DS2762 High-Precision Li+ Battery Monitor With Alerts

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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

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

S2

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 Resistor

6.25

mVhrs for External Sense Resistor

Current Accumulator Interrupt Low Threshold

MSB—Address 82

LSB—Address 83

S2

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 Resistor

6.25

mVhrs for External Sense Resistor