LINEAR TECHNOLOGY LTC4101 Technical data

FEATURES

■

Single Chip Smart Battery Charger Controller

■

100% Compliant (Rev. 1.1) SMBus Support Allows
for Operation with or without Host

■

Up to 4A Charging Current Capability

■

High Efficiency Synchronous Buck Charger

■

V

Optimized 3V to 5.5V

BAT

■

SMBus Accelerator Improves SMBus Timing

■

Hardware Interrupt and SMBAlert Response
Eliminate Interrupt Polling

■

0.5V Dropout Voltage; Maximum Duty Cycle > 98%

■

AC Adapter Current Limit Maximizes Charge Rate

■

±0.8% Voltage Accuracy; ±4% Current Accuracy

■

10-Bit DAC for Charge Current Programming

■

11-Bit DAC for Charger Voltage Programming

■

User-Selectable Overvoltage and Overcurrent Limits

■

High Noise Immunity SafetySignal Sensor

■

Available in a 24-Pin SSOP Package

U

APPLICATIO S

■

Portable Instruments and Computers

■

Data Storage Systems and Battery Backup Servers

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All
other trademarks are the property of their respective owners. Protected by U.S. Patents
including 6650174, 5723970.

LTC4101

Smart Battery

Charger Controller

U

DESCRIPTIO

The LTC®4101 Smart Battery Charger is a single chip
charging solution that dramatically simplifies construc­tion of an SBS compliant system. The LTC4101 imple­ments a Level 2 charger function whereby the charger can
be programmed by the battery or by the host. A SafetySignal
on the battery being charged is monitored for tempera­ture, connectivity and battery type information. The SMBus
interface remains alive when the AC power adapter is
removed and responds to all SMBus activity directed to
it, including SafetySignal status (via the ChargerStatus
command). The charger also provides an interrupt to the
host whenever a status change is detected (e.g., battery
removal, AC adapter connection).

Charging current and voltage are restricted to chemistry­specific limits for improved system safety and reliability.
Limits are programmable by two external resistors. Addi­tionally, the maximum average current from the AC adapter
is programmable to avoid overloading the adapter when
simultaneously supplying load current and charging
current. When supplying system load current, charging
current is automatically reduced to prevent adapter
overload.

TYPICAL APPLICATIO

DCIN

9V to 12V, 2A

3V

TO 5.5V

CHGEN

ACP

1.13k

54.9k

SMBALERT#

SMBCLK

SMBDAT

U

1.21k

LTC4101

DCIN

INFET

CLP

CLN

TGATE

BGATE

PGND

CSP

BAT

V

GND

0.1µF

SET

I

TH

5

4

24

23

1

3

2

21

22

18

19

12

6.04k

0.12µF

SafetySignal

10k

6.04k

17

11

6

10

7

9

8

15

16

13

14

20

0.068µF

V

DD

DCDIV

CHGEN

ACP

SMBALERT

SCL

SDA

THB

THA

I

LIM

V

LIM

I

DC

Figure 1. 1A Smart Battery Charger

0.1µF

5k

0.0015µF

0.05Ω

5µF

24µH

0.03µF

0.1µF

0.1Ω 1%

100Ω

V

BAT

< 5.5V
> 5.5V

5µF

PART

LTC4101
LTC4100

SMART BATTERY

SMBCLK

SMBDAT

SYSTEM LOAD

4101 F01a

4101f

1

LTC4101

WW

W

U

ABSOLUTE AXI U RATI GS

(Note 1)

Voltage from VDD to GND ................................ 7V/–0.3V

Voltage from CHGEN, DCDIV, SDA, SCL

and SMBALERT to GND .............................. 7V/–0.3V

Voltage from DCIN, CLP, CLN to GND ........... 32V/–0.3V

Voltage from CLP to CLN...................................... ±0.3V

PGND wrt. GND .................................................... ±0.3V

CSP, BAT to GND.............................................. 28V/–5V

Operating Ambient Temperature Range (Note 4)

