ISL88731
ChargeCurrent registers. Use the Write-Word protocol
Setting Charge Voltage
(Figure 18) to write to the ChargeVoltage register. The
register address for ChargeVoltage is 0x15. The 16-bit
binary number formed by D15–D0 represents the charge
voltage set point in mV. However, the resolution of the
ISL88731 is 16mV because the D0–D3 bits are ignored as
shown in Table 2. The D15 bit is also ignored because it is
not needed to span the 1.024V to 19.2V range. Table 2
shows the mapping between the charge-voltage set point
and the 16-bit number written to the ChargeVoltage register.
The ChargeVoltage register can be read back to verify its
contents.
Charge voltage is set by writing a valid 16-bit number to the
ChargeVoltage register. This 16-bit number translates to a
65.535V full-scale voltage. The ISL88731 ignores the first 4
LSBs and uses the next 11 bits to set the voltage DAC. The
charge voltage range of the ISL88731 is 1.024V to 19.200V.
Numbers requesting charge voltage greater than 19.200V
result in a ChargeVoltage of 19.200V. All numbers
requesting charge voltage below 1.024V result in a voltage
set point of zero, which terminates charging. Upon initial
power up or reset, the ChargeVoltage and ChargeCurrent
registers are reset to 0 and the charger remains shut down
until valid numbers are sent to the ChargeVoltage and
TABLE 2. CHARGEVOLTAGE (REGISTER 0x15)
DESCRIPTION
BIT
0
BIT NAME
Not used.
Not used.
Not used.
Not used.
1
2
3
4
Charge Voltage, DACV 0
Charge Voltage, DACV 1
Charge Voltage, DACV 2
Charge Voltage, DACV 3
Charge Voltage, DACV 4
Charge Voltage, DACV 5
Charge Voltage, DACV 6
Charge Voltage, DACV 7
Charge Voltage, DACV 8
Charge Voltage, DACV 9
Charge Voltage, DACV 10
0 = Adds 0mV of charger voltage, 1024mV min.
1 = Adds 16mV of charger voltage.
5
6
0 = Adds 0mV of charger voltage, 1024mV min.
1 = Adds 32mV of charger voltage.
0 = Adds 0mV of charger voltage, 1024mV min.
1 = Adds 64mV of charger voltage.
7
0 = Adds 0mV of charger voltage, 1024mV min.
1 = Adds 128mV of charger voltage.
8
0 = Adds 0mV of charger voltage, 1024mV min.
1 = Adds 256mV of charger voltage.
9
0 = Adds 0mV of charger voltage, 1024mV min.
1 = Adds 512mV of charger voltage.
10
11
12
13
14
15
0 = Adds 0mA of charger voltage.
1 = Adds 1024mV of charger voltage.
0 = Adds 0mV of charger voltage.
1 = Adds 2048mV of charger voltage.
0 = Adds 0mV of charger voltage.
1 = Adds 4096mV of charger voltage.
0 = Adds 0mV of charger voltage.
1 = Adds 8192mV of charger voltage.
0 = Adds 0mV of charger voltage.
1 = Adds 16384mV of charger voltage, 19200mV max.
Not used. Normally a 32768mV weight.
FN9258.0
November 20, 2006
12
INTERSIL [ Intersil ]
