PT6674 Datasheet, PDF (3/5 Pages) Texas Instruments – 5V/3.3V Input 20W Boost Integrated Switching Regulator

Application Notes
PT6670 Series
Adjusting the Output Voltage of the PT6670
Series Boost Voltage ISR
The Power Trends PT6670 ISRs are a series of convert-
ers that operate from a 3.3V or 5V input bus voltage. In
each case, the output voltage can be adjusted higher or
lower than the factory trimmed pre-set voltage. Adjust-
ment requires the addition of a single external resistor.
Table 1 gives the permissible adjustment range for each
model in the series as V_a(min) and V_a(max) respectively.
Adjust Up:
To increase the output, add a resistor
R2 between pin 14 (V_o Adjust) and pins 7-10 (GND).
Adjust Down:
Add a resistor (R1), between pin 14
(V_o Adjust) and pin 1 (Remote Sense).
Refer to Figure 1 and Table 2 for both the placement and value
of the required resistor.
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. Do not exceed the maximum advised adjustment voltage.
Doing so could over stress the part.
3. Never connect capacitors to the V_o Adjust control pin. Any
capacitance added to this pin will affect the stability of the
ISR.
4. In the case of the PT6671, when the output is adjusted
lower than the pre-trimmed output, the maximum input
voltage to the ISR should not exceed (V₀ – 0.5)V.
The adjust up and adjust down resistor values can also be
calculated using the following formulas. Be sure to select
the correct formula parameters from Table 1 for the model
being adjusted.
(R1)
= ^{Ko (Va – 2.5)}
2.5 (V_o – V_a)
– R_s kΩ
R2
=
K_o
V_a – V_o
– R_s kΩ
Where:
V_o = Original output voltage
V_a = Adjusted output voltage
K_o = The multiplier constant in Table 1
R_s = The series resistance from Table 1
Figure 1
Vin
4,5,6 _Vin
+
C _in
1
Vsense
PT6670
Vo ^11,12,13
GND
Vo(adj)
7,8,9,10 14
(R1)
Adj Down
R2
Adjust
Up
+
C _out
Vo
L
O
A
D
COM
COM
Table 1
PT6670 ADJUSTMENT RANGE AND FORMULA PARAMETERS
Series Pt #
3.3V Bus
PT6671
PT6672
PT6673
5.0V Bus
PT6675
PT6674
Vo(nom)
Va(min)
Va(max)
Ko (V·kΩ)
Rs (kΩ)
5.0V
3.8V
5.5V
25.0
4.99
9.0V
8.2V
9.2V
48.75
80.6
12.0V
9.6V
12.8V
47.41
54.9
Table 2
PT6670 ADJUSTMENT RESISTOR VALUES
Series Pt #
3.3V Bus PT6671
5.0V Bus
Vo(nom)
Va(req’d)
3.8
3.9
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5.0
5.1
5.2
5.3
5.4
5.5
5.0V
(5.8)kΩ
(7.7)kΩ
(10.0kΩ
(12.8)kΩ
(16.3)kΩ
(20.7)kΩ
(26.7)kΩ
(35.0)kΩ
(47.5)kΩ
(68.3)kΩ
(110.0)kΩ
(235.0)kΩ
245.0kΩ
120.0kΩ
78.3kΩ
57.5kΩ
45.0kΩ
Va(req’d)
8.2
8.4
8.6
8.8
9.0
9.2
9.4
9.6
9.8
10.0
10.2
10.4
10.6
10.8
11.0
11.2
11.4
11.6
11.8
12.0
12.2
12.4
12.6
12.8
R1 = (Blue)
R2 = Black
PT6672
PT6675
9.0V
(58.3)kΩ
(111.0)kΩ
(217.0)kΩ
(534.0)kΩ
163.0kΩ
PT6673
PT6674
12.0V
(1.2)kΩ
(8.0)kΩ
(16.2)kΩ
(26.2)kΩ
(38.7)kΩ
(54.8)kΩ
(76.3)kΩ
(106.0)kΩ
(151.0)kΩ
(226.0)kΩ
(376.0)kΩ
(827.0)kΩ
182.0kΩ
63.3kΩ
24.1kΩ
4.4kΩ
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