11

LT1529

LT1529-3.3/LT1529-5

152935fb

S

APPLICATI

I FOR ATIO

In some applications it may be necessary to leave the input

to the LT1529 unconnected when the output is held high.

This can happen when the LT1529 is powered from a

rectified AC source. If the AC source is removed, then the

input of the LT1529 is effectively left floating. The reverse

pin is left open. The state of the SHDN pin will have no

floating.

When the input of the LT1529 is forced to a voltage below

its nominal output voltage and its output is held high, the

output current will follow the curve shown in Figure 3 . This

can happen if the input of the LT1529 is connected to a

discharged (low voltage) battery and the output is held up

by either a backup battery or by a second regulator circuit.

will typically drop to less than 2µA (see Figure 4). The state

of the SHDN pin will have no effect on the reverse output

current when the output is pulled above the input.

INPUT VOLTAGE (V)

0

3

4

5

4

LT1529 • F04

2

1

0

1

2

3

5

LT1529-5

LT1529-3.3

Figure 4. Input Current

PACKAGE DESCRIPTIO

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tation that the interconnection of circuits as described herein will not infringe on existing patent rights.

Q Package

5-Lead Plastic DD Pak

(LTC DWG # 05-08-1461)

Q(DD5) 0502

.028 – .038

(0.711 – 0.965)

TYP

.143

+.012

–.020

()

3.632

+0.305

–0.508

.067

(1.702)

BSC

.013 – .023

(0.330 – 0.584)

.095 – .115

(2.413 – 2.921)

.004

+.008

–.004

()

0.102

+0.203

–0.102

.050 ± .012

(1.270 ± 0.305)

.059

(1.499)

TYP

.045 – .055

(1.143 – 1.397)

.165 – .180

(4.191 – 4.572)

.330 – .370

(8.382 – 9.398)

.060

(1.524)

TYP

.390 – .415

(9.906 – 10.541)

15° TYP

.325

.205

.080

.565

.090

RECOMMENDED SOLDER PAD LAYOUT

FOR THICKER SOLDER PASTE APPLICATIONS

.042

.067

.420

.276

.320

.420

.350

.565

.090

.042

.067

RECOMMENDED SOLDER PAD LAYOUT

NOTE:

1. DIMENSIONS IN INCH/(MILLIMETER)

2. DRAWING NOT TO SCALE

.300

(7.620)

.075

(1.905)

.183

(4.648)

.060

(1.524)

.060

(1.524)

.256

(6.502)

BOTTOM VIEW OF DD PAK

HATCHED AREA IS SOLDER PLATED

COPPER HEAT SINK