Datasheet

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V =12V
I
V 1=3.3V
O
V 2=1.8V
O
R
SET
1
2.49kW
R
SET
2
16.9kW
R
TRK
50 W
R
RST
10kW
C
T
2.2 Fm
C
REF
0.1 Fm
C 1
O
C 2
O
C 1
I
C 2
I
+
U3
TL7712A
V
CC
GND
SENSE
RESIN
REF
CT
RESET
RESET
8
7
2
1
3
5
6
4
U1
U2
+
UVLOProg
Inhibit/
GND
Track
PTV08040W
PTV08040W
V
I
V
I
V
O
V
O
UVLOProg
Inhibit/
+Sense
+Sense
-Sense
-Sense
GND
Track
V
O
Adj
V
O
Adj
N/C
N/C
PTV08040W
SLTS257B – SEPTEMBER 2005 – REVISED JANUARY 2008
Notes on Use of Auto-Track™
1. The Track pin voltage must be allowed to rise above the module set-point voltage before the module
regulates at its adjusted set-point voltage.
2. The Auto-Track function tracks almost any voltage ramp during power up, and is compatible with ramp
speeds of up to 1 V/ms.
3. The absolute maximum voltage that may be applied to the Track pin is the input voltage V
I
.
4. The module cannot follow a voltage at its track control input until it has completed its soft-start initialization.
This takes about 20 ms from the time that a valid voltage has been applied to its input. During this period, it
is recommended that the Track pin be held at ground potential.
5. The Auto-Track function is disabled by connecting the Track pin to the input voltage (V
I
). When Auto-Track is
disabled, the output voltage rises at a quicker and more linear rate after input power has been applied.
Figure 15. Sequenced Power Up and Power Down Using Auto-Track
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