LINEAR TECHNOLOGY LTC1960 Technical data

FEATURES

LTC1960

Dual Battery Charger/

Selector with SPI Interface

U

DESCRIPTIO

■

Complete Dual-Battery Charger/Selector System

■

Serial SPI Interface Allows External µC Control and Monitoring

■

Simultaneous Dual-Battery Discharge Extends Run Time by Typically 10%

■

Simultaneous Dual-Battery Charging Reduces Charging Time by Up to 50%

■

Automatic PowerPathTM Switching in <10µs Prevents Power Interruption

■

Circuit Breaker Protects Against Overcurrent Faults

■

5% Accurate Adapter Current Limit Maximizes Charging Rate*

■

95% Efficient Synchronous Buck Charger

■

Charger Has Low 0.5V Dropout Voltage

■

No Audible Noise Generation, Even with Ceramic Capacitors

■

11-Bit VDAC Delivers 0.8% Voltage Accuracy

■

10-Bit IDAC Delivers 5% Current Accuracy

■

VIN Up to 32V; V

■

Available in 5mm × 7mm 38-Pin QFN and 36-Pin

Up to 28V

BATT

Narrow SSOP Packages

U

APPLICATIO S

■

Portable Computers

■

Portable Instruments

The LTC®1960 is a highly-integrated battery charger and selector intended for portable products using dual smart batteries. A serial SPI interface allows an external microcontroller to control and monitor status of both batteries.

A proprietary PowerPath architecture supports simultaneous charging or discharging of both batteries. Typical battery run times are extended by 10%, while charging times are reduced by up to 50%. The LTC1960 automatically switches between power sources in less than 10µs to prevent power interruption upon battery or wall adapter removal.

The synchronous buck battery charger delivers 95% efficiency with only 0.5V dropout voltage, and prevents audible noise in all operating modes. Patented* input current limiting with 5% accuracy charges batteries in the shortest possible time without overloading the wall adapter.

The LTC1960’s 5mm × 7mm 38-pin QFN and 36-pin narrow SSOP packages allow implementation of a complete SBS-compliant dual battery system while consuming minimum PCB area.

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents, including 5481178, 5723970, 6304066, 6580258.

TYPICAL APPLICATIO

LTC1960 Dual Battery/Selector System Architecture

DC

IN

BAT2 BAT1

U

SYSTEM POWER

LTC1960 MICROCONTROLLER

4

SPI

SMBus

1960 TA01

Dual vs Sequential Charging

3500 3000 2500 2000 1500 1000

500

0 3500 3000 2500 2000

BATTERY CURRENT (mA)

1500 1000

500

0

BATTERY TYPE: 10.8V Li-Ion (MOLTECH NI2020) REQUESTED CURRENT = 3A REQUESTED VOLTAGE = 12.3V MAX CHARGER CURRENT = 4.1A

BAT1

CURRENT

50

BAT1 CURRENT

100 150 200 250 300

TIME (MINUTES)

BAT2 CURRENT

MINUTES

SEQUENTIAL

DUAL

100

1960 G10

1960fa

1

LTC1960

WW

W

ABSOLUTE AXI U RATI GS

Voltage from DCIN, SCP, SCN, CLP, V

PLUS

U

(Note 1)

,

SW to GND ................................................32V to – 0.3V

Voltage from SCH1, SCH2 to GND.............28V to –0.3V

Voltage from BOOST to GND .....................41V to –0.3V

PGND with Respect to GND .................................. ±0.3V

CSP, CSN, BAT1, BAT2 to GND ....................28V to – 5V

LOPWR, DCDIV to GND .............................10V to –0.3V

UUW

PACKAGE/ORDER I FOR ATIO

TOP VIEW

LOPWR

GB2I

GB2O

GB1I

GB1O

GDCI

GDCO

38 37 36 35 34 33 32

1V

SET

I

2

TH

I

3

SET

GND

4

DCDIV

5

SSB

6

SCK

7

MISO

8

MOSI

9

GND

10

CSN

11

CSP

12

13 14 15 16

CLP

38-LEAD (5mm × 7mm) PLASTIC QFN

T

THE EXPOSED PAD (PIN 39) IS GND. MUST BE SOLDERED TO THE PCB.

