SM8172A Datasheet, PDF (2/17 Pages) Nippon Precision Circuits Inc – 2-output Power Supply IC

6. PINOUT
(Top view)
SM8172A
VIN2 1
LDOUT 2
GND 3
ENDCO 4
ENLDO 5
10 RESETN
9 FB
8 VIN1
7 LX
6 PGND
7. PIN DESCRIPTION
Number
1
2
3
4
5
6
7
8
9
10
Name
VIN2
LDOUT
GND
ENDCO
ENLDO
PGND
LX
VIN1
FB
RESETN
I/O
Function
–
Supply voltage (series regulator, internal circuits)^*1
O
Series regulator output^*2
–
Ground (internal circuits)
Ip ^*3
Output enable (DC/DC converter)
Ip ^*3
Output enable (series regulator)
–
Ground (DC/DC converter output circuit)
O
DC/DC converter coil drive^*4
–
Supply voltage (DC/DC converter output circuit)^*1
I
DC/DC converter feedback connection^*5
O
Reset signal output (active-LOW, open-drain output)^*6
*1. VIN1 and VIN2 should have the same voltage potential.
*2. When the series regulator is not used, LDOUT pin should be open and not be connected to GND.
*3. Ip = Input with pull-down resistor built-in
*4. When the DC/DC converter is not used, LX pin should be open and not be connected to GND or the supply.
*5. When the DC/DC converter is not used, FB pin should be connected to GND.
*6. When the reset signal is not used, RESETN pin should be connected to GND.
8. BLOCK DIAGRAM
5.0V
10µF
VIN2
GND
ENDCO
ENLDO
VIN2
detector
Delay
circuits
Current
−
protection
ERR
+
Soft
start
Vref
Thermal
ERR
protection
OSC
Current mode
PWM control
Soft
start
Current
protection
Output
control
RESETN
10kΩ
RESETN output
LDOUT
3.3µF
LDOUT output
(3.3V)
FB
330kΩ
VIN1
5.0V
10µF
LX
2.2µH
PGND
8pF 220kΩ
4.7µF
DCOUT
(1.0V)
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