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PT6500/PT6600 Series
A p p l i c a t i o n
N o t e s
More Application Notes
Figure 1
Adjusting the Output Voltage of the PT6500 and
PT6600 5V Bus Converters
1
The output voltage of the Power Trends PT6500/PT6600
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 in the series as Va (min) and Va (max).
Vo(sense)
4,5,6
11,12,13
Vo
Vin
PT6500/6600
Vo
Vin
STBY
G N D
Vo(adj)
3
7,8,9,10 14
(R1)
L
O
A
D
Adj Down
+
+
C in
330
C out
330
Adjust Up:
An increase in the output voltage is obtained by
µ
F
µF
adding a resistor R2, between pin 14 (Vo adjust) and pins 7-10
(GND).
R2
Adjust Up
Adjust Down: Add a resistor (R1), between pin 14 (Vo adjust)
and pins 11-13 (Vout).
COM
COM
The values of (R1) [adjust down], and R2 [adjust up], can
also be calculated using the following formulae.
Refer to Figure 1 and Table 2 for both the placement and value
of the required resistor, either (R1) or R2 as appropriate.
Notes:
Ro (Va – 1.0)
(Vo – Va)
(R1)
R2
=
=
– Rs kΩ
1. Use only a single 1% resistor in either the (R1) or R2 loca-
tion. Place the resistor as close to the ISR as possible.
2. Never connect capacitors from Vo adjust to either GND,
Ro
Va - Vo
Vout, or the Remote Sense pin. Any capacitance added to
– Rs
kΩ
the Vo adjust pin will affect the stability of the ISR.
3. If the Remote Sense feature is being used, connecting the
resistor (R1) between pin 14 (Vo adjust) and pin 1 (Remote
Sense) can benefit load regulation.
Where: Vo = Original output voltage
Va = Adjusted output voltage
Ro = The resistance value in Table 1
Rs = The series resistance from Table 1
4. The minimum input voltage required by the part is
Vout + 1.2 or 3.1V, whichever is higher.
Table 1
PT6500/6600 ADJUSTMENT AND FORMULA PARAMETERS
Series Pt #
PT6505
PT6507
PT6502
PT6508
PT6608
PT6506
PT6606
PT6503
PT6603
PT6501
PT6601
PT6504
PT6604
PT6605
PT6607
PT6602
V (nom)
1.2
1.3
1.5
1.7
1.8
2.5
3.3
2.25
4.2
3.6
2.5
o
V (min)
a
1.14
2.35
2.49
2.0
1.19
2.45
2.49
2.0
1.27
2.65
2.49
2.0
1.36
2.85
2.49
2.0
1.4
1.8
V (max)
a
2.95
2.49
2.0
3.5
4.3
R (kΩ)
o
4.99
4.22
12.1
12.1
10.0
12.1
R (kΩ)
s
3
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com