ncp1593 ON Semiconductor, ncp1593 Datasheet - Page 2

• Manufacturer Part Number: ncp1593
• Description: 1 Mhz, 3 A Synchronous Buck Regulator
• Manufacturer: ON Semiconductor

PIN DESCRIPTIONS
Pin No
9, 10
2, 3
EP
1
4
5
6
7
8
VCC
PG
EN
SS
FB
Symbol
SS / NC
NC / LX
V
GND
NCP1593
V
PG
EN
LX
FB
CCP
CC
Soft−Start
Vref
Power
Good
No connect pin for NCP1593A. The user may ground this pin or leave it floating. / LX pin for NCP1593B
The drains of the internal MOSFETs. The output inductor should be connected to these pins.
Open drain output from the Power Good logic. When the FB voltage is within regulation, this is a high
impedance pin. Otherwise it is pulled low.
Logic input to enable the part. Logic high to turn on the part and a logic low to shut off the part. An intern-
al pullup forces the part into an enable state when no external bias is present on the pin.
Feedback input pin of the Error Amplifier. Connect a resistor divider from the converter’s output voltage
to this pin to set the converter’s regulated voltage.
An external capacitor on this pin sets the soft−start ramp time. Leaving this pin open sets the soft−start
time at 500 ms. For NCP1593B this pin is a no connect and should be left floating.
Input supply pin for internal bias circuitry. Connect a 0.1 mF ceramic bypass capacitor to this pin.
Input for the power stage
Exposed pad of the package provides both electrical contact to the ground and good thermal contact to
the PCB. This pad must be soldered to the PCB for proper operation.
Power Reset
Hiccup
UVLO
THD
+
+
−
gm
0.9 x Vref
Figure 1. Block Diagram
Rc1
Cc1
BLOCK DIAGRAM
http://onsemi.com
+
Cc2
2
−
+
AGND
PWM
OSC
Description
Control
Logic
CA
+
−
PMOS
M1
Ri
VCCP
LX
LX
PGND