........................................................... – 40°C to 85°C

Junction Temperature Range............... – 40°C to 125°C

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

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

UUW

PACKAGE/ORDER I FOR ATIO

TOP VIEW

1

TGATE

2

PGND

3

BGATE

4

INFET

5

DCIN

6

CHGEN

SMBALERT

7

8

SDA

9

SCL

10

ACP

11

DCDIV

12

GND

24-LEAD PLASTIC SSOP

T

= 125°C, θJA = 90°C/W

JMAX

G PACKAGE

ORDER PART NUMBER

LTC4101EG

CLP

24

CLN

23

BAT

22

CSP

21

I

20

DC

I

19

TH

V

18

SET

V

17

DD

THA

16

THB

15

V

14

LIM

I

13

LIM

Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF

Lead Free Part Marking: http://www.linear.com/leadfree/

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

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at T

The ● denotes the specifications which apply over the full operating

= 25°C. V

A

= 20V, VDD = 3.3V, V

DCIN

= 4V unless otherwise noted. (Note 4)

BAT

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

DCIN

DCIN Operating Range

DCIN Operating Current Charging, Sum of Currents on 3 5 mA

●

628V

DCIN, CLP and CLN

V

I

V

TOL

TOL

DD

Charge Voltage Accuracy (Note 2) –1.1 1.1 %

●

–1.3 1.3 %

Charge Current Accuracy (Note 3) V

VDD Operating Voltage 0V ≤ V

I

CSP

DAC

– V

Target = 102.3mV –2 6 %

BAT

= 0xFFFF

≤ 28V

DCIN

●

–3 7 %

●

3 5.5 V

Shutdown

Battery Leakage Current DCIN = 0V, V

UVLO Undervoltage Lockout Threshold DCIN Rising, V

VDD Power-Fail Part Held in Reset Until this VDD Present

DCIN Current in Shutdown V

= 0V 2 3 mA

CHGEN

CLP

BAT

= V

= 0V

CLN

= V

CSP

= V

BAT

●

●

4.2 4.7 5.5 V

●

15 35 µA

3V

Current Sense Amplifier, CA1

Input Bias Current into BAT Pin 11.66 µA

CMSL CA1/I1 Input Common Mode Low

CMSH CA1/I1 Input Common Mode High V

DCIN

≤ 28V

●

0V

●

V

-0.2 V

CLN

4101f

2

LTC4101

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at T

The ● denotes the specifications which apply over the full operating

= 25°C. V

A

= 20V, VDD = 3.3V, V

DCIN

= 4V unless otherwise noted. (Note 4)

BAT

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Current Comparators I

I

TREV

REV

Reverse Current Threshold (V

CSP-VBAT

)–30mV

Current Sense Amplifier, CA2

Transconductance 1 mmho

Source Current Measured at ITH, V

Sink Current Measured at ITH, V

= 1.4V –40 µA

ITH

= 1.4V 40 µA

ITH

Current Limit Amplifier

Transconductance 1.5 mmho

V

I

CLP

CLN

Current Limit Threshold

●

93 100 107 mV

CLN Input Bias Current 50 nA

Voltage Error Amplifier, EA

Transconductance 1 mmho

Sink Current Measured at I

OVSD Overvoltage Shutdown Threshold as a Percent

= 1.4V 36 µA

TH, VITH

●

102 107 110 %

of Programmed Charger Voltage

Input P-Channel FET Driver (INFET)

DCIN Detection Threshold (V

DCIN-VCLP

Forward Regulation Voltage (V

Reverse Voltage Turn-Off Voltage (V

INFET “ON” Clamping Voltage (V

INFET “OFF” Clamping Voltage (V

) DCIN Voltage Ramping Up

from V

CLP

DCIN-VCLP

)

DCIN-VCLP

DCIN-VINFET

DCIN-VINFET

)

)I

)I

= 1µA

INFET

= –25µA 0.25 V

INFET

-0.05V

●

0 0.17 0.25 V

●

●

–60 –25 mV

●

5 5.8 6.5 V

25 50 mV

Oscillator

f

f

DC

OSC

MIN

MAX

Regulator Switching Frequency 255 300 345 kHz
Regulator Switching Frequency in Drop Out Duty Cycle ≥ 98% 20 25 kHz

Regulator Maximum Duty Cycle V

CSP

= V

BAT

98 99 %

Gate Drivers (TGATE, BGATE)

