POWER MANAGEMENT

1

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SC1110

Sink and Source DC/DC Controller for

Termination Power Supply Applications

Features

Applications

Revision: July 20, 2004

Typical Application Circuit

Description

The SC1110 is a low-cost, full featured, synchronous

voltage-mode controller designed to generate

termination voltage in double data rate (DDR) memory

systems and other applications where wide data bus

need to be actively terminated. Synchronous control of

the MOSFET half bridge allows power flowing

bi-directionally. The termination voltage can be tightly

regulated to track the chipset voltage, i.e. to be exactly

50% of that at all times.

The SC1110 is ideal for low cost implementation of

termination voltage supplies. SC1110 features include

temperature compensated voltage reference, triangle

wave oscillator and current sense comparator circuitry,

and allows the use of inexpensive N-channel power

MOSFETs.

The SC1110 operates at a fixed 250kHz, providing an

optimum compromise between efficiency, transient

performance, external component size, and cost.

Generates termination voltages for active termina-

tion schemes

1% set point accuracy

For ±7A output current, transient regulation is

better than ±80mV

V

to allow termination voltage track of the chip set

voltage

Buffered V

R

mode

Soft start and logic input enabling

250kHz switching for best transient and efficiency

performance

Gate drive capable for 0.5A sourcing and sinking

For DDR memory systems

For active termination schemes in high speed logic

systems

Q1

Si9426DY

Q2

Si9426DY

R8

2.2

R3

10

L1

800 nH

D1

MBRM120

C6

1.0

C12-14

3 x 560uF

C10,11

2 x 560uF

R6

4.7k

C2

0.1

C4

0.022

C1

0.01

R2

1.24k

REFOUT

SS/ENBL

+

_

+

_

Vin 2.5V

Vout = 1.25V @ 7A

+5Vcc

R7

2.2

C8,9

2 x 10uF

C7

1.0

C5

0.047

C15-24

10 x 10uF

C10-14: Sanyo, 4SP560M

C8,9,15-24: TDK, CC3216AX5R0J106K

Q1,Q2 options: Si9426DY, FDS6890A, IRF7401

D1: ON Semi (Motorola)

L1: Panasonic, ETQP6F0R8L or Falco, QPIP1205-809-3

R4

1k

R5

1k

C3

0.1

VCC

1

REFOUT

14

SS/ENBL

2

OCSET

3

GND

5

PHASE

6

DL

7

DH

8

BSTH

9

BSTL

10

COMP

11

SENSE

12

REFIN

13

PWRGD

4

U1

SC1110

PWRGD

R1

5k

C25

0.1