Datasheet

V
V
A
Power
Supply
#1
V
A
RL
Power
Supply
#2
OUT
R1
V 0.9 1
R2
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= ´ +
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Operation www.ti.com
Figure 2. Quick-Start Connection Setup
4 Operation
This section provides information about the operation of the TPS740xxDGK EVM and expected outputs.
The TPS740xx parts can support input voltages (V
IN
) between 1.2 V and 5.5 V and output voltages (V
OUT
)
between 0.9 V and 4 V. A separate V
BIAS
input supply (3 V to 5.5 V) powers the error amplifier, reference,
and internal control circuits to allow for very low main input supply voltage. The TPS740xx requires only a
small output ceramic capacitor of 2.2 µF (minimum) to ensure stability of the IC.
4.1 Adjustable Output Voltage
TPS74001DGK EVM comes configured for a 1.5-V output voltage. However, this output voltage can easily
be modified to range between 0.9 V and 4 V by changing the values of the resistors R
1
and R
2
that form a
voltage divider at the output of the IC. In order to achieve maximum accuracy, R
2
is recommended to be
lower than 4.99 kΩ. Proper values for R
1
and R
2
for a desired V
OUT
can be calculated using:
(1)
Sample resistor values of common output voltages are shown in Table 2.
Table 2. Sample Resistor Values for Common Output Voltages for
TPS74001DGK
R
1
[kΩ] R
2
[kΩ] VOUT [V]
Short Open 0.9
0.562 5.11 1
0.75 4.53 1.05
4
TPS740xxDGKEVM-722 Evaluation Module SLVU475A–June 2011–Revised June 2011
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