V

High (V

TGATE

V

BGATE

V

TGATE

V

BGATE

CLP-VTGATE

High C

Low (V

CLP-VTGATE

Low I

)I

)C

= –1mA 50 mV

TGATE

= 3000pF 4.5 5.6 10 V

LOAD

= 3000pF 4.5 5.6 10 V

LOAD

= 1mA 50 mV

BGATE

TGATE Transition Time
TGTR TGATE Rise Time C
TGTF TGATE Fall Time C

= 3000pF, 10% to 90% 50 110 ns

LOAD

= 3000pF, 10% to 90% 50 100 ns

LOAD

BGATE Transition Time
BGTR BGATE Rise Time C
BGTF BGATE Fall Time C

V

at Shutdown (V

TGATE

V

at Shutdown I

BGATE

CLN-VTGATE

)I

= 3000pF, 10% to 90% 40 90 ns

LOAD

= 3000pF, 10% to 90% 40 80 ns

LOAD

= –1µA 100 mV

TGATE

= 1µA 100 mV

TGATE

4101f

3

LTC4101

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at T

The ● denotes the specifications which apply over the full operating

= 25°C. V

A

= 20V, VDD = 3.3V, V

DCIN

= 4V unless otherwise noted. (Note 4)

BAT

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

AC Present Comparator

V

ACP

DCDIV Threshold V

Rising from 1V to 1.4V

DCDIV

●

1.14 1.20 1.26 V

DCDIV Hysteresis 25 mV

DCDIV Input Bias Current V

ACP V

OH

ACP V

OL

DCDIV to ACP Delay V

= 1.2V –1 1 µA

DCDIV

I

= –2mA 2 V

ACP

I

= 1mA 0.5 V

ACP

= 1.3V 10 µs

DCDIV

SafetySignal Decoder

SafetySignal Trip (RES_COLD/RES_OR) R

SafetySignal Trip (RES_IDEAL/RES_COLD) R

SafetySignal Trip (RES_HOT/RES_IDEAL) R

SafetySignal Trip (RES_UR/RES_HOT) R

= 1130Ω ±1%, C

THA

= 54.9Ω ±1%

R

THB

= 1130Ω ±1%, C

THA

= 54.9Ω ±1%

R

THB

= 1130Ω ±1%, C

THA

= 54.9Ω ±1%

R

THB

= 1130Ω ±1%, C

THA

R

= 54.9Ω ±1%

THB

= 1nF (Note 6)

TH

= 1nF (Note 6)

TH

= 1nF (Note 6)

TH

= 1nF (Note 6)

TH

●

95 100 105 kΩ

●

28.5 30 31.5 kΩ

●

2.85 3 3.15 kΩ

●

425 500 575 Ω

Time Between SafetySignal Measurements DCDIV = 1.3V 32 ms

DCDIV = 1V 250 ms

DACs

Charging Current Resolution Guaranteed Monotonic Above I

Charging Current Granularity R

Wake-Up Charging Current (I

) All Values of R

WAKE-UP

Charging Current Limit R

= 0 1 mA

ILIM

= 10k ±1% 2 mA

R

ILIM

= 33k ±1% 4 mA

R

ILIM

R

= Open (or Short to VDD)4mA

ILIM

All Values of R

ILIM =

ILIM
VLIM

0 (0-1A) 97.3 107.3 mV

/16 10 Bits

MAX

80 (Note 5) mA

CSP – BAT Charging Current = 0x03FF (0x0400 Note 7)

R

10k ±1% (0-2A) 97.3 107.3 mV

ILIM =

Charging Current = 0x07FE (0x0800 Note 7)

R

33k ±1% (0-3A) 72.3 82.3 mV

ILIM =

Charging Current = 0x0BFC (0x0C00 Note 7)

R

0pen (or Short to VDD) (0-4A)

ILIM =

●

97.3 107.3 mV

Charging Current = 0x0FFC (0x1000 Note 7)

Charging Voltage Resolution Guaranteed Monotonic (2.9V ≤ V

5.6V) 11 Bits

BAT ≤

Charging Voltage Granularity 16 mV

Charging Voltage Limit R

= 0 4.206 4.240 4.274 V

VLIM

Charging Voltage = 0x1090 (Note 7)

R

= 10k ±1% 4.270 4.304 4.338 V

VLIM

Charging Voltage = 0x10D0 (Note 7)

R

= 33k ±1% 4.397 4.432 4.467 V

VLIM

Charging Voltage = 0x1150 (Note 7)

R

= 100k ±1% 4.476 4.512 4.548 V

VLIM

Charging Voltage = 0x11A0 (Note 7)

R

= 0pen (or Short to VDD) 5.460 5.504 5.548 V

VLIM

Charging Voltage = 0x1580 (Note 7)

4101f

4

LTC4101

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at T

The ● denotes the specifications which apply over the full operating

= 25°C. V

A

= 20V, VDD = 3.3V, V

DCIN

= 4V unless otherwise noted. (Note 4)

