Texas Instruments ADS1282V2EVM-PDK User Manual page 9

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2.8 Low Dropout Regulators (LDO)
Figure 2-8 shows how the ADS1282 5.3V AVDD and -2.5V AVSS supplies are generated. The PHI provides
power for AVDD. The user must apply an external power supply to generate the -2.5V rail for AVSS.
The TPS7A47-Q1 LDO regulates AVDD to 5.3V. The 5.3V LDO output is used for the AVDD connections and
can be reprogrammed to different output voltages using R46, R47, R48, R49, R50, and R51. See
possible configurations.
The TPS7A30 LDO generates the -2.5V rail for AVSS. This LDO is only supplied by external power on header
J6. By default, AVSS is connected to GND with a shunt on jumper JP1, position 1-2. If AVSS is set to -2.5V for
bipolar operation, connect an external negative supply to J6 and move the shunt on jumper JP2 to position 2-3.
In this configuration, the voltage level for AVDD does not need to be changed. The 5.3V LDO is referenced to
AVSS, so setting AVSS = -2.5V also changes AVDD to 2.8V with respect to GND.
Remove R42 to measure LDO
input current using external
ammeter
J6
-Vin
2
-5V ≤ -Vin ≤ -3V
DNP
1
GND
Remove R38 to measure LDO
input current using external
ammeter
TP5
+5.5V
5.5V
R38
0
C19
10µF
AVSS
R46 R47
DNP DNP
0 0
SBAU431 – JULY 2024
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TP7
-2.5V
GND
GND U5
R42
8
IN
0
C22
5
EN
10µF
6
NR/SS
7
DNC
C25
0.01 µF
3
NC
TPS7A3001DRBR
GND GND GND
AVDD
U4
+5.5V
15
IN
16
IN
R41
13
EN
82k
4
6P4V2
5
6P4V1
6
3P2V
8
1P6V
9
0P8V
10
0P4V
11
0P2V
12
0P1V
TPS7A4701QRGWRQ1
R48 R49 R50 R51
0 0 0 0
AVSS
Figure 2-8. LDO Regulators: -2.5V (top), 5.3V (bottom)
Copyright © 2024 Texas Instruments Incorporated
Remove R43 to measure -2.5V
rail current using external
ammeter
TP8
-2.5V
R43
1
OUT
0
R44
11.3k C23
0.01 µF
2
FB
R45
10.0k
4
GND
9
PAD
GND
Remove R39 to measure
AVDD current using external
ammeter
R39
1
OUT
20
0
OUT
3
SENSE/FB
14
NR
19
NC
18
NC
C21
17
NC
1µF
2
NC
AVSS
7
GND
21
PAD
AVSS
Section 5.1
-2.5V
C24
10µF
GND
TP6
AVDD(5.3)
AVDD(5.3)
Unipolar: 5.3V to GND
Bipolar: 5.3V to AVSS
R40
2.0k
C20
10µF
D1
Green AVSS
ADS1282EVM-PDK Evaluation Module
Hardware
for
9