Datasheet
11
LT1529
LT1529-3.3/LT1529-5
152935fb
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S
A
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PP
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AT
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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
output current also follows the curve in Figure 3 if the V
IN
pin is left open. The state of the SHDN pin will have no
effect on the reverse output current when the V
IN
pin is
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.
When the V
IN
pin is forced below the OUTPUT pin or the
OUTPUT pin is pulled above the V
IN
pin, the input current
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
INPUT CURRENT (µA)
3
4
5
4
LT1529 • F04
2
1
0
1
2
3
5
LT1529-5LT1529-3.3
V
OUT
= 3.3V (LT1529-3.3)
V
OUT
= 5V (LT1529-5)
Figure 4. Input Current
PACKAGE DESCRIPTIO
U
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