BAT

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Logic Levels

V

V

V

I

IL

I

IH

V

I

LEAK

V

V

V

IL

IH

OL

OL

OL

IL

IH

SCL/SDA Input Low Voltage VDD = 3V and VDD = 5.5V

SCL/SDA Input High Voltage VDD = 3V and VDD = 5.5V

SDA Output Low Voltage I

SCL/SDA Input Current V

SCL/SDA Input Current V

SMBALERT Output Low Voltage I

SMBALERT Output Pull-Up Current V

SDA/SCL/SMBALERT Power Down Leakage V

PULL-UP

, V

SDA

, V

SDA

PULL-UP

SMBALERT

, V

SDA

= 350µA

= V

SCL

= V

SCL

= 500µA

= V

, V

SCL

IL

IH

OL

SMBALERT

= 5.5V, VDD = OV

CHGEN Output Low Voltage IOL = 100µA

CHGEN Output Pull-Up Current V

CHGEN

= V

OL

CHGEN Input Low Voltage

CHGEN Input High Voltage VDD = 3V

= 5.5V 3.9 V

V

DD

●

●

2.1 V

●

0.8 V

0.4 V

–1 1 µA

–1 1 µA

●

0.4 V

–17.5 –10 –3.5 µA

●

–2 2 µA

●

0.5 V

–17.5 –10 –3.5 µA

●

●

2.5 V

0.9 V

Power-On Reset Duration VDD Ramp from 0V to >3V in <5µs 100 µs

SMBus Timing (Refer to System Management Bus Specification, Revision 1.1, Section 2.1 for Timing Diagrams)

t

HIGH

t

LOW

t

R

t

F

t

SU:STA

t

HD:STA

t

HD:DAT

SCL Serial Clock High Period I

SCL Serial Clock Low Period I

SDA/SCL Rise Time C

SDA/SCL Fall Time C

= 350µA, C

PULL-UP

V

= 3V and VDD = 5.5V

DD

= 350µA, C

PULL-UP

V

= 3V and VDD = 5.5V

DD

= 250pF, RPU = 9.31k, VDD = 3V

LOAD

= 5.5V

and V

DD

= 250pF, RPU = 9.31k, VDD = 3V

LOAD

= 5.5V

and V

DD

LOAD

LOAD

Start Condition Setup Time VDD = 3V and VDD = 5.5V

Start Condition Hold Time VDD = 3V and VDD = 5.5V

SDA to SCL Falling-Edge Hold Time, VDD = 3V and VDD = 5.5V

= 250pF, RPU = 9.31k,

= 250pF, RPU = 9.31k,

●

4 µs

●

4.7 15000 µs

●

●

●

4.7 µs

●

4 µs

●

300 ns

1000 ns

300 ns

Slave Clocking in Data

t

TIMEOUT

Time Between Receiving Valid VDD = 3V and VDD = 5.5V

●

140 175 210 sec
ChargingCurrent() and
ChargingVoltage() Commands

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
reliabilty and lifetime.

Note 2: See Test Circuit.
Note 3: Does not include tolerance of current sense resistor.
Note 4: The LTC4101E is guaranteed to meet performance specifications

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

temperature range are assured by design, characterization and correlation
with statistical process controls.

Note 5: Current accuracy dependent upon circuit compensation and sense
resistor.

Note 6: C

is defined as the sum of capacitance on THA, THB and

TH

SafetySignal.
Note 7: The corresponding overrange bit will be set when a HEX value

greater than or equal to this value is used.

4101f

5

LTC4101

UW

TYPICAL PERFOR A CE CHARACTERISTICS

INFET Response Time to
Reverse Current Output Voltage vs Output Current PWM Frequency vs Duty Cycle

0

–0.5

–1.0

–1.5

–2.0

–2.5

–3.0

–3.5

–4.0

OUTPUT VOLTAGE ERROR (%)

V

= 20V

DCIN

= 4.176V

V

PROG

–4.5

–5.0

= 4V

I

PROG

0 0.5 1.0 2.0 3.0 4.01.5 2.5 3.5 4.5

OUTPUT CURRENT (A)

= 0

V

gs

V

= 0V

s

Id (REVERSE) OF
PFET (5A/DIV)

I

= 0A

d

TEST PERFORMED ON DEMOBOARD

= 15V

V

IN

DC

CHARGER = ON

= <10mA

I

CHARGE

Vgs OF PFET (2V/DIV)

Vs OF PFET (5V/DIV)

1.25µs/DIV

V

= 4.2V

CHARGE

INFET = 1/2 Si4925DY

4101 G01

TA = 25°C unless otherwise noted.

