Datasheet

Power
Supply
#1
Power
Supply
#2
RL
Power
Supply
#1
Power
Supply
#2
RL
VVV
AAA
AAA
VVV
VVV
OUT
R1
V 0.9 1
R2
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= ´ +
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Operation www.ti.com
3.2 Connection Setup
1. 1 Connect power supply #1 to V
IN
(J3) and its return connection to J5 as shown in Figure 2. V
IN
should
be at least 300mV (or V
DO
) greater than V
OUT
, up to 5.5V.
2. Connect power supply #2 to V
BIAS
(J1) and its return connection to J2 as shown in Figure 2. V
BIAS
must
be between 3.0V and 5.5V.
3. An ammeter can be connected in series with either power supply to measure the supply current or bias
current.
4. For TPS74012DPT (fixed voltage part), attach a jumper on JP1 shorting EN and V
IN
(ties EN high).
5. If desired, a load can be connected at the output, J4 and J6.
6. Connect a voltmeter or an oscilloscope voltage probe across the output pins J4 and J6 to observe and
measure the regulated output voltage.
Figure 2. Quick Start Connection Setup
4 Operation
This section provides information about the operation of the TPS740xxDPTEVM and expected outputs.
The TPS740xx parts can support input voltages (V
IN
) between 1.2V and 5.5V and output voltages (V
OUT
)
between 0.9V and 4.0V. A separate V
BIAS
input supply (3.0V to 5.5V) 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 2.2µF (minimum) to ensure stability of the IC.
4.1 Adjustable Output Voltage
TPS74001DPT EVM comes configured for a 1.5V output voltage. However, this output voltage can easily
be modified to range between 0.9V and 4.0V 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 4.99kΩ. 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.
4
TPS740xxDPTEVM-713 Evaluation Module SLVU476– June 2011
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