ST LD1085CDT-R User Manual

3 A low-drop, adjustable positive voltage regulator

Features

■ Typical dropout 1.3 V (at 3 A)

■ Three terminal adjustable output voltage

■ Guaranteed output current up to 3 A

■ Output tolerance ± 2 % at 25 °C and ± 3 % in

full temperature range

■ Internal power and thermal limit

■ Wide operating temperature range -40 °C to

125 °C

■ Package available: DPAK

■ Pinout compatibility with standard adjustable

VREG

Description

LD1085CXX

DPAK

The LD1085C is a low drop voltage regulator able
to provide up to 3 A of output current. Dropout is
guaranteed at a maximum of 1.5 V at the
maximum output current, decreasing at lower
loads. The LD1085C is pin to pin compatible with
the older 3-terminal adjustable regulators, but has
better performances in term of drop and output
tolerance.

A 2.85 V output version is suitable for SCSI-2
active termination. Unlike PNP regulators, where
a part of the output current is wasted as quiescent
current, the LD1085C quiescent current flows into
the load, so increase efficiency. Only a 10 µF
minimum capacitor is need for stability.

The device is supplied in DPAK. On chip trimming
allows the regulator to reach a very tight output
voltage tolerance, within ± 2 % at 25 °C.

Table 1. Device summary

Order codes Packages

LD1085CDT-R DPAK (tape and reel)

April 2008 Rev 8 1/16

www.st.com

16

Contents LD1085CXX

Contents

1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Schematic application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

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LD1085CXX Diagram

1 Diagram

Figure 1. Schematic diagram

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Pin configuration LD1085CXX

2 Pin configuration

Figure 2. Pin connections (top view)

DPAK

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LD1085CXX Maximum ratings

3 Maximum ratings

Table 2. Absolute maximum ratings

Symbol Parameter Value Unit

DC input voltage 30 V

Output current Internally limited

Power dissipation Internally limited

Storage temperature range -55 to +150 °C

Operating junction temperature range -40 to +125 °C

T

P

T

V

I

I

O

D

STG

OP

Note: Absolute maximum ratings are those values beyond which damage to the device may occur.

Functional operation under these condition is not implied.

Table 3. Thermal data

Symbol Parameter DPAK Unit

R

R

thJC

thJA

Thermal resistance junction-case 3 °C/W

Thermal resistance junction-ambient 62.5 °C/W

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