Datasheet
UG-056 Evaluation Board User Guide
Rev. B | Page 4 of 12
EVALUATION BOARD HARDWARE
EVALUATION BOARD CONFIGURATIONS
The ADP124/ADP125 evaluation boards are supplied with
different components, depending on the version that is ordered.
Components common to both versions are C1, C2, TP1, TP2,
and J1. Figure 4, Figure 5, and Figure 6 show the schematics
of the various ADP124 and ADP125 evaluation board
configurations. Table 1 describes the components.
The ADP125 is the same as the ADP124 except that the output
voltage dividers are internally disconnected and the feedback
input of the error amplifiers is brought out for each output. The
output voltage can be set using the following formula:
V
OUT
= 0.5 V(1 + R1/R2) + (ADJ
I-BIAS
)(R1)
The value of R1 should be less than 200 kΩ to minimize errors
in the output voltage caused by the ADJ pin input current. For
example, when R1 and R2 are equal to 200 kΩ, the output voltage
is 1.0 V. The output voltage error introduced by the ADJ pin input
current is 3 mV or 0.30%, assuming a typical ADJ pin input
current of 15 nA at 25°C.
1
2
3
8
7
6
5
08525-003
C1
TP2 TP1
C2
J1
V
IN
V
OUT
VIN
VIN
NC
EN
U1
VOUT
VOUT
VOUT
SENSE
GND
4
Figure 4. ADP124 MSOP Evaluation Board Schematic
1
2
3
8
7
6
5
08525-004
C1
TP2
TP3
TP1
C2
J1
V
IN
V
OUT
VIN
VIN
NC
EN
U1
VOUT
VOUT
ADJ
GND
4
R1
R2
Figure 5. ADP125 MSOP Evaluation Board Schematic
Table 1. Evaluation Board Hardware Components
Component Description
U1
1
ADP124/ADP125 low dropout linear regulators
C1 Input bypass capacitor, 1 μF, 0603 size
C2 Output capacitor, 1 μF, 0603 size
J1
Jumper (connects EN to VIN for automatic
startup)
TP1 Testpoint closer to VIN
TP2 Testpoint closer to VOUT
TP3
Testpoint closer to ADJ (ADP125 evaluation
board only)
R1, R2
0603 size feedback resistors between VOUT and
ADJ (ADP125 evaluation board only)
1
Component depends on evaluation board type ordered.
VOUT VIN
R1
C1
1µF
TP3
1
TP1
11
U1
ADP124/ADP125
VIN
8
VIN
7
NC
6
EN
5
GND
4
3
VSENSE/ADJ
VOUT
2
VOUT
1
J1
1-WAY LINK
12
C2
1µF
R2
TP2
08525-106
Figure 6. ADP124/ADP125 Evaluation Board Schematic, LFCSP