CS51411, CS51412, CS51413, CS51414

http://onsemi.com

2

PIN CONNECTIONS

1

2

3

4

5

6

7

8

9

18

17

16

15

14

13

12

11

10

BOOST

Vsw

SHDNB

NC

NC

NC

NC

GND

NC

NC

SYNC

SYNC

SHDNB

18

GND

BOOST

SHDNB

BIAS

18

GND

BOOST

CS51412/4

CS51411/3

CS51411/3

1

2

3

4

5

6

7

8

9

18

17

16

15

14

13

12

11

10

BOOST

Vsw

BIAS

NC

NC

NC

NC

GND

NC

NC

SHDNB

CS51412/4

PACKAGE PIN DESCRIPTION

SOIC−8

Package Pin #

DFN18

Package Pin #

Pin Symbol

Function

1

1

BOOST

The BOOST pin provides additional drive voltage to the on−chip NPN

power transistor. The resulting decrease in switch on voltage increases

efficiency.

2

2, 3, 4

This pin is the main power input to the IC.

3

5, 6, 7

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

(CS51412/CS51414)

8

BIAS

The BIAS pin connects to the on−chip power rail and allows the IC to run

most of its internal circuitry from the regulated output or another low

voltage supply to improve efficiency. The BIAS pin is left floating if this

feature is not used.

5

(CS51411/CS51413)

10

SYNC

This pin provides the synchronization input.

5

(CS51412/CS51414)

4

(CS51411/CS51413)

10

(CS51412/CS51414)

8

(CS51411/CS51413)

SHDNB

Shutdown_bar input. This is an active−low logical input, TTL compatible,

with an internal pull−up current source. The IC goes into sleep mode,

drawing less than 85 mA when the pin voltage is pulled below 1.0 V. This

pin may be left floating in applications where a shutdown function is not

required.

6

13

GND

Power return connection for the IC.

7

16

The FB pin provides input to the inverting input of the error amplifier. If

current limit folds back to about 1 A. These features protect the IC under

severe overcurrent or short circuit conditions.

8

17

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.

−

9, 11, 12, 14, 15, 18

NC

No Connection