
Application Notes
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
PT6100/6210/6300 Series
Adjusting the Output Voltage of Power Trends’
Wide Input Range Bus ISRs
The output voltage of the Power Trends’ Wide Input
Range Series ISRs may be adjusted higher or lower than the
factory trimmed pre-set voltage with the addition of a single
external resistor. Table 1 accordingly gives the allowable
adjustment range for each model for either series as V
a (min)
and V
a (max).
Adjust Up:
An increase in the output voltage is obtained by
adding a resistor R2, between pin 12 (Vo adjust) and pins 5-8
(GND).
Adjust Down:
Add a resistor (R1), between pin 12 (Vo adjust)
and pins 9-11(Vout).
Refer to Figure 1 and Table 2 for both the placement and value
of the required resistor; either (R1) or R2 as appropriate.
Notes:
1. Use only a single 1% resistor in either the (R1) or R2
location. Place the resistor as close to the ISR as possible.
2. Never connect capacitors from V
o adjust to either GND or
V
out. Any capacitance added to the Vo adjust pin will affect
the stability of the ISR.
3. Adjustments to the output voltage may place additional
limits on the maximum and minimum input voltage for the
part. The revised maximum and minimum input voltage
limits must comply with the following requirements. Note
that the minimum input voltage limits are also model
dependant.
V
in (max)
= (8 x V
a)V or
*30/38V,
whichever is less.
*Limit is 30V when inhibit function is active.
PT6x0x/PT6x1x series:
V
in (min)
= (V
a + 4)V or 9V,
whichever is greater.
PT6x2x series:
V
o <10V;
V
in (min)
= (V
a + 2.0)V or 7.0V,
whichever is greater.
V
o
≥10V;
V
in (min)
= (V
a + 2.5)V
Figure 1
The values of (R1) [adjust down], and R2 [adjust up], can
also be calculated using the following formulae.
Ro (Va – 1.25)
(R1)
=
Vo – Va
k
1.25 Ro
k
R2
=
Va – Vo
Where: V
o
= Original output voltage
V
a
= Adjusted output voltage
R
o
= The resistance value fromTable 1
Table 1
ISR ADJUSTMENT RANGE AND FORMULA PARAMETERS
1Adc Rated
PT6102
PT6101
PT6103
2Adc Rated
PT6213
PT6212
PT6214
3Adc Rated
PT6303
PT6302
PT6304
Vo (nom)
3.3
5.0
12.0
Va (min)
1.89
1.88
2.18
2.43
Va (max)
6.07
11.25
8.5
22.12
Ro (k
)
66.5
150.0
90.9
243.0
R2
Adjust
Up
C1
1
F Ceramic
(Optional)
C2
100
F
(Req’d)
Vo
COM
Vin
+
(R1)
Adj Down
PT6100/6200/6300
9,10,11
12
5,6,7,8
2,3,4
Vin
Vo
G N D
Vo(adj)