Evm Dc Voltage Setup; Trf4900 Evm Dc Voltage Setup - Texas Instruments TRF4900 User Manual

2.3 EVM DC Voltage Setup

The evaluation board should be used with a dc power supply voltage of 8 V
nominal. Figure 2−1 details the dc voltage supply setup for the TRF4900 EVM.
Figure 2−1. TRF4900 EVM DC Voltage Setup
V out for LM317 voltage regulator is equal to:
Vout = 1.25(1+((R32+R34)/R31))
V at terminal 3 of LM317 should be 2 V to 3 V
higher than V out
With V equal to 8 V,
in
V = 7.2 V
POWER
8.0V
RED
V in is equal to 8 V
nominal.
GROUND CLIPS
TP2 TP3 TP4
2-10
VR1
LM317MDT
CR5
3
VIN VOUT
S1JB
ADJ
C15
ZR1 C16
0.1 µ F
10µ F 1
SMBJ8.5CA
2
3
VR2
1
VI NC
2
VO VO
3 VO
VO
4
NC
ADJ
LM317LBD
R36
360 Ω
2
JP4
R31 C17 C18 C19
0.1 µ F
360 Ω 1µ F 0.01µ F
R32
500 Ω
220 Ω
R34
220 Ω
V adj Used to Change
V out From 2.2 V to 3.6 V
8
7
6
5
R35
C20
C21 C22
220 Ω
0.1 µ F
1µ F 0.01µ F
2.0 − 3.8 V (3.0 V TYP)
VCC1
0
LED3
VCC
LN1271R−(TR)
R33
3.3V
VCC2