Datasheet

DS2762 High-Precision Li+ Battery Monitor With Alerts
13 of 25
PROGRAMMABLE I/O
To use the PIO pin as described in this section, the IE bit (bit 2) of the Status Register must be set to 0.
To use the PIO pin as an output, write the desired output value to the PIO bit in the special feature register. Writing
a 0 to the PIO bit enables the PIO output driver, pulling the PIO pin to V
SS
. Writing a 1 to the PIO bit disables the
output driver, allowing the PIO pin to be pulled high or used as an input. To sense the value on the PIO pin, read
the PIO bit. The DS2762 turns off the PIO output driver and sets the PIO bit high when in sleep mode or when DQ
is low for more than 2s, regardless of the state of the PMOD bit.
ALARM COMPARATORS
The PIO pin can be programmed as an interrupt output (active low) to alert the host system of critical events. To
use the Interrupt feature, the Interrupt Enable (IE) bit (bit 2) of the Status Register must be set to a 1. Interrupt
threshold values can be programmed by the user in the designated SRAM memory registers in the formats and
locations found in Figure 9. Since these thresholds are located in SRAM memory, they must be reprogrammed if a
loss of power to the DS2762 occurs. The PIO line will go low to interrupt the system host and indicate that one of
the following events has occurred:
· Accumulated Current ³ Current Accumulator Interrupt High Threshold
· Accumulated Current £ Current Accumulator Interrupt Low Threshold
· Temperature ³ Temperature Interrupt High Threshold
· Temperature £ Temperature Interrupt Low Threshold
The host may then poll the DS2762 to determine which threshold has been met or exceeded.
Figure 9. Interrupt Threshold Register Formats
Current Accumulator Interrupt High Threshold
MSB—Address 80 LSB—Address 81
S 2
14
2
13
2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
MSb LSb MSb LSb
Units: 0.25mAhrs for Internal Sense Resisto
r
6.25mVhrs for External Sense Resisto
r
Current Accumulator Interrupt Low Threshold
MSB—Address 82 LSB—Address 83
S 2
14
2
13
2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
MSb LSb MSb LSb
Units: 0.25mAhrs for Internal Sense Resisto
r
6.25mVhrs for External Sense Resisto
r