JMAX

39

17 18 19

CC

V

PGND

BGATE

COMP1

UHF PACKAGE

= 125°C, θJA = 34°C/W

UHF PART MARKING

LTC1960CUHF

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.

DCIN

SW

31

SCP

SCN

30

BAT1

29

BAT2

28

V

27

GND

26

SCH2

25

GCH2

24

GCH1

23

22

SCH1

21

TGATE

20

BOOST

1960

PLUS

SSB, SCK, MOSI, MISO to GND................... 7V to –0.3V

COMP1 to GND ............................................ 5V to –0.3V

Operating Ambient Temperature

Range (Note 7) ........................................0°C to 70°C

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

Storage Temperature ............................ –65°C to 185°C

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

TOP VIEW

V

PLUS

BAT2

BAT1

SCN

SCP

GDCO

GDCI

GB1O

GB1I

GB2O

GB2I

LOPWR

V

SET

I

SET

GND

DCDIV

SSB

1

2

3

4

5

6

7

8

9

10

11

12

13

14

TH

15

16

17

18

G PACKAGE

36-LEAD PLASTIC SSOP

T

= 125°C, θJA = 95°C/ W

JMAX

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

20

19

SCH2

GCH2

GCH1

SCH1

TGATE

BOOST

SW

DCIN

V

CC

BGATE

PGND

COMP1

CLP

CSP

CSN

MOSI

MISO

SCK

ORDER PART NUMBER

LTC1960CG

ELECTRICAL CHARACTERISTICS

temperature range (Note 7), otherwise specifications are at T

The ● denotes specifications which apply over the full operating

= 25°C.

V

A

DCIN

= 20V, V

BAT1

= 12V, V

= 12V unless otherwise noted.

BAT2

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply and Reference

DCIN Operating Range DCIN Selected 6 28 V

I

CH

DCIN Operating Current Not Charging (DCIN Selected) 1 1.5 mA

Charging (DCIN Selected) 1.3 2 mA

1960fa

2

LTC1960

ELECTRICAL CHARACTERISTICS

temperature range (Note 7), otherwise specifications are at T

The ● denotes specifications which apply over the full operating

= 25°C.

V

A

DCIN

= 20V, V

BAT1

= 12V, V

= 12V unless otherwise noted.

BAT2

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply and Reference

Battery Operating Voltage Range Battery Selected, PowerPath Function (Note 2) 6 28 V

Battery Drain Current Battery Selected, Not Charging, V

V

Diodes Forward Voltage:

PLUS

V V V V

FDC FB1 FB2 FSCN

DCIN to V BAT1 to V BAT2 to V SCN to V

PLUS PLUS PLUS

PLUS

UVLO Undervoltage Lockout Threshold V

UVHYS UV Lockout Hysteresis V

V

VCC

V

LDR

VCC Regulator Output Voltage 5 5.2 5.4 V

VCC Load Regulation I

I

= 10mA 0.8 V

VCC

I

= 0mA 0.7 V

VCC

I

= 0mA 0.7 V

VCC

I

= 0mA 0.7 V

VCC

Ramping Down, Measured at V

PLUS

Rising, Measured at V

PLUS

= 0mA to 10mA 0.2 1 %

VCC

= 0V 175 µA

DCIN

to GND

PLUS

to GND 60 mV

PLUS

●

3 3.5 3.9 V

Switching Regulator

V

I

f

TOL

0SC

DO

Overall Voltage Accuracy 5V ≤ V

Overall Current Accuracy IDAC Value = 3FF

V

< 25V, (Note 3) –0.8 0.8 %

CSP

, V

OUT

CSN

HEX

= 12V

●

–1 1 %

–5 5 %

●

–6 6 %

Regulator Switching Frequency 255 300 345 kHz Regulator Switching Frequency in Low Duty Cycle ≥99% 20 25 kHz

