TL5209_15 Datasheet, PDF (13/23 Pages) Texas Instruments – TL5209 500-mA Low-Noise Low-Dropout Voltage Regulator With Shutdown

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9 Application and Implementation
TL5209
SLVS581B – SEPTEMBER 2006 – REVISED JUNE 2015
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
9.1.1 Low-Voltage Operation
When using the TL5209 in voltage-sensitive applications, special considerations are required. If appropriate
output and bypass capacitors are not chosen properly, these devices may experience a temporary overshoot of
their nominal voltages.
At start-up, the full input voltage is initially applied across the regulator pass transistor, causing it to be
temporarily fully turned on. By contrast, the error amplifier and voltage-reference circuits, being powered from the
output, are not powered up as fast. To slow down the output ramp and give the error amplifier time to respond,
select larger values of output and bypass capacitors. The longer ramp time of the output allows the regulator
enough time to respond and keeps the output from overshooting its nominal value.
To prevent an overshoot when starting up into a light load (≉100 μA), TI recommends 4.7-μF and 470-pF
capacitors for the output and bypass capacitors, respectively. At higher loads, 10-μF and 470-pF capacitors
should be used.
If the application is not very sensitive to regulator overshoot, both the output capacitor and bypass capacitor (if
applicable) can be reduced.
9.2 Typical Application
V_IN
1 µF
IN
OUT
EN
ADJ/BYP
GND
R1
470 pF
R2
V_OUT
2.2 µF
A. V_OUT = 1.242 V (1 + R2/R1)
B. R2 should be ≤ 470 kΩ for optimal performance.
C. Maximum V_OUT = 6.75 V ± 10%
Figure 40. TL5209 Typical Application
9.2.1 Design Requirements
For this design example, use the parameters listed in Table 2 as the input parameters.
DESIGN PARAMETER
V_IN
R1
Load current
Desired V_OUT
Table 2. Design Parameters
EXAMPLE VALUE
5V
100 kΩ
500 mA
3.3 V
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