PT6880 Datasheet, PDF (6/8 Pages) Princeton Technology Corp – OLED Driver/Controller IC

Application Notes
PT6880 Series
Adjusting the Output Voltage of the PT6880
5-A Excalibur™ Converter Series
The output voltage of the Power Trends PT6880 Excalibur
series of ISRs may be adjusted higher or lower than the
factory trimmed pre-set voltage with the addition of a
single external resistor ¹. Table 3-1 gives the respective
allowable adjustment range for each model in the 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 1 (V_o Adjust) and
pins 6, 7 /11-14 (GND).
Adjust Down: Add a resistor (R₁), between pin 1 (V_o Ad-
just) and pins 15-17 (V_out).
Refer to Figure 3-1 and Table 3-2 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,
V_out, or the Remote Sense pin. Any capacitance added to
the V_o adjust pin will affect the stability of the ISR.
3. If the remote sense feature is being used, connecting the
resistor (R₁) between pin 1 (V_o Adjust) and pin 18 (Remote
Sense) can benefit load regulation.
4. For output voltages above 10Vdc, the maximum output
current must be limited to 4Adc.
5. Adjustments to the output voltage may place additional
limits on the input voltage for the part. The revised limits
must comply with the following requirements.
V_in (min)
= (V_out + 3)V or 15V,
whichever is higher.
V_in (max)
= (10 x V_out )V or 36V,
whichever is less.
Figure 3-1
18
Vsense
Vin
8 –10
Vin
PT6880
15 –17
Vo
+
C _in
STBY
4
GND
Vo(adj)
6, 7,
1
11 – 14
(R1)
Adj Down
R2
Adjust
Up
COM
+
C _out
Vo
L
O
A
D
COM
The values of (R₁) [adjust down], and R₂ [adjust up], can
also be calculated using the following formulas.
(R₁)
=
R_o (V_o – 1.25) (V_a – 1.25)
1.25 (V_o – V_a)
– R_s kΩ
R₂
=
R_o (V_o – 1.25)
V_a - V_o
– R_s
kΩ
Where:
V_o = Original output voltage
V_a = Adjusted output voltage
R_o = The resistance value in Table 3-1
R_s = The series resistance from Table 3-1
Table 3-1
PT6880 ADJUSTMENT AND FORMULA PARAMETERS
Series Pt #
PT6882
PT6881
Vo (nom)
2.5V
3.3V
V_a (min)
1.8V
2.2V
Va (max)
4.3V
4.7V
R_o (kΩ)
4.99
4.22
Rs (kΩ)
2.49
4.99
PT6883
5.0V
3.0V
6.5V
2.49
4.99
PT6884
9.0V
6.0V
10.2V
2.0
12.7
PT6886
12.0V
9.0V
13.6V
2.0
12.7
PT6885
15.0V
10.0V
17.0V
2.0
12.7
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