

LOAD

0.1Ω

NiCd

PACK

4010 F06

49.9k

10k

56k

0.1µF

10µF

33nF

10µF

BGATE

PGND

LTC4010

4010p

P-channel MOSFET Q4 functions as a switch to connect

the battery to the system load whenever the DC input

adapter is removed. If the maximum battery voltage is less

than the maximum rated V

of Q4, diode D1 and resistor

R1 are not required. Otherwise choose the Zener voltage

of D1 to be less than the maximum rated V

of Q4. R1

provides a bias current of (V

BAT

– V

ZENER

)/(R1 + 20k) for

D1 when the input adapter is removed. Choose R1 to make

this current, which is drawn from the battery, just large

enough to develop the desired V

across D1.

While the LTC4010 is a complete, standalone solution,

Figure 8 shows that it can also be interfaced to a host mi-

croprocessor. The MCU can control the charger directly with

an open-drain I/O port connected to the V

TEMP

pin, if that

port is low leakage and can tolerate at least 2V. The charger

state is monitored on the three LTC4010 status outputs.

Charging of NiMH batteries is selected in this example.

However, NiCd parameters could be chosen as well.

Unlike all of the other applications discussed so far, the

battery continues to power the system during charging.

The MCU could be powered directly from the battery or

from any type of post regulator operating from the battery.

In this configuration, the LTC4010 relies expressly on the

ability of the host MCU to know when load transients will

be encountered. The MCU should then pause charging (and

thus –∆V processing) during those events to avoid pre-

mature fast charge termination. If the MPU cannot reliably

perform this function, the battery

should

be disconnected

from the load with a rectifier or switch during charging.

Excessive battery load current variations, such as those

generated by a post-regulating PWM, can generate suffi-

cient voltage noise to cause the LTC4010 to prematurely

terminate a charge cycle and/or prematurely restart a fast

charge. In this case, it may be necessary to inhibit the

LTC4010 after charging is complete until external gas gauge

circuitry indicates that recharging is necessary. Shutdown

power is applied to the LTC4010 through the body diode

of the P-channel MOSFET in this application.

Waveforms

Sample waveforms for a standalone application during a

typical charge cycle are shown in Figure 9. Note that these

waveforms are not to scale and do not represent the

complete range of possible activity. The figure is simply

intended to allow better conceptual understanding and to

highlight the relative behavior of certain signals generated

by the LTC4010 during a typical charge cycle.

Initially, the LTC4010 is in low power shutdown as the

system operates from a heavily discharged battery. A DC

adapter is then connected such that V

rises above 4.25V

APPLICATIO S I FOR ATIO

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Figure 7. Full-Featured 2A LTC4010 Application

FAULT

CHRG

READY

TGATE

CDIV

CELL

TEMP

LTC4010

TIMER

INTV

GND

CHEM

SENSE

BAT

FROM

ADAPTER

5.5V TO 34V

10µH

SYSTEM

LOAD

0.05Ω

NiMH PACK

WITH 10k NTC

4010 F07

49.9k

20k

10k

R1 10k

0.1µF68nF

20µF

33nF

20µF

BGATE

PGND

LTC4010

4010p

APPLICATIO S I FOR ATIO

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Figure 9. Charging Waveforms Example

Figure 8. LTC4010 with MCU Interface

FAULT

CHRG

READY

TGATE

CDIV

CELL

TEMP

LTC4010

TIMER

INTV

GND

CHEM

SENSE

BAT

FROM

ADAPTER

5.5V TO 34V

10µH

SYSTEM

LOAD

0.1Ω

NiCd PACK

WITH 10k NTC

4010 F08

49.9k

10k

0.1µF

PAUSE

FROM MCU

68nF

10µF

33nF

10µF

V+

BGATE

PGND

SHDN

VCC = 4.25VDCIN

READY

VCDIV

TGATE

VCELL

CHRG

VTEMP

(PAUSE)

SHDNTOP-OFF AUTO

RECHARGE

FAST CHARGEPRECHARGE

0.9V

EXTERNAL

PAUSE

200mV

4010 F09

LTC4010

4010p

APPLICATIO S I FOR ATIO

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and is 500mV above BAT. The READY output is asserted

when the LTC4010 completes charge qualification.

When the LTC4010 determines charging should begin, it

starts a precharge cycle because V

CELL

is less than 900mV.

As long as the temperature remains within prescribed

limits, the LTC4010 charges (TGATE switching), applying

limited current to the battery with the PWM in order to

bring the average cell voltage to 900mV.

When the precharge state timer expires, the LTC4010 be-

gins fast charge if V

CELL

is greater than 900mV. The PWM,

charge timer and internal termination control are sus-

pended if pause is asserted (V

CELL

< 200mV), but all status

outputs continue to indicate charging is in progress. The

fast charge state continues until the selected voltage or

temperature termination criteria are met. Figure 9 sug-

gests termination based on ∆T/∆t, which for NiMH would

be an increase of 1°C per minute.

