General Description

The DS2129 is a triple-output voltage regulator for

27-line, low-voltage-differential (LVD) SCSI termination

for SPI-2 and SPI-3 applications using LVD termination

networks. The device provides reference voltages and

bias currents for LVD-termination resistor pi (

π) net-

works. With a pi network (475

Ω, 121Ω, 475Ω), the

DS2129 meets the common-mode bias, differential

bias, and termination-impedance requirements of SPI-2

(Ultra2) and SPI-3 (Ultra3). The device also provides a

1.3V output for DIFFSENSE signaling, and includes pro-

tection features such as thermal shutdown and active

current limiting.

Applications

SCSI Array Backplane

SCSI Cables

Features

♦ Fully Compliant with SPI-2 and SPI-3

♦ 2.7V to 5.25V Operation

♦ Differential Fail-Safe Bias

LVD SCSI 27-Line Regulator

______________________________________________ Maxim Integrated Products

1

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

N.C.

N.C.

N.C.

HS_GND

HS_GND

HS_GND

HS_GND

N.C.

N.C.

TOP VIEW

SO (150 mils)

TERMPWR

REG2

REG1

GND

HS_GND

DIFFSENSE

N.C.

DS2129

Pin Configuration

Ordering Information

Block Diagram

Rev 1; 2/06

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART*

VOLTAGE (V)

PIN-

PACKAGE

TOP

MARK**

DS2129S

5

16 SO

DS2129

DS2129S+

5

16 SO

DS2129

DS2129S/T&R

5

16 SO

DS2129

DS2129S+T&R

5

16 SO

DS2129

BANDGAP

(1.25V)

THERMAL

SHUTDOWN

REF125

PTAT

REF175

TS

1.75V

REG2

REG1

DIFFSENSE

1.3V

REF075

0.75V

REF130

REFERENCES

TS

TS

TS

TERMPWR

GND

DS2129

+Denotes lead-free package.

*All devices rated for the commercial (0°C to +70°C) tempera-

ture range.

**A “+” anywhere on the topmark denotes a lead-free package.