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Configuration

Note 1: output voltage

Voltage references:
REF102: 10V
REF02: 5V (omit C44 with REF02)

Please note: R15, R16 and R17 have to be of the same value. If you alter R15 from 10k then you have to alter R16 and R17, too. 10k is default and recommended.

output voltage determined by VoltageReference, R20 and R15:

Uout= Uref * ( 1 + (R20/R15) ) V
 = 10 * ( 1 + (6200 / 10000) ) V
 = 16.2 V
R20 Ω   R15 Ω   VREF   output V

 

determine R20 for given VoltageReference and target output voltage:

R20= ( Uout / Uref ) - 1 ) * R15 Ω
 = ( 16.2 / 10 ) - 1 ) * 10000 Ω
 = 6200 Ω
UOUT V   R15 Ω   VREF     R20 Ω

 

Note 2: Voltage drops across stages

output voltage of preregulator stage, voltage drops across stages

  • configure voltage drop across the voltage regulator to at least 3V (target range: 3V to 5V)
  • output voltages of the opamps should be at least 5V below the rail voltages (target range: 6V to 7V, max: 8V)
  • adjust output voltages of the regulators accordingly, using trimpots R18 and R19
Uout (target)
=Uout_opamp
R20 Transformer Urectified
= Ureg_in
drop across
regulator
Ureg_out
= VCC OpAmp
drop across
opamp
V_out_+ : GND   IN_1_a : IN_1_b TP1 : GND TP1 : TP2 TP2 : GND TP2 : V_out_+
GND : V_out_-   IN_2_a : IN_2_b TP3 : TP4 TP4 : V_out_- GND : TP4 TP4 : V_out_-

±20V

10kΩ

2× 22 VAC

29,6 VDC

3,0 VDC

26,6 VDC

6,6 VDC

±18V

8kΩ

2× 22 VAC

29,6 VDC

4,0 VDC

25,6 VDC

7,6 VDC

±16V

6kΩ

2× 22 VAC

29,6 VDC

5,5 VDC

24,1 VDC

8,1 VDC

±16V

6kΩ

2× 18 VAC

24,0 VDC

3,0 VDC

21,0 VDC

5,0 VDC

±15V

5kΩ

2× 18 VAC

24,0 VDC

3,0 VDC

21,0 VDC

6,0 VDC

±12V

2kΩ

2× 18 VAC

24,0 VDC

4,0 VDC

20,0 VDC

8,0 VDC

±12V

2kΩ

2× 15 VAC

19,7 VDC

2,7 VDC

16,7 VDC

5,0 VDC

When using a transformer with more than 18VAC secondaries then select capacitors (particulary electrolytic and tantalum) with a voltage rating of at least 50V instead of 35V.

resistor precision, thermal drift, fine tuning

  • VoltageReference adjustment with optional trimpot (pin5 of REF102(trim out), fine tuning, temperature compensation)
  • R15 / R16 / R17/ R20 ... precision, thermal drift

Note 3: current rating

  • max current limited by: inductor in the output path (up to 1.2A) / LM317 (1.5A) / OPA544 (2.0A)
  • max continuous current: about 1A

Note 4: heat dissipation

  • voltage drop across LM317 × current draw = dissipated heat from the regulator
    recommended drop: between 3V and 5V
  • voltage drop across OPA544 × current draw = dissipated heat from the opamp
    recommended drop: between 5V and 7V
  • dissipated heat × 4K/W (heatsink) = temperature rise of the heatsink above ambient temperature
Voltage drop
[V]
current draw
[mA]
  heat dissipation
[W]
temp rise of heatsink
above ambient temp
[°C]
junction temp
at 25C ambient temp
[°C]