Datasheet

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APPLICATION INFORMATION

Input Capacitor

Output Capacitor

TPS70845, TPS70848

TPS70851, TPS70858

TPS70802

SLVS301D – JUNE 2000 – REVISED DECEMBER 2007

For a typical application, an input bypass capacitor (0.1 µ F to 1 µ F) is recommended. This capacitor will filter any

high frequency noise generated in the line. For fast transient conditions where droop at the input of the LDO may

occur because of high inrush current, it is recommended to place a larger capacitor at the input as well. The size

of this capacitor depends on the output current and response time of the main power supply, as well as the

distance to the V

pins of the LDO.

As with most LDO regulators, the TPS708xx requires an output capacitor connected between OUT and GND to

stabilize the internal control loop. The minimum recommended capacitance values are 10- µ F ceramic capacitors

with an ESR (equivalent series resistance) between 50-m Ω and 2.5- Ω or 6.8- µ F tantalum capacitors with ESR

between 250 m Ω and 4 Ω . Solid tantalum electrolytic, aluminum electrolytic, and multilayer ceramic capacitors

with capacitance values greater than 10 µ F are all suitable, provided they meet the requirements described

above. Larger capacitors provide a wider range of stability and better load transient response. Table 1 gives a

partial listing of surface-mount capacitors suitable for use with the TPS708xx for fast transient response

application.

This information, along with the ESR graphs, is included to assist in selection of suitable capacitance for user

applications. When necