Pin description – Rainbow Electronics DS2788 User Manual
Page 5
D
S
2
7
8
8
Stand-Alone Fuel-Gauge IC with
LED Display Drivers
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5
Pin Description
PIN
NAME
FUNCTION
1
LED2
Display Driver. Connect to an LED connected to V
DD
for display of relative pack capacity.
2
LED1
Display Driver. Connect to an LED connected to V
DD
for display of relative pack capacity.
3
DV
SS
Display Ground. Ground connection for the LED display drivers. Connect to V
SS
.
4
V
DD
Power-Supply Input. Connect to the positive terminal of the battery cell through a decoupling network.
5
OVD
1-Wire Bus Speed Control. Input logic level selects the speed of the 1-Wire bus. Logic 1 selects overdrive (OVD)
and Logic 0 selects standard (STD) timing. On a multidrop bus, all devices must operate at the same speed.
6
V
SS
Device Ground. Connect directly to the negative terminal of the battery cell. Connect the sense resistor
between V
SS
and SNS.
7
DQ
Data Input/Output. 1-Wire data line, open-drain output driver. Connect this pin to the DATA terminal of the
battery pack. This pin has a weak internal pulldown (I
PD
) for sensing pack disconnection from host or charger.
8
VMA
Voltage Measurement Active. Output is driven high before the start of a voltage conversion and driven low at
the end of the conversion cycle.
9
SNS
Sense Resistor Connection. Connect to the negative terminal of the battery pack. Connect the sense resistor
between V
SS
and SNS.
10
V
IN
Voltage Sense Input. The voltage of the battery cell is monitored through this input pin.
11
PIO
Programmable I/O Pin. Can be configured as input or output to monitor or control user-defined external
circuitry. Output driver is open drain. This pin has a weak internal pulldown (I
PD
). When configured as an input,
upon recognition of a rising edge, the fuel-gauge display is enabled.
12
LED5
Display Driver. Connect to an LED connected to V
DD
for display of relative pack capacity. Leave floating in
LED4 configuration.
13
LED4
Display Driver. Connect to an LED connected to V
DD
for display of relative pack capacity.
14
LED3
Display Driver. Connect to an LED connected to V
DD
for display of relative pack capacity.
STATUS
AND
CONTROL
TIME BASE
BIAS/VREF
1-Wire
INTERFACE
EEPROM
ACCUMULATED
CURRENT
CURRENT ADC
15-BIT + SIGN
TEMP
AND
VOLTAGE
ADC
LED
DRIVERS
RATE AND
TEMPERATURE
COMPENSATION
EN
V
POR
V
DD
PIO
DQ
OVD
SNS
LED5
LED4
LED3
LED2
LED1
DV
SS
VMA
V
IN
V
SS
DS2788
Figure 1. Block Diagram