NCP1511

http://onsemi.com

2

Figure 3. Simplified Block Diagram

+

−

−

+

+

−

+

−

+

−

+

−

FB

GNDA

CB0

CB1

SHD

ISENS

ISENS

SENFET

ILIM

ZCL

MODE SELECTION

SYNC DETECT

AND

TIMING BLOCK

SYNC DETECT

AND

TIMING BLOCK

THERMAL

SHUTDOWN

ENABLE

DETECT

SELECT

LOGIC

BANDGAP

REFERENCE

AND SOFT

START

PWM

OVP

PM

CMP

CMP

CMP

CMP

CMP

OA

Q2

Q1

DVR

DVR

COMPENSATION

RAMP

CONTROL

BLOCK

(PWM,PM)

GNDP

SYNC

LX

VCC

FB

DAMPING

SWITCHING

CONTROL

DAMPING

SWITCHING

CONTROL

PIN FUNCTION DESCRIPTION

Pin No.

Symbol

Type

Description

A1

GNDP

Power Ground

Ground Connection for the NFET Power Stage.

A2

LX

Analog Output

Connection from Power Pass Elements to the Inductor.

A3

Analog Input

B1

SYNC

Analog Input

Synchronization input for the PWM converter. If a clock signal is present, the converter

uses the rising edge for the turn on. If this pin is low, the converter is in the Pulsed mode.

If this pin is high, the converter uses the internal oscillator for the PWM mode. This pin

contains an internal pull down resistor.

B2

GNDA

Analog Ground

Ground connection for the Analog Section of the IC. This is the GND for the FB, Ref,

Sync, CB, and SHD pins.

B3

FB

Analog Input

Feedback Voltage from the Output of the Power Supply.

C1

SHD

Analog Input

Enable for Switching Regulator. This Pin is Active High to enable the NCP1511. The SHD

Pin has an internal pull down resistor to force the converter off if this pin is not connected

to the external circuit.

C2

CB1

Analog Input

C3

CB0

Analog Input