bq78412
ZHCS297 –OCTOBER 2010 www.ti.com.cn
PIN DESCRIPTIONS
bq78412
I/O/P DESCRIPTION
NAME No.
A0 21 I Configuration input. Connect to ground.
A1 22 I Configuration input. Connect to ground.
AVDD 14 P 3.3-V power to the analog logic. Typically connected to REG33.
15
AVSS P Connect to ground.
29
BUZZER 10 O Buzzer output. Active high when alarm condition is detected.
Active high output, turns on display enable transistor. Not required in all applications. Blanks display during
DISPEN 32 O
updates.
DVDD 39 P 3.3-V supply to the digital logic. Connect a 2.2- μF capacitor to VSS. Typically connected to REG33.
DVSS 41 P Connect to ground
REG33 28 P Regulated 3.3-V power output.
RST_N 44 I Connect to external RC network for power-up reset.
31
RSVD – Reserved, no connection required.
40
RS– 17 I Current sense negative
RS+ 18 I Current sense positive
RXD 9 I UART RX data
6 O I
2
C clock output
SCL
24 I I
2
C clock for internal use. Connect to SCL pin 6.
SCLK 2 O Low-to-high transition clocks data into external serial in, parallel out shift register.
SD 7 O IR XCVR Shutdown; HIGH=XCVR in shutdown, LOW=XCVR Active
5 I/O I
2
C data
SDA
23 I/O I
2
C data for internal use. Connect to SDA pin 5.
SDAT 3 O Serial display data to serial in, parallel out shift register. A low bit turns on an LED.
TEST1 34 I/O Test pin, no connection
TEST2 35 I/O Test pin, no connection
TEST3 36 I/O Test pin, no connection
TEST4 37 I/O Test pin, no connection
TEST5 38 I/O Test pin, no connection
TXD 8 O UART TX data
VBAT+ 25 P Input to internal regulator.
VS 16 I Sense voltage. Connect to battery positive.
Input terminal of 8-MHz crystal oscillator or crystal pin. (Optional: Can be left unconnected to use internal
XIN 43 I
oscillator)
Output terminal of 8-MHz crystal oscillator or crystal pin. (Optional: Can be left unconnected to use internal
XOUT 42 O
oscillator)
1
4
11
12
13
N/C – No connection
19
20
26
27
33
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