NCV8843
PACKAGE PIN DESCRIPTION
SO−8
SO−16W
EPAD
DFN−18
PIN
SYMBOL
FUNCTION
1
15
1
BOOST The BOOST pin provides additional drive voltage to the on−chip NPN power tran-
sistor. The resulting decrease in switch on voltage increases efficiency.
2
16
2−4
VIN
This pin is the main power input to the IC.
3
1
5−7
VSW
This is the connection to the emitter of the on−chip NPN power transistor and
serves as the switch output to the inductor. This pin may be subjected to negative
voltages during switch off−time. A catch diode is required to clamp the pin voltage
in normal operation. This node can stand −1.0 V for less than 50 ns during switch
node flyback.
4
2
8
SHDNB The shutdown pin is active low and TTL compatible. The IC goes into sleep mode,
drawing less than 1.0 mA when the pin voltage is pulled below 1.0 V.
This pin should be pulled up to VCC with resistor.
SYNC External synchronization single input, with 60k internal pull−down resistor. If not
5
7
10
used, leave unconnected or connect to GND.
6
8
13
GND Power return connection for the IC.
7
9
16
VFB
The FB pin provides input to the inverting input of the error amplifier. If VFB is lower
than 0.29 V, the oscillator frequency is divided by four, and current limit folds back
to about 1 A. These features protect the IC under severe overcurrent or short cir-
cuit conditions.
8
10
17
VC
The VC pin provides a connection point to the output of the error amplifier and
input to the PWM comparator. Driving of this pin should be avoided because on−
chip test circuitry becomes active whenever current exceeding 0.5 mA is forced
into the IC.
−
3 − 6,
9, 11, 12,
NC
No Connection
11 − 14 14, 15, 18
−
EPAD
EPAD
−
Exposed die attach pad. Internally connected to GND. External connection to GND
is optional.
1
BOOST
VIN
VSW
SHDNB
SO−8
8
VC
VFB
GND
SYNC
PIN CONNECTIONS
1
VSW
SHDNB
NC
NC
NC
NC
SYNC
GND
16
VIN
BOOST
NC
NC
NC
NC
VC
VFB
SO−16W EPAD
BOOST 1
VIN 2
VIN
3
VIN
4
VSW
5
VSW
6
VSW 7
SHDNB 8
NC 9
18 NC
17 VC
16 VFB
15 NC
14 NC
13 GND
12 NC
11 NC
10 SYNC
DFN18
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