Rainbow Electronics DS2745 - Manual (Page 5)

DS2745 Low-Cost I 2 C Battery Monitor
5 of 14
PIN DESCRIPTION
PIN SYMBOL FUNCTION
1 SCL
Serial Clock Input. 2-Wire clock line. Input only. Connect this pin to the CLOCK
terminal of the battery pack. Pin has an internal pulldown (I
PD
) for sensing
disconnection.
2 SDA
Serial Data Input/Output. 2-Wire data line. Open-drain output driver. Connect this pin
to the DATA terminal of the battery pack. Pin has an internal pulldown (I
PD
) for sensing
disconnection.
3 PIO
General Purpose Input/Output. Open-drain output driver with input sense. Connect
to a pull up resistor for bidirectional operation.
4 SNS
Sense Resistor Connection. Connect to the negative terminal of the battery pack.
Connect the sense resistor between V
SS
and SNS.
5 V
SS
Device Ground. Connect to the negative terminal of the Li+ cell outside the cell
protection FETs. Connect the sense resistor between V
SS
and SNS.
6 CTG
Connect to Ground. Connect to the negative terminal of the Li+ cell outside the cell
protection FETs.
7 VIN Voltage Sense Input. The voltage of the Li+ cell is monitored through this input pin.
8 V
DD
Power-Supply Input. Connect to the positive terminal of the Li+ cell through a
decoupling network.
Figure 2. BLOCK DIAGRAM
2-WIRE
INTERFACE
VOLTAGE
REFERENCE
THERMAL
SENSE
ADC1
SCL
VIN
TIMEBASE
M
U
X
S
+ -
TEMPERATURE
VOLTAGE
CURRENT
ACR
STATUS
chip
ground
SNS VSS
VDD
BIAS
1k W 1k W
SDA
ADC2
PIO