ncp1578 ON Semiconductor, ncp1578 Datasheet - Page 4

• Manufacturer Part Number: ncp1578
• Description: Synchronous Step Down Controller With 50ma Linear Regulator
• Manufacturer: ON Semiconductor

PIN FUNCTION DESCRIPTION
Pin No.
10
11
12
13
14
15
16
17
18
19
20
21
1
2
3
4
5
6
7
8
9
EN_LDO
PGOOD
Symbol
EN_SW
OCSET
PGDLY
THPAD
FPWM
COMP
AGND
PGND
VCCP
FOFF
LDO5
VBAT
VBST
SWN
NC
SS
BG
TG
FB
FPWM or Power Saving Control. Logic high enables force PWM. Logic low enables power saving
operation.
LDO enable input. The 5 V LDO is enabled if EN_LDO is high and disabled if it is low. This pin can
sustain voltage as high as VBAT.
Input pin for over current threshold setting for high side gate driver. Also it is for the internal ramp gen‐
erator to implement the voltage feed forward rejection to the input voltage variation
Fault OFF. If it pulls to high, it disables the features of OCP, UVLO and OVP. Normally it should be tied
to ground. This pin is internally pulled down.
PWM controller's enable input. The switching controller is enabled if EN_SW is high and disabled if
EN is low.
5.0 V linear regulator output.
Battery/adaptor voltage input.
Analog ground.
Not connected
Feedback input from controller's output voltage.
Error amplifier output pin.
Soft-start (for switcher) capacitor connection to ground.
Power good signal open drain output. High impedance (open drain) if power is good (in regulation).
Low impedance if power is not good.
Power good delay capacitor connection to ground.
Power ground.
Gate driver output for low-side N-Channel power FET.
Power Input voltage pin.
Inductor driven node of the SMPS, the return for high-side gate driver, and also serve as the lower
supply rail of the high-side gate driver of the SMPS.
Gate driver output for high-side N-Channel power FET.
Positive supply of high-side gate driver of the SMPS. Connect boost capacitor between this pin and
switching node SWN of the SMPS.
Copper pad on bottom of IC used for heatsinking. This pin should be connected to the ground plane
under the IC.
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NCP1578
4
Description