PTB48520W Datasheet, PDF (13/18 Pages) Texas Instruments – 25-A, 48-V INPUT ISOLATED DC/DC CONVERTER WITH AUTO-TRACK™ SEQUENCING

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U1
4
Track
PTB48520W
8
+Sense
10
+V_I
1
V_OSeq
+V_I
9
V_OBus
2
7
V_OEnable _VOAdjust
5
V_OCOM
−V_I
3
−V_I
6
−Sense
R1
887 W
PTB48520W
SLTS233A – NOVEMBER 2004 – REVISED APRIL 2005
U2
3 _VI
2
Track
PTH03050W
6
V_O
Inhibit
4
C1
100 mF
GND Adjust
15
R2
2.21 kW
U3
3
V_I
2
Track
PTH03050W
6
V_O
Inhibit
4
C2
100 mF
GND Adjust
15
R3
5.49 kW
V_OSEQ (3.3 V)
V_(POL)1 (2.5 V)
C3
100 mF
V_(POL)2 (1.8 V)
C4
100 mF
Figure 10. Power-Up Sequencing With Non-Isolated POL Modules
Stand-Alone Operation
The wide output voltage adjust range makes the PTB48520W an attractive product as a stand-alone dc/dc
converter. In these applications, it is not required to power up or sequence with any non-isolated POL modules.
The output voltage can be adjusted to any value over the range, 1.8 V to 3.6 V, and the Auto-Track features
simply disregarded.
Figure 11 shows the recommended configuration when the module is used as a stand-alone converter. In this
case, a sequenced output voltage is not required, and the main output (V_O Bus) can be used to supply the load.
Both the Track pin and the V_O Seq output are simply left open circuit. The (+)Sense pin is connected to the V_O
Bus output for improved load regulation.
When the converter is operated in this mode, the output from V_O Bus rises promptly on power up. The converter
also exhibits slightly less power dissipation along with a corresponding improvement in operating efficiency.
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