Dropout Mode

DC

I

MAX

I

SNS

MAX

Regulator Maximum Duty Cycle 99 99.5 %

Maximum Current Sense Threshold V

CA1 Input Bias Current V

= 2.2V 140 155 190 mV

ITH

= V

CSP

> 5V 150 µA

CSN

CMSL CA1/I1 Input Common Mode Low 0 V

CMSH CA1/I1 Input Common Mode High V

V

CL1

CL1 Turn-On Threshold 95 100 105 mV

–0.2 V

DCIN

TGATE Transition Time: TG t TG t

r f

TGATE Rise Time C TGATE Fall Time C

= 3300pF, 10% to 90% 50 90 ns

LOAD

= 3300pF, 10% to 90% 50 90 ns

LOAD

BGATE Transition Time: BG t BG t

r f

BGATE Rise Time C BGATE Fall Time C

= 3300pF, 10% to 90% 50 90 ns

LOAD

= 3300pF, 10% to 90% 40 80 ns

LOAD

Trip Points

V

I

V

BVT

TR

THYS

TSC

FTO

OVSD

DCDIV/LOPWR Threshold V

DCDIV/LOPWR Hysteresis Voltage V

DCDIV/LOPWR Input Bias Current V

Short-Circuit Comparator Threshold V

Fast Power Path Turn-Off Threshold V

Overvoltage Shutdown Threshold as a V

or V

DCDIV

or V

DCDIV

or V

DCDIV

– V

SCP

SCN

Rising from V

DCDIV

Rising from 0.8V until TGATE and BGATE 107 %

SET

Falling

LOPWR

Rising 30 mV

LOPWR

= 1.19V 20 200 nA

LOPWR

, V

≥ 5V

CC

●

1.166 1.19 1.215 V

●

90 100 115 mV

6 7 7.9 V

Percent of Programmed Charger Voltage Stop Switching

DACs

I

RES

IDAC Resolution Guaranteed Monotonic Above I

/16 10 bits

MAX

IDAC Pulse Period: t

IP

t

ILOW

Normal Mode 61015 µs Low Current Mode 50 ms

1960fa

3

LTC1960

ELECTRICAL CHARACTERISTICS

temperature range (Note 7), otherwise specifications are at T

The ● denotes specifications which apply over the full operating

= 25°C.

V

A

DCIN

= 20V, V

BAT1

= 12V, V

= 12V unless otherwise noted.

BAT2

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

DACs

V

t

RES

STEP

OFF

VP

VDAC Resolution Guaranteed Monotonic (5V < V

< 25V) 11 bits

BAT

VDAC Granularity 16 mV

VDAC Offset (Note 6) 0.8 V

VDAC Pulse Period 7 11 16.5 µs

Charge Mux Switches

t

ONC

t

OFFC

V

CON

V

COFF

V

TOC

V

FC

I

OC(SRC)

I

OC(SNK)

