isl88731a

Manufacturer Part Numberisl88731a
DescriptionSmbus Level 2 Battery Charger
ManufacturerIntersil Corporation
isl88731a datasheet
 


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Write To A Register
SLAVE
REGISTER
S
A
ADDR + W
Read From A Register
SLAVE
REGISTER
S
A
ADDR + W
S
START
P
STOP
FIGURE 19. SMBus/ISL88731A READ AND WRITE PROTOCOL
Byte Format
Every byte put on the SDA line must be eight bits long and
must be followed by an acknowledge bit. Data is transferred
with the most significant bit first (MSB) and the least
significant bit last (LSB).
ISL88731A and SMBus
The ISL88731A 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 ISL88731A uses the SMBus
Read-Word and Write-Word protocols (Figure 19) to
communicate with the smart battery. The ISL88731A is an
SMBus slave device and does not initiate communication on
the bus. It responds to the 7-bit address 0b0001001_ (0x12).
Read address = 0b00010011 and
Write address = 0b00010010.
In addition, the ISL88731A has two identification (ID)
registers: a 16-bit device ID register and a 16-bit
manufacturer ID register.
REGISTER
ADDRESS
REGISTER NAME
0x14
ChargeCurrent
0x15
ChargeVoltage
0x3F
InputCurrent
0xFE
ManufacturerID
0xFF
DeviceID
12
ISL88731A
LO BYTE
HI BYTE
A
A
ADDR
DATA
DATA
SLAVE
A
P
S
ADDR
ADDR + R
A
ACKNOWLEDGE
N
NO ACKNOWLEDGE
The data (SDA) and clock (SCL) pins have Schmitt-trigger
inputs that can accommodate slow edges. Choose pull-up
resistors for SDA and SCL to achieve rise times according to
the SMBus specifications. The ISL88731A is controlled by
the data written to the registers described in Table 1.
Battery Charger Registers
The ISL88731A supports five battery-charger registers that
use either Write-Word or Read-Word protocols, as
summarized in Table 1. ManufacturerID and DeviceID are
“read only” registers and can be used to identify the
ISL88731A. On the ISL88731A, ManufacturerID always
returns 0x0049 (ASCII code for “I” for Intersil) and DeviceID
always returns 0x0001.
Enabling and Disabling Charging
After applying power to ISL88731A, the internal registers
contain their POR values (see Table 1). The POR values for
charge current and charge voltage are 0x0000. These
values disable charging. To enable charging, the
ChargeCurrent register must be written with a number
>0x007F and the ChargeVoltage register must be written
with a number >0x000F. Charging can be disabled by writing
0x0000 to either of these registers.
TABLE 1. BATTERY CHARGER REGISTER SUMMARY
READ/WRITE
Read or Write
6-bit Charge Current Setting
Read or Write
11-bit Charge Voltage Setting
Read or Write
6-bit Charge Current Setting
Read Only
Manufacturer ID
Read Only
Device ID
A
P
LO BYTE
HI BYTE
A
A
N
DATA
DATA
DRIVEN BY THE MASTER
DRIVEN BY ISL88731
DESCRIPTION
P
POR STATE
0x0000
0x0000
0x0080
0x0049
0x0001
FN6738.1
January 7, 2009