350

300

250

200

150

PROGRAMMED CURRENT = 10%

DCIN = 9V
DCIN = 12V

0

0 0.1 0.2 0.4 0.6 0.90.80.3 0.5 0.7 1.0

DCIN = 24V

DUTY CYCLE (V

4101 G02

100

PWM FREQUENCY (kHz)

50

OUT/VIN

)

4101 G03

Disconnect/Reconnect Battery
(Load Dump)

3A STEP

DISCONNECT

= 4.2V

FLOAT

1A STEP

V

FLOAT

1V/(DIV)

LOAD

STATE

LOAD CURRENT = 1A, 2A, 3A
DCIN = 12V
V

SMBus Accelerator Operation

VDD = 5V
C

BUS

5V

LTC4101

0V

1A STEP

3A STEP

RECONNECT

= 200pF

R

PULLUP

1µs/DIV

4101 G04

= 15k

Battery Leakage Current vs
Battery Voltage

40

VDCIN = 0V

35

30

25

20

15

10

BATTERY LEAKAGE CURRENT (µA)

5

0

0 5 10 15 20 25 30

4101 G09

BATTERY VOLTAGE (V)

Efficiency at V

100

96

92

88

84

80

POWER EFFICIENCY (%)

76

72

4101 G05

Low Current Operation

0.6
VDD = 5V

= 4V

V

BAT

0.5

0.4

(A)

0.3

CHARGE

I

0.2

0.1

= 20V

V

DCIN

= 4.208V

V

PROG

NO LOW

CURRENT

MODE

0

0.10

0.05

0

= 4.208V

PROG

VIN = 8V

VIN = 20V

0.50.0 1.51.0 2.0 2.5 3.53.0

I

PROGRAMMED
CURRENT

LOW
CURRENT
MODE

(A)

PROG

I

OUT

(A)

0.400.15 0.20 0.25 0.30 0.35

4101 G10

4101 G07

4101f

6

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LTC4101

TA = 25°C unless otherwise noted.

Charging Current Error

200

VDD = 5V

100

0

–100

OUTPUT CURRENT ERROR (mA)

–200

0

U

1
CHARGING CURRENT (A)

UU

V

= 20V

DCIN

V

= 9V

DCIN

2

43

4101 G11

PI FU CTIO S

TGATE (Pin 1): Drives the Top External P-MOSFET of the
Battery Charger Buck Converter.

PGND (Pin 2): High Current Ground Return for BGATE
Driver.

BGATE (Pin 3): Drives the Bottom External N-MOSFET of
the Battery Charger Buck Converter.

INFET (Pin 4): Drives the Gate of the External Input
P-MOSFET.

DCIN (Pin 5): External DC Power Source Input. Bypass to
ground with a 0.1µF capacitor.

CHGEN (Pin 6): Digital Bidirectional Pin to Enable Charger
Function. This pin is connected as a wired AND bus.

The following events will cause the POWER_FAIL bit in
the ChargerStatus register to become set:

1. An external device pulling the CHGEN signal to within

0.9V to GND;

2. The AC adapter voltage is not above the battery
voltage.

Transfer Function of Charger

50

VDD = 5V

= 0.120A

I

BAT

V

= 9V

0

–50

–100

OUTPUT VOLTAGE ERROR (V)

–150

0

CHARGING VOLTAGE (V)

V

DCIN

V

DCIN

= 20V

= 28V

DCIN

45312 6

4101 G12

any action on its part is required. This signal can be
connected to the optional SMBALERT line of the SMBus.
Open drain with weak current source pull-up to V

DD

(with

Schottky to allow it to be pulled to 5V externally).

SDA (Pin 8): SMBus Data Signal from Main (host-con­trolled) SMBus. External pull-up resistor is required.

SCL (Pin 9): SMBus Clock Signal from Main (host-con­trolled) SMBus. External pull-up resistor is required.

ACP (Pin 10): This Output Indicates the Value of the DCDIV
Comparator. It can be used to indicate whether AC is
present or not.

DCDIV (Pin 11): Supply Divider Input. This is a high
impedance comparator input with a 1.2V threshold (rising
edge) and hysteresis.

GND (Pin 12): Ground for Digital and Analog Circuitry.

I

(Pin 13): An external resistor is connected between

LIM

this pin and GND. The value of the external resistor
programs the range and resolution of the programmed
charger current.

