pth03010 Astec Powe, pth03010 Datasheet - Page 8

• Manufacturer Part Number: pth03010
• Description: Pth03020 3.3vin Single
• Manufacturer: Astec Powe

7. Feature Set
7.1 Adjusting the Output Voltage
The V
product. The adjustment range is from 0.8 Vdc to 2.5 Vdc. The
adjustment method requires the addition of a single external resistor,
R
GND pins
for a number of standard voltages, along with the actual output
voltage that this resistance value provides.
For other output voltages the value of the required resistor can either
be calculated using the following formula, or simply selected from
the range of values given in Table 5. Figure 8 shows the placement of
the required resistor.
Table 4 - Preferred Values of R
set
V
8 8
, that must be connected directly between the Vo Adjust and
out
o
adjust control (pin 4) sets the output voltage of the PTH03020
2.5 V
2.0 V
1.8 V
1.5 V
1.2 V
1.0 V
0.8 V
Standard
GND
(1)
10
1
. Table 4 gives the preferred value for the external resistor
PTH05020W
Figure 8 - Adjust Resistor Placement
GND
9
7
8
R SET
0.1 W, 1 %
R
set
(Preferred Value)
File Name: an_pth03020.pdf Rev (05): 21 Dec 2005
2.21 kΩ
4.12 kΩ
5.49 kΩ
8.87 kΩ
17.4 kΩ
36.5 kΩ
V
Open
o
set
V
o
Sense
Adj
for Standard Output Voltages
V
5
4
o
V
Sense (See Note 2)
out
6
C
330µF
out
V
out
2.502 V
2.010 V
1.803 V
1.504 V
1.202 V
1.005 V
+
0.8 V
(Actual)
GND
V
out
Notes:
1 Use a 0.1 W resistor, with a tolerance of 1% (or better). Place the
2 Never connect capacitors from V
7.2 Output ON/OFF Inhibit
For applications requiring output voltage ON/OFF control,each series
of the PTH family incorporates an output Inhibit control pin. The
inhibit feature can be used wherever there is a requirement for the
output voltage from the regulator to be turned OFF.
The power modules function normally when the Inhibit pin is left
open-circuit, providing a regulated output whenever a valid source
voltage is connected to V
typical application of the inhibit function. Note the discrete transistor
(Q1). The Inhibit control has its own internal pull-up to +Vin potential.
An open-collector or open-drain device is recommended to control
this input.
Turning Q1 on applies a low voltage to the Inhibit control pin and
disables the output of the module. If Q1 is then turned off, the
module will execute a soft-start power-up sequence. A regulated
output voltage is produced within 20 ms. Figure 10 shows the typical
rise in both the output voltage and input current, following the turn-
off of Q1. The turn off of Q1 corresponds to the rise in the waveform,
Q1 V
V
a
resistor as close to the regulator as possible. Connect the resistor
directly between pins 4 and 7 using dedicated PCB traces.
Any capacitance added to the V
of the regulator.
0.800
0.825
0.850
0.875
0.900
0.925
0.950
0.975
1.000
1.025
1.050
1.075
1.100
1.125
1.150
1.175
1.200
Req’d
DS
. The waveforms were measured with a 5 A load.
Table 5 - Output Voltage Set-point Resistor Values
OUTPUT VOLTAGE SET-POINT RESISTOR VALUES
77.5 kΩ
61.5 kΩ
50.8 kΩ
43.2 kΩ
37.5 kΩ
33.1 kΩ
29.5 kΩ
26.6 kΩ
24.2 kΩ
22.1 kΩ
20.4 kΩ
18.8 kΩ
17.5 kΩ
318 kΩ
158 kΩ
104 kΩ
Open
PTH03020 Single Series | Application Note 151
R
set
V
a
in
1.225
1.275
1.300
1.325
1.350
1.375
1.400
1.425
1.450
1.475
1.250
1.50
1.55
1.60
1.65
1.70
Req’d
with respect to GND. Figure 9 shows the
o
16.3 kΩ
15.3 kΩ
14.4 kΩ
13.5 kΩ
12.7 kΩ
12.1 kΩ
11.4 kΩ
10.8 kΩ
10.3 kΩ
9.82 kΩ
9.36 kΩ
8.94 kΩ
8.18 kΩ
7.51 kΩ
6.92 kΩ
o
6.4 kΩ
Adjust pin will affect the stability
Adjust to either GND or V
R
set
V
a
1.75
1.80
1.85
1.90
1.95
2.00
2.05
2.10
2.15
2.20
2.25
2.30
2.35
2.40
2.45
2.50
Req’d
5.93 kΩ
5.51 kΩ
5.13 kΩ
4.78 kΩ
4.47 kΩ
4.18 kΩ
3.91 kΩ
3.66 kΩ
3.44 kΩ
3.22 kΩ
3.03 kΩ
2.84 kΩ
2.67 kΩ
2.51 kΩ
2.36 kΩ
2.22 kΩ
R
out
set
.