Because NiMH charging terminated due to ∆T/∆t and the

fast charge cycle had lasted more than t

MAX

/12 minutes,

the LTC4010 begins a top-off charge with a current of

PROG

/10. Top-off is an internally timed charge of t

MAX

minutes with the CHRG output continuously asserted.

Finally, the LTC4010 enters the automatic recharge state

where the CHRG output is deasserted. The PWM is dis-

abled but V

CDIV

remains asserted to monitor V

CELL

. The

charge timer will be reset and fast charging will resume if

CELL

drops below 1.325V. The LTC4010 enters shutdown

when the DC adapter is removed, minimizing current draw

from the battery in the absence of an input power source.

While not a part of the sample waveforms of Figure 9,

temperature qualification is an ongoing part of the charg-

ing process, if an external thermistor network is detected

by the LTC4010. Should prescribed temperature limits be

exceeded during any particular charging state, charging

would be suspended until the sensed temperature re-

turned to an acceptable range.

Battery-Controlled Charging

Because of the programming arrangement of the LTC4010,

it may be possible to configure it for battery-controlled

charging. In this case, the battery pack is designed to

provide customized information to an LTC4010-based

charger, allowing a single design to service a wide range

of application batteries. Assume the charger is designed to

provide a maximum charge current of 800mA (R

SENSE

125mΩ). Figure 10 shows a 5V NiCd battery pack for

which 800mA represents a 0.75C rate. When connected to

the charger, this pack would provide battery temperature

information and correctly configure both fast charge ter-

mination parameters and time limits for the internal NiCd

cells.

A second possibility is to configure an LTC4010-based

charger to accept battery packs with varying numbers of

cells. By including R2 of the average cell voltage divider

network shown in Figure 3, battery-based programming

of the number of series-stacked cells could be realized

without defeating LTC4010 detection of battery insertion

or removal. Figure 11 shows a 2.5V NiMH battery pack that

programs the correct number of series cells when it is

connected to the charger, along with indicating chemistry

and providing temperature information.

Any of these battery pack charge control concepts could

be combined in a variety of ways to service custom

application needs.

Figure 10. NiCd Battery Pack with Time Limit Control

1200mAhr

NiCd CELLS

BATTERY

PACK

VTEMP

CHEM

TIMER

66.5k

4010 F10

–

10k

NTC

Figure 11. NiMH Battery Pack Indicating Number of Cells

1500mAhr

NiMH CELLS

BATTERY

PACK

TEMP

CELL

CHEM

4010 F11

–

10k

NTC

LTC4010

4010p

PCB Layout Considerations

To prevent magnetic and electrical field radiation and high

frequency resonant problems, proper layout of the com-

ponents connected to the LTC4010 is essential. Refer to

Figure 12. For maximum efficiency, the switch node rise

and fall times should be minimized. The following PCB

design priority list will help ensure proper topology. Lay-

out the PCB using this specific order.

1. Input capacitors should be placed as close as possible

to switching FET supply and ground connections with

the shortest copper traces possible. The switching

FETs must be on the same layer of copper as the input

capacitors. Vias should not be used to make these

connections.

2. Place the LTC4010 close to the switching FET gate

terminals, keeping the connecting traces short to

produce clean drive signals. This rule also applies to

IC supply and ground pins that connect to the switch-

ing FET source pins. The IC can be placed on the

opposite side of the PCB from the switching FETs.

3. Place the inductor input as close as possible to the

drain of the switching FETs. Minimize the surface area

of the switch node. Make the trace width the minimum

needed to support the programmed charge current.

Use no copper fills or pours. Avoid running the con-

nection on multiple copper layers in parallel. Minimize

capacitance from the switch node to any other trace or

plane.

4. Place the charge current sense resistor immediately

adjacent to the inductor output, and orient it such that

current sense traces to the LTC4010 are not long.

These feedback traces need to be run together as a

single pair with the smallest spacing possible on any

given layer on which they are routed. Locate any filter

component on these traces next to the LTC4010, and

not at the sense resistor location.

APPLICATIO S I FOR ATIO

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5. Place output capacitors next to the sense resisitor

output and ground.

6. Output capacitor ground connections must feed into

the same copper that connects to the input capacitor

ground before tying back into system ground.

7. Connection of switching ground to system ground, or

any internal ground plane should be single-point. If

the system has an internal system ground plane, a

good way to do this is to cluster vias into a single star

point to make the connection.

8. Route analog ground as a trace tied back to the

LTC4010 GND pin before connecting to any other

ground. Avoid using the system ground plane. A

useful CAD technique is to make analog ground a

separate ground net and use a 0Ω resistor to connect

analog ground to system ground.

9. A good rule of thumb for via count in a given high

current path is to use 0.5A per via. Be consistent when

applying this rule.

