Application Notes
ATH15T033 & ATH15T05 Series
Adjusting the Output Voltage of the ATH15T033
& ATH15T05 Wide-Output Adjust Power Modules
The
V
o
Adjust
control (pin 4) sets the output voltage of
the ATH15T033 and ATH15T05 products. The ad-
justment range of the ATH15T033 (3.3-V input) is from
0.8 V to 2.5 V
1
, and the ATH15T05 (5-V input) from
0.8 V to 3.6 V. The adjustment method requires the addi-
tion of a single external resistor, R
set
, that must be connected
directly between the
V
o
Adjust
and
GND
pins
2
. Table 1-1
gives the preferred value of the external resistor for a num-
ber 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 1-2.
Figure 1-1 shows the placement of the required resistor.
R
set
= 10 kΩ ·
0.8 V
V
out
– 0.8 V
– 2.49 kΩ
Table 1-2; Output Voltage Set-Point Resistor Values
V
a
Req’d
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
1.225
1.250
1.275
1.300
1.325
1.350
1.375
1.400
1.425
1.450
1.475
1.50
1.55
1.60
1.65
1.70
1.75
1.80
1.85
1.90
1.95
R
set
Open
318 kΩ
158 kΩ
104 kΩ
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
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
6.4 kΩ
5.93 kΩ
5.51 kΩ
5.13 kΩ
4.78 kΩ
4.47 kΩ
V
a
Req’d
2.00
2.05
2.10
2.15
2.20
2.25
2.30
2.35
2.40
2.45
2.50
2.55
2.60
2.65
2.70
2.75
2.80
2.85
2.90
2.95
3.00
3.05
3.10
3.15
3.20
3.25
3.30
3.35
3.40
3.45
3.50
3.55
3.60
R
set
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
2.08 kΩ
1.95 kΩ
1.83 kΩ
1.72 kΩ
1.61 kΩ
1.51 kΩ
1.41 kΩ
1.32 kΩ
1.23 kΩ
1.15 kΩ
1.07 kΩ
988
Ω
914
Ω
843
Ω
775
Ω
710
Ω
647
Ω
587
Ω
529
Ω
473
Ω
419
Ω
367
Ω
Table 1-1; Preferred Values of R
set
for Standard Output Voltages
V
out
(Standard)
3.3 V
1
2.5 V
2V
1.8 V
1.5 V
1.2 V
1V
0.8 V
R
set
(Pref’d Value)
698
Ω
2.21 kΩ
4.12 kΩ
5.49 kΩ
8.87 kΩ
17.4 kΩ
36.5 kΩ
Open
V
out
(Actual)
3.309V
2.502 V
2.010 V
1.803 V
1.504 V
1.202 V
1.005 V
0.8 V
Figure 1-1; V
o
Adjust Resistor Placement
V
O
Sense [Note 3]
10
9
8
5
V
O
Sense
ATH15T05-9J
PTH05010W
V
OUT
6
V
OUT
Notes:
1. Modules that operate from a 3.3-V input bus should
not be adjusted higher than 2.5 V.
2. Use a 0.1 W resistor. The tolerance should be 1 %, with
temperature stability of 100 ppm/°C (or better). Place
the resistor as close to the regulator as possible. Connect
the resistor directly between pins 4 and 7 using dedicated
PCB traces.
3. Never connect capacitors from
V
o
Adjust
to either
GND
or
V
out
. Any capacitance added to the
V
o
Adjust
pin will affect
the stability of the regulator.
GND
1
GND
7
V
O
Adj
4
R
SET
0.1 W, 1 %
C
OUT
330µF
North America (USA): 1-888-41-ASTEC
+
GND
Europe (UK): 44(1384)842-211
Asia (HK): 852-2437-9662
ASTEC [ Astec America, Inc ]