SMBALERT (Pin 7): Active Low Interrupt Output to Host
(referred to as the SMBALERT signal in the SMBus Revi­sion 1.1 specification). Signals host that there has been a
change of status in the charger registers and that the host
should read the LTC4101 status registers to determine if

V

(Pin 14): An external resistor is connected between

LIM

this pin and GND. The value of the external resistor
programs the range and resolution of the charging
voltage.

4101f

7

LTC4101

U

UU

PI FU CTIO S

THB (Pin 15): SafetySignal Force/Sense Pin to Smart
Battery. See description of operation for more detail. The
maximum allowed combined capacitance on THA, THB
and SafetySignal is 1nF (see Figure 4). A series resistor

54.9k needs to be connected between this pin and the
battery’s SafetySignal for this circuit to work correctly.

THA (Pin 16): SafetySignal Force/Sense Pin to Smart
Battery. See description of operation for more detail. The
maximum allowed combined capacitance on THA, THB
and SafetySignal is 1nF (see Figure 4). A series resistor
1130Ω needs to be connected between this pin and the
battery’s SafetySignal for this circuit to work correctly.

V

(Pin 17): Power Supply Input for the LTC4101 Digital

DD

Circuitry. Bypass this pin with 0.1µF. Typically between

3.3V and 5V

V

(Pin 18): Tap Point of the Programmable Resistor

SET

Divider, which Provides Battery Voltage Feedback to the
Charger.

DC

.

ITH (Pin 19): Control Signal of the Inner Loop of the
Current Mode PWM. Higher I
charging current in normal operation. A 0.0015µF capaci­tor to GND filters out PWM ripple. Typical full-scale output
current is 40µA. Nominal voltage range for this pin is 0V
to 3V.

I

(Pin 20): Bypass to GND with a 0.068µF Capacitor.

DC

CSP (Pin 21): Current Amplifier CA1 Input. This pin and

the BAT pin measure the voltage across the sense resistor,
R
quired for both peak and average current mode operation.

BAT (Pin 22): Battery Sense Input and the Negative
Reference for the Current Sense Resistor. A bypass ca­pacitor of at least 10µF is required.

CLN (Pin 23): Negative Input to the Input Current Limiting
Circuit Block. If no current limit function is desired, con­nect this pin to CLP. The threshold is set at 100mV below
the voltage at the CLP pin. When used to limit supply
current, a filter is needed to filter out the switching noise.

, to provide the instantaneous current signals re-

SENSE

corresponds to higher

TH

CLP (Pin 24): Positive Input to the Input Current Limiting
Circuit Block. This pin also serves as a power supply for
the IC.

8

4101f

BLOCK DIAGRA

LTC4101

W

V

BAT

SYSTEM
LOAD

L1

CSP

D1

R1

R

CL

Q1

V

IN

TO HOST AND BATTERY

1.13k

54.9k

R4

100Ω

C5, 0.1µF

C9

C1, 0.1µF

10k

0.03µF

Q2

Q3

C4

V

GND

20µF

TGATE

BGATE

PGND

CLN

CLP

DCIN

INFET

CHGEN

SMBALERT

SDA

SCL

THA

THB

SET

V

20µF

R

ILIM

BAT

C7

0.0015µF

V

IN

–

+

+
–

–

+

10-BIT

I

DAC

3k

11.67µA

3k

9k

17mV

1.19V

1.2V

CA1

BUFFERED

÷ 5

I

CMP

I

REV

gm = 1m

–

+

–

+

I

TH

CA2

Ω

LIMIT

DECODER

18

11-BIT

V

10µA

t

PWM

LOGIC

DAC

1.28V

ON

1.19V

100mV

V

DD

SMBus

INTERFACE

AND CONTROL

THERMISTER

INTERFACE

–

EA

+

Q

+

CL1

–

0V

gm = 1m

S
R

gm = 1.5m

Ω

Ω

CLP

12

1

3

2

23

24

5

4

6

7

8

9

16

15

CLP

DCIN

OSCILLATOR

WATCHDOG

DETECT

5.8V

22

R

21

20

19

10

11

17

13

14

BAT

SENSE

CSP

CSP

I

DC

I

TH

C6, 0.12µF

ACP
DCDIV

R11

V

TO SMBUS

DD

POWER SUPPLY

I

LIM

V

LIM

R

VLIM

C8

0.068µF

R5, 6.04k

R10

Figure 2.

4101f

9