PTH12030W/L
www.ti.com
SLTS211F–MAY 2003–REVISED FEBRUARY 2007
10
9
8
5
Up Dn Track
Sense
VI = 12 V
VO1 = 3.3 V
2
6
VI
VO
PTH12020W
Inhibit
3
GND
1
Adjust
+
C2
330 mF
7
4
+
R1
2 kW
C1
330 mF
10
9
8
5
Track
Sense
VO2 = 1.8 V
+
2
6
VO
VI
PTH12010L
GND
R3
11 k0
Inhibit
3
Vadj
4
TL7702B
8
IO2
1
7
VCC
7
SENSE
R2
130 W
5
6
VCCIO
VCORE
RESET
2
1
3
RESIN
REF
+
+
C3
330 mF
C4
330 mF
RESET
ASIC
CT
GND
4
R4
100 kW
R5
10 k0
C5
0.1 mF
C6
0.68 mF
Figure 19. Application Circuit Demonstrating Prebias Startup
MARGIN UP/DOWN CONTROLS
The PTH12060, PTH12010, PTH12020, and PTH12030 products incorporate Margin Up and Margin Down
control inputs. These controls allow the output voltage to be momentarily adjusted[1], either up or down, by a
nominal 5%. This provides a convenient method for dynamically testing the operation of the load circuit over its
supply margin or range. It can also be used to verify the function of supply voltage supervisors. The ±5% change
is applied to the adjusted output voltage, as set by the external resistor, RSET at the VO Adjust pin.
The 5% adjustment is made by pulling the appropriate margin control input directly to the GND terminal.[2]
A
low-leakage open-drain device, such as an n-channel MOSFET or p-channel JFET is recommended for this
purpose.[3] Adjustments of less than 5% can also be accommodated by adding series resistors to the control
inputs. The value of the resistor can be selected from Table 6, or calculated using the following formula.
MARGIN UP/DOWN ADJUST RESISTANCE CALCULATION
To reduce the margin adjustment to a value less than 5%, series resistors are required (See RD and RU in
Figure 20). For the same amount of adjustment, the resistor value calculated for RU and RD is the same. The
formula is as follows.
499
- 99.8 kW
RU or RD
=
D %
(2)
Where ∆% = The desired amount of margin adjust in percent.
19
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