V

CHMIN

GCH1/GCH2 Tur-On Time V

GCH1/GCH2 Turn-Off Time V

CH Gate Clamp Voltage I

GCH1 V GCH2 V

CH Gate Off Voltage I

GCH1 V GCH2 V

CH Switch Reverse Turn-Off Voltage V

CH Switch Forward Regulation Voltage V

GCH1/GCH2 Active Regulation: V

GCHX

V

CSN

LOAD

CSN

BATX

GCHX

– V

< V

BATX

= 1µA

GCH1 GCH2

=10µA

GCH1 GCH2

– V

BATX,

– V

> 3V, V

SCHX

< 1V, from Time of 3 7 µs

SCHX

– 30mV, V

– V

SCH1

– V

SCH2

– V

SCH1

– V

SCH2

5V ≤ V 5V ≤ V

CSN,

= 1.5V

SCHX

BATX

= TBD, C

SCHX

≤ 28V ≤ 28V

= 3nF 5 10 ms

LOAD

= 3nF

LOAD

5 5.8 7 V 5 5.8 7 V

–0.8 –0.4 0 V –0.8 –0.4 0 V

●

52040 mV

●

15 35 60 mV

Max Source Current –2 µA Max Sink Current 2 µA

BATX Voltage Below Which 3.5 4.7 V

Charging is Inhibited (Does Not Apply

to Low Current Mode)

PowerPath Switches

t

DLY

t

PPB

t

ONPO

Blanking Period after UVLO Trip Switches Held Off 250 ms

Blanking Period after LOPWR Trip Switches in 3-Diode Mode 1 sec

GB1O/GB2O/GDCO Turn-On Time VGS < –3V, from Time of Battery/DC

●

510 µs

Removal, or LOPWR Indication

t

OFFPO

GB1O/GB2O/GDCO Turn-Off Time VGS > –1V, from Time of Battery/DC

●

37 µs

Removal, or LOPWR Indication

V

PONO

V

POFFO

V

TOP

V

FP

Output Gate Clamp Voltage I

LOAD

GB1O Highest (V GB2O Highest (V GDCO Highest (V

Output Gate Off Voltage I

LOAD

GB1O Highest (V GB2O Highest (V GDCO Highest (V

PowerPath Switch Reverse V

SCP

– V

Turn-Off Voltage 6V ≤ V

PowerPath Switch Forward V

BATX

Regulation Voltage 6V ≤ V

= 1µA

= –25µA

BATX

≤ 28V

SCP

– V

SCP

≤ 28V

SCP

BAT1 BAT2 DCIN

or V

or V or V

or V

or V or V or V

SCP

DCIN

SCP SCP SCP

– V

) – V ) – V ) – V

DCIN

SCP

GB1O GB2O GDCO

4.75 6.25 7 V

0.18 0.25 V

●

52060 mV

●

02550 mV

GDCI/GB1I/GB2I Active Regulation (Note 4) I

OP(SRC)

I

OP(SNK)

Source Current –4 µA Sink Current 75 µA

4

1960fa

LTC1960

ELECTRICAL CHARACTERISTICS

temperature range (Note 7), otherwise specifications are at T

The ● denotes specifications which apply over the full operating

= 25°C.

V

A

DCIN

= 20V, V

BAT1

= 12V, V

= 12V unless otherwise noted.

BAT2

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

t

ONPI

t

OFFPI

V

PONI

V

POFFI

Gate B1I/B2I/DCI Turn-On Time VGS < –3V, C

Gate B1I/B2I/DCI Turn-Off Time VGS > –1V, C

Input Gate Clamp Voltage I

GB1I Highest (V GB2I Highest (V GDCI Highest (V

Input Gate Off Voltage I

GB1I Highest (V GB2I Highest (V GDCI Highest (V

LOAD

= 1µA

BAT1 BAT2 DCIN

= –25µA

BAT1 BAT2 DCIN

= 3nF (Note 5) 300 µs

LOAD

= 3nF (Note 5) 10 µs

LOAD

or V or V

or V

or V or V

or V

SCP SCP SCP

) – V ) – V ) – V

GB1I GB2I GDCI

4.75 6.7 7.5 V

0.18 0.25 V

Logic I/O

IIH/I

V

IL

V

IH

V

OL

I

OFF

IL

SSB/SCK/MOSI Input High/Low Current

SSB/MOSI/SCK Input Low Voltage

SSB/MOSI/SCK Input High Voltage

MISO Output Low Voltage IOL = 1.3mA

MISO Output Off-State Leakage Current V

MISO

= 5V

●

–1 1 µA

●

2V

●

0.8 V

0.4 V

2 µA

SPI Timing (See Timing Diagram)

T

WD

t

SSH

t

CYC

t

SH

t

SL

t

LD

t

LG

t

su

t

H

t

A

t

dis

t

V

t

HO

t

Ir

t

If

t

Of

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.

Note 2. Battery voltage must be adequate to drive gates of PowerPath P-channel FET switches. This does not affect charging voltage of the battery, which can be zero volts.

Note 3. See Test Circuit. Note 4. DCIN, BAT1, BAT2 are held at 12V and GDCI, GB1I, GB2I are

Watch Dog Timer

●

1.2 2.5 4.5 sec

SSB High Time 680 ns

SCK Period C

LOAD

= 200pF R

= 4.7k on MISO

PULLUP

●

2 µs

SCK High Time 680 ns

SCK Low Time 680 ns

Enable Lead Time 200 ns

Enable Lag Time 200 ns

Input Data Set-Up Time

Input Data Hold Time

Access Time (From Hi-Z to Data Active on MISO)

Disable Time (Hold Time to Hi-Z State on MISO)

Output Data Valid CL = 200pF, R

Output Data Hold

= 4.7k on MISO

PULLUP

●

100 ns

●

100 ns

●

0ns

125 ns

580 ns

SCK/MOSI/SSB Rise Time 0.8V to 2V 250 ns

SCK/MOSI/SSB Fall Time 2V to 0.8V 250 ns

MISO Fall Time 2V to 0.4V, CL = 200 pF

●

400 ns

GB1I and GB2I. SCP is set at 11.9V to measure sink current at GDCI, GB1I and GB2I.

Note 5. Extrapolated from testing with C

= 50pF.

L

Note 6. VDAC offset is equal to the reference voltage, since

= V

V

OUT

(16mV • VDAC

REF

(VALUE)

/2047 + 1).

Note 7. The LTC1960C is guaranteed to meet specified performance from 0°C to 70°C and is designed, characterized and expected to meet specified performance at –40°C and 85°C, but is not tested at these extended temperature limits.

forced to 10.5V. SCP is set at 12.0V to measure source current at GDCI,

1960fa

5

LTC1960

TIME (ms)

–4 –2

BAT1 VOLTAGE (V)

14

12

10

8

6

4

2

0

1960 G05

42

10 12 14 16

0

68

VIN = 20V VDAC = 12.29V IDAC = 3000mA LOAD CURRENT = 1A T

A

= 25°C

BAT1 OUTPUT

LOAD CONNECTED

LOAD

DISCONNECTED

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Battery Drain Current (BAT1 Selected)

250

TA = 25°C

240

230

220

210

200

190

180

BAT1 CURRENT (µA)

170

160

150

6

12

Charger Efficiency

100

90

80

70

60

50

40

EFFICIENCY (%)

30

20

10

0

0.025

0

18

BAT1 VOLTAGE (V)

0.50

0.10 I

(A)

OUT

Power Path Autonomous

Power Path Switching

16

C

= 20µF

LOAD

15

= 0.8A

I

LOAD

= 25°C

T

A

14

13

12

11

10

LOAD VOLTAGE (V)

9

8

7

24

30

1960 G01

6

–50 –40 –30

–20

–10

TIME (µs)

LOPWR THRESHOLD

10 20 30 40 50

0

1960 G02

Charger Start-Up

12

10

8

6

4

CHARGER OUTPUT (V)

2

2.5 4.0

1960 G14

0 –0.05

0 0.10

0.05

0.30

0.20 0.40

0.25

0.15

TIME (SEC)

0.35

1960 G04

Switching

16

15

14

13

12

11

10

LOAD VOLTAGE (V)

9

8

7

6

BAT1 REMOVED

NOTE: LIGHT LOAD TO EXAGGERATE SWITCHING EVENT

–1

0

1

Charger Load Dump

23

TIME (SEC)

4

5

1960 G03

6

Charger Load Regulation

12.4

12.3

12.2

12.1

12.0

11.9

BAT1 VOLTAGE (V)

11.8

11.7

11.6

VIN = 20V VDAC = 12.288V IDAC = 4000mA

= 25°C

T

A

1000 2000 3000

0

CHARGE CURRENT (mA)

4000

1960 G06

Charging Current Accuracy

120

V

= 20V

DCIN

= 12V

V

BAT1

100

OUTPUT CURRENT ERROR (mA)

–20

–40

80

60

40

20

0

0 200

R

SNS

= 25°C

T

A

= 0.025Ω

400 800600

IDAC VALUE

1000

1200

1960 G07

IDAC Low Current Mode vs Normal Mode

500

VIN = 20V

450

400

350

300

250

200

150

CHARGING CURRENT (mA)

100

50

= 12V

V

BAT1

= 0.025Ω

R

SNS

= 25°C

T

A

LOW CURRENT

MODE

0

160

80

PROGRAMMED CURRENT (mA)

240

NORMAL MODE

320

400

480

560

1960 G08

1960fa

UW

BAT2

VOLTAGE

BAT2

CURRENT

BAT1 CURRENT

BAT1 VOLTAGE

BAT1 INITIAL CAPACITY = 0% BAT2 INITIAL CAPACITY = 90% PROGRAMMED CHARGER CURRENT = 3A PROGRAMMED CHARGER VOLTAGE = 16.8V

TIME (MINUTES)

0

BATTERY VOLTAGE (V)

120

1960 G11

40 80 160

17.0

16.5

16.0

15.5

15.0

14.5

14.0

13.5 20 60 100 140

BATTERY CURRENT (mA)

3500

3000

2500

2000

1500

1000

500

0

TYPICAL PERFOR A CE CHARACTERISTICS

Voltage Accuracy

100

DCIN = 24V

= 25°C

T

A

75

50

25

–25

–50

OUTPUT VOLTAGE ERROR (mV)

–75

–100

I

LOAD

0

250 450

= 100mA

650 1050850

VDAC VALUE

1250

1450

1960 G09

Dual vs Sequential Charging

3500 3000 2500 2000 1500 1000

500

0 3500 3000 2500 2000

BATTERY CURRENT (mA)

1500 1000

500

0

BATTERY TYPE: 10.8V Li-Ion (MOLTECH NI2020) REQUESTED CURRENT = 3A REQUESTED VOLTAGE = 12.3V MAX CHARGER CURRENT = 4.1A

BAT1

CURRENT

50

BAT1 CURRENT

100 150 200 250 300

TIME (MINUTES)

BAT2 CURRENT

MINUTES

SEQUENTIAL

DUAL

100

LTC1960

Dual Charging Batteries with Different Charge State

1960 G10

12.0

11.0

10.0

9.0

8.0

12.0

11.0

BATTERY VOLTAGE (V)

10.0

9.0

8.0

Dual vs Sequential Discharge

BAT1

VOLTAGE

BAT2

VOLTAGE

BAT2

VOLTAGE

BAT1

VOLTAGE

60 80 100 140

20 180

0

40

TIME (MINUTES)

BATTERY TYPE: 10.8V Li-Ion(MOLTECH NI2020) LOAD CURRENT = 3A

DUAL

SEQUENTIAL

11

MINUTES

120

160

1960 G12

Dual vs Sequential Discharge

15

14

13

12

11

10

15

14

13

BATTERY VOLTAGE (V)

12

11

10

20

0

BATTERY TYPE: 12V NIMH (MOLTECH NJ1020) LOAD: 33W

BAT2

VOLTAGE

BAT1

VOLTAGE

40

TIME (MINUTES)

BAT2

VOLTAGE

BAT1

VOLTAGE

60 80 100 140

DUAL

SEQUENTIAL

MINUTES

16

120

1960 G13

1960fa

7

LTC1960

PIN FUNCTIONS

UUU

(G/UHF)

Input Power Related

SCN (Pin 4/Pin 30): PowerPath Current Sensing Negative

Input. This pin should be connected directly to the “bottom” (output side) of the low valued resistor in series with the three PowerPath switch pairs, for detecting shortcircuit current events. Also powers LTC1960 internal circuitry when all other sources are absent.

SCP (Pin 5/Pin 31): PowerPath Current Sensing Positive Input. This pin should be connected directly to the “top” (switch side) of the low valued resistor in series with the three PowerPath switch pairs, for detecting short-circuit current events.

GDCO (Pin 6/Pin 32): DCIN Output Switch Gate Drive. Together with GDCI, this pin drives the gate of the Pchannel switch in series with the DCIN input switch.

GDCI (Pin 7/Pin 33): DCIN Input Switch Gate Drive. Together with GDCO, this pin drives the gate of the Pchannel switch connected to the DCIN input.

GB1O (Pin 8/Pin 34): BAT1 Output Switch Gate Drive. Together with GB1I, this pin drives the gate of the Pchannel switch in series with the BAT1 input switch.

GB1I (Pin 9/Pin 35): BAT1 Input Switch Gate Drive. Together with GB1O, this pin drives the gate of the Pchannel switch connected to the BAT1 input.

GB2O (Pin 10/Pin 36): BAT2 Output Switch Gate Drive. Together with GB2I, this pin drives the gate of the Pchannel switch in series with the BAT2 input switch.

GB2I (Pin 11/Pin 37): BAT2 Input Switch Gate Drive. Together with GB2O, this pin drives the gate of the Pchannel switch connected to the BAT2 input.

CLP (Pin 24/Pin 13): This is the Positive Input to the Supply Current Limiting Amplifier CL1. The threshold is set at 100mV above the voltage at the DCIN pin. When used to limit supply current, a filter is needed to filter out the switching noise.

Battery Charging Related

V

(Pin 13/Pin 1): The Tap Point of a Programmable

SET

Resistor Divider which Provides Battery Voltage Feedback to the Charger. A capacitor from CSN to V V

to GND provide necessary compensation and filter-

SET

ing for the voltage loop.

(Pin 14/Pin 2): This is the Control Signal of the Inner

I

TH

Loop of the Current Mode PWM. Higher I to higher charging current in normal operation. A capacitor of at least 0.1µF to GND filters out PWM ripple. Typical full-scale output current is 30µA. Nominal voltage range for this pin is 0V to 2.4V.

I

(Pin 15/Pin 3): A Capacitor from I

SET

Required to Filter Higher Frequency Components from the Delta-Sigma IDAC.

CSN (Pin 22/Pin 11): Current Amplifier CA1 Input. Connect this to the common output of the charger MUX switches.

CSP (Pin 23/Pin 12): Current Amplifier CA1 Input. This pin and the CSN pin measure the voltage across the sense resistor, RSNS, to provide the instantaneous current signals required for both peak and average current mode operation.

COMP1 (Pin 25/Pin 14): This is the Compensation Node for the Amplifier CL1. A capacitor is required from this pin to GND if input current amplifier CL1 is used. At input adapter current limit, this node rises to 1V. By forcing COMP1 low, amplifier CL1 will be defeated (no adapter current limit). COMP1 can source 10µA.

BGATE (Pin 27/Pin 16): Drives the Bottom External MOSFET of the Battery Charger Buck Converter.

SW (Pin 30/Pin 19): Connected to Source of Top External MOSFET Switch. Used as reference for top gate driver.

BOOST (Pin 31/Pin 20): Supply to Topside Floating Driver. The bootstrap capacitor is returned to this pin. Voltage swing at this pin is from a diode drop below VCC to (DCIN + VCC).

and one from

SET

corresponds

TH

to Ground is

SET

8

1960fa

LINEAR TECHNOLOGY LTC1960 Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual