SMBus Interface

The MAX8713 receives control inputs from the SMBus

interface. The serial interface complies with the SMBus

protocols as documented in the System Management

Bus Specification V1.1, which can be downloaded from

www.smbus.org. The MAX8713 uses the SMBus Read-

Word and Write-Word protocols (Figure 5) to communi-

cate with the smart battery. The MAX8713 is an SMBus

slave device and does not initiate communication on

the bus. It responds to the 7-bit address 0b0001001_

(0x12). In addition, the MAX8713 has two identification

(ID) registers: a 16-bit device ID register and a 16-bit

manufacturer ID register.

The data (SDA) and clock (SCL) pins have Schmitt-trig-

ger inputs that can accommodate slow edges. Choose

pullup resistors for SDA and SCL to achieve rise times

according to the SMBus specifications.

Communication starts when the master signals a START

condition, which is a high-to-low transition on SDA,

while SCL is high. When the master has finished com-

municating, the master issues a STOP condition, which

is a low-to-high transition on SDA, while SCL is high.

Simplified Multichemistry

SMBus Battery Charger

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13

Table 1. ChargeVoltage()

BIT

BIT NAME

DESCRIPTION

0—

Not used. Normally a 1mV weight.

1—

Not used. Normally a 2mV weight.

2—

Not used. Normally a 4mV weight.

3—

Not used. Normally an 8mV weight.

4

Charge Voltage, DACV 0

0 = Adds 0mV of charge-voltage compliance, 1024mV (min).

1 = Adds 16mV of charge-voltage compliance.

5

Charge Voltage, DACV 1

0 = Adds 0mV of charge-voltage compliance, 1024mV (min).

1 = Adds 32mV of charge-voltage compliance.

6

Charge Voltage, DACV 2

0 = Adds 0mV of charge-voltage compliance, 1024mV (min).

1 = Adds 64mV of charge-voltage compliance.

7

Charge Voltage, DACV 3

0 = Adds 0mV of charge-voltage compliance, 1024mV (min).

1 = Adds 128mV of charge-voltage compliance.

8

Charge Voltage, DACV 4

0 = Adds 0mV of charge-voltage compliance, 1024mV (min).

1 = Adds 256mV of charge-voltage compliance.

9

Charge Voltage, DACV 5

0 = Adds 0mV of charge-voltage compliance, 1024mV (min).

1 = Adds 512mV of charge-voltage compliance.

10

Charge Voltage, DACV 6

0 = Adds 0mV of charge-voltage compliance.

1 = Adds 1024mV of charge-voltage compliance.

11

Charge Voltage, DACV 7

0 = Adds 0mV of charge-voltage compliance.

1 = Adds 2048mV of charge-voltage compliance.

12

Charge Voltage, DACV 8

0 = Adds 0mV of charge-voltage compliance.

1 = Adds 4096mV of charge-voltage compliance.

13

Charge Voltage, DACV 9

0 = Adds 0mV of charge-voltage compliance.

1 = Adds 8192mV of charge-voltage compliance.

14

Charge Voltage, DACV 10

0 = Adds 0mV of charge-voltage compliance.

1 = Adds 16,384mV of charge-voltage compliance, 19,200mV (max).

15

—

Not used. Normally a 32,768mV weight.

Command: 0x15