Texas Instruments TPS769 Series, Руководство пользователя, Страница: 8 / 25

Introduction
1-2 Introduction
1.1 Introduction
Low cost and simplicity of design make LDO regulators popular solutions in
low-power step-down applications where lack of isolation from the input
source is not a concern.
Applications of the EVM include single DSP C5400 device, digital camera,
medical test equipment, cell phones, consumer audio equipment, and battery
backup electronics.
Figure 1–1 shows the schematic of the TPS76901EVM-127 configured for a
1-V output. The TPS76933EVM–127 (3.3 V) schematic is shown in
Figure 1–2. The LDO utilizes a PMOS pass element, which reduces the device
quiescient current to 28
µ
A (max). Other features of the PMOS LDO is the low
dropout voltage of 71 mV (typ), thermal protection, over current limit, and 2
µ
A
shutdown quiescient current.
Figure 1–1. Schematic Diagram (TPS76901EVM-127, V
O
= 1 V)
J2
GND
R2/C2
0
C1
TL431CPK
U2
R1
Open
R5
J1
IN
(3 – 6 V)
C4
C3
+
Vfb
R6
R3
J3
OUT
Back-side
Components
R4
Open
4
5
EN
GND
IN
1
2
3
OUT
NC/FB
U1
TPS76901
1.3 k
Ω
0.001
µ
F
VREF = 2.495 V
IREF
130 k
Ω
1
µ
F 4.7
µ
F
19.1 k
Ω
The basic functionality of the EVM is to provide output voltages of 0 V to
5.5 V.
By means of external resistors and a voltage reference (R1–R6 and U1), the
output voltage is adjusted to provide an output voltage that is either above or
below the TPS76901 nominal, internal reference voltage of 1.224 V (V
FB
).