10. If possible, place all the parts listed above on the same

PCB layer.

11. Copper fills or pours are good for all power connec-

tions except as noted above in Rule 3. Copper planes

on multiple layers can also be used in parallel. This

helps with thermal management and lowers trace

inductance, which further improves EMI performance.

12. For best current programming accuracy, provide a

Kelvin connection from R

SENSE

to SENSE and BAT.

See Figure 13 for an example.

13. It is important to minimize parasitic capacitance on

the TIMER, SENSE and BAT pins. The traces connect-

ing these pins to their respective resistors should be

as short as possible.

LTC4010

4010p

PACKAGE DESCRIPTIO

FE Package

16-Lead Plastic TSSOP (4.4mm)

(Reference LTC DWG # 05-08-1663)

Exposed Pad Variation BC

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 represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

FE16 (BC) TSSOP 0204

0.09 – 0.20

(.0035 – .0079)

0° – 8°

0.25

REF

0.50 – 0.75

(.020 – .030)

4.30 – 4.50*

(.169 – .177)

134

5678

10 9

4.90 – 5.10*

(.193 – .201)

16 1514 13 12 11

1.10

(.0433)

MAX

0.05 – 0.15

(.002 – .006)

0.65

(.0256)

BSC

2.94

(.116)

0.195 – 0.30

(.0077 – .0118)

TYP

RECOMMENDED SOLDER PAD LAYOUT

0.45 ±0.05

0.65 BSC

4.50 ±0.10

6.60 ±0.10

1.05 ±0.10

2.94

(.116)

3.58

(.141)

3.58

(.141)

MILLIMETERS

(INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.150mm (.006") PER SIDE

NOTE:

1. CONTROLLING DIMENSION: MILLIMETERS

2. DIMENSIONS ARE IN

3. DRAWING NOT TO SCALE

SEE NOTE 4

4. RECOMMENDED MINIMUM PCB METAL SIZE

FOR EXPOSED PAD ATTACHMENT

6.40

(.252)

BSC

APPLICATIO S I FOR ATIO

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Figure 13. Kelvin Sensing of Charge CurrentFigure 12. High Speed Switching Path

4010 F12

BAT

HIGH

FREQUENCY

CIRCULATING

PATH

BAT

SWITCH NODE

SWITCHING GROUND

OUT

SENSE

4010 F13

DIRECTION OF CHARGING CURRENT

SENSE

BAT

LTC4010

4010p

LT/TP 0205 1K • PRINTED IN THE USA

PART NUMBER DESCRIPTION COMMENTS

LT®1510 Constant-Voltage/Constant-Current Battery Charger Up to 1.5A Charge Current for Li-Ion, NiCd and NiMH Batteries

LT1511 3A Constant-Voltage/Constant-Current Battery Charger High Efficiency, Minimum External Components to Fast Charge

Lithium, NiMH and NiCd Batteries

LT1513 SEPIC Constant- or Programmable-Current/Constant- Charger Input Voltage May be Higher, Equal to or Lower Than

Voltage Battery Charger Battery Voltage, 500kHz Switching Frequency

LTC1760 Smart Battery System Manager Autonomous Power Management and Battery Charging for Two

Smart Batteries, SMBus Rev 1.1 Compliant

LTC1960 Dual Battery Charger/Selector with SPI 11-Bit V-DAC, 0.8% Voltage Accuracy, 10-Bit I-DAC,

5% Current Accuracy

LTC4008 High Efficiency, Programmable Voltage/Current Battery Constant-Current/Constant-Voltage Switching Regulator, Resistor

Charger Voltage/Current Programming, AC Adapter Current Limit and

Thermistor Sensor and Indicator Outputs

LTC4011 High Efficiency Standalone Nickel Battery Charger Complete NiMH/NiCd Charger in a 20-Pin TSSOP Package,

PowerPathTM Contol, Constant-Current Switching Regulator

LTC4060 Standalone Linear NiMH/NiCd Fast Charger Complete NiMH/NiCd Charger in a Small Leaded or Leadless

16-Pin Package, No Sense Resistor or Blocking Diode Required

LTC4100 Smart Battery Charger Controller Level 2 Charger Operates with or without MCU Host,

SMBus Rev. 1.1 Compliant

LTC4150 Coulomb Counter/Battery Gas Gauge High Side Sense of Charge Quantity and Polarity in a 10-Pin MSOP

LTC4412 Low Loss PowerPath Controller Very Low Loss Replacement for Power Supply ORing Diodes

Using Minimal External Components

LTC4413 Dual, 2.6A Ideal Diode in 3mm × 3mm DFN 2.5V ≤ V

≤ 5.5V, Ideal Diode ORing or Load Sharing,

Low Reverse Leakage Current

PowerPath is a trademark of Linear Technology Corporation.

RELATED PARTS

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900

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FAX: (408) 434-0507

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