DS2756E+TR MAXIM [Maxim Integrated Products], DS2756E+TR Datasheet - Page 4

• Manufacturer Part Number: DS2756E+TR
• Description: High-Accuracy Battery Fuel Gauge with Programmable Suspend Mode
• Manufacturer: MAXIM [Maxim Integrated Products]

DETAILED DESCRIPTION
The DS2756 performs temperature, voltage, and current measurement to a resolution sufficient to support process-
monitoring applications such as battery charge control and remaining capacity estimation. Temperature is
measured using an on-chip sensor, eliminating the need for a separate thermistor. Bidirectional current
measurement supporting current accumulation (coulomb counting) is accomplished using an external current
sense resistor.
The host system can configure the DS2756 to signal critical conditions to reduce polling overhead. The alarm
interrupt fires when programmable upper and lower thresholds of temperature or coulomb count are crossed. The
user can select either the DQ pin or PIO pin as the alarm interrupt signal.
PIO can also function as a Suspend mode interrupt output to reduce idle current drain within a battery pack. In
Suspend mode, the DS2756 cycles between Active and Suspend power modes to reduce DS2756 supply current
and the PIO pin can be used to wake up a microcontroller or other pack circuitry if current flowing through the pack
exceeds programmable charge and discharge thresholds (See Figure 12). The interval between current
measurements can be programmed to achieve an average current as low as 10mA (See Table 3).
As a general purpose I/O pin, PIO allows the host system to sense and control other electronics in the pack,
including switches, vibration motors, speakers, and LEDs.
Three types of memory are provided on the DS2756 for battery information storage: EEPROM, lockable EEPROM,
and SRAM. EEPROM memory saves important battery data in true NV memory that is unaffected by severe battery
depletion, accidental shorts, or ESD events. Lockable EEPROM becomes ROM when locked to provide additional
security for unchanging battery data. SRAM provides inexpensive storage for temporary data.
Figure 1. Application Example with Microcontroller in Pack
PACK+
DATA
PACK-
I
DD_MCU
UART
3.3V
Reg
µP
VDD
VSS
[Pull -up Control ]
[Data I /O]
GPIO
GPIO
INT\
4.7K
4.7K
PIO
DQ
SNS
IS2
DS2756
0.1µF
4 of 26
VIN
1K
IS1
0.020
VDD
VSS
0.1µF
5.1V
150
Protector