LTC1325CSW datasheet(10/24 Pages) LINER

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LTC1325

Bit 1: Start Bit (Start)

The first “logical one” clocked into the DIN input after CS

goes low is the start bit. The start bit initiates the data

transfer and all leading zeros which precede this logical

one will be ignored. After the start bit is received, the

remaining bits of the command word will be clocked in.

Bits 2 and 3: Mode Select (MOD0 and MOD1)

The two mode bits determine which of four modes the chip

will be in: idle, discharge, charge or gas gauge.

MOD1

MOD0

DESCRIPTION

Idle

Discharge

Charge

Gas Gauge

Bit 4: Single-Ended Differential Conversion (SGL/DIFF)

SGL/DIFF determines whether the ADC makes a single-

ended measurement with respect to ground or a differen-

tial measurement with respect to the Sense pin.

SGL/DIFF

DESCRIPTION

Single-Ended ADC Conversion

Differential ADC Conversion (with respect to Sense)

COMMAND WORD

The command word is 22 bits long and contains all the

information needed to configure and control the chip. On

power-up all bits are cleared to logical “0.”

FUNCTIONAL DESCRIPTIO

START

= 1

MOD0

MOD1

SGL/

DIFF

MSBF

DS0

DS1

DS2

DIV0

DIV1

DIV2

DIV3

DR0

DR1

DR2

FSCLR

TO0

TO1

TO2

VR0

VR1

LTC1325 • F01

Figure 1. Command Word

Bit 5: MSB-First/LSB-First (MSBF)

The ADC data is programmed for MSB-first or LSB-first

sequence using the MSBF bit. See Serial I/O description

for details.

MSBF

DESCRIPTION

LSB-First Data Follows MSB-First Data

MSB-First Data Only

Bits 6 to 8: ADC Data Input Select (DS0 to DS2)

DS2, DS1 and DS0 select which circuit is connected to the

ADC input. Do not use unlisted combinations.

DS2

DS1

DS0

DESCRIPTION

Gas Gauge Output

Battery Temperature Pin, TBAT

Ambient Temperature Pin, TAMB

Battery Divider Output Voltage, VCELL

VIN Pin

Bits 9 to 12: Battery Divider Ratio Select (DIV0 to DIV3)

DIV3, DIV2, DIV1 and DIV0 select the division ratio for the

voltage divider across the battery.

DIV3

DIV2

DIV1

DIV0

DESCRIPTION

00(VBAT – VSENSE)/1

01(VBAT – VSENSE)/2

10(VBAT – VSENSE)/3

11(VBAT – VSENSE)/4

00(VBAT – VSENSE)/5

01(VBAT – VSENSE)/6

10(VBAT – VSENSE)/7

11(VBAT – VSENSE)/8

00(VBAT – VSENSE)/9

01(VBAT – VSENSE)/10

10(VBAT – VSENSE)/11

11(VBAT – VSENSE)/12

00(VBAT – VSENSE)/13

01(VBAT – VSENSE)/14

10(VBAT – VSENSE)/15

11(VBAT – VSENSE)/16

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