Datasheet

Notes on Use of Auto-Track™
C
O1
V
O1
2.5 V
UDG-08150
+Sense
V
O
-Sense
V
O
R
SET1
GND
PTH08T210W
V
I
V
I
AutoTrack TurboTrans
C
I1
+
R
TT1
C
I2
GND
+
+
RESET
GND
5
6
4
SENSE7
RESIN
2
REF1
8
V
CC
CT3
RESET
U3
TL7712A
C
REF
0.1 mF
C
T
2.2 mF
R
RESET
10 kW
C
O2
V
O2
5.0 V
+Sense
V
O
-Sense
V
O
U2
PTH08T255W
V
I
V
I
V
I
V
I
AutoTrack TurboTrans
R
TT2
GND
+
V
I
12 V
V
O
Adj
GND GND GND
AGND
R
SET2
GND GND GND GND
V
O
Adj
(1)
100 kW
PTH08T255W
www.ti.com ........................................................................................................................................................................................... SLTS290 – NOVEMBER 2008
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 according to its softstart rate after input power has been applied.
6. The Auto-Track pin should never be used to regulate the module's output voltage for long-term, steady-state
operation.
(1) When using Auto-Track with the PTH08T255W, a 100-k Ω resistor must be placed between the V
I
and
AutoTrack pins.
Figure 15. Sequenced Power Up and Power Down Using Auto-Track
Copyright © 2008, Texas Instruments Incorporated 21
Product Folder Link(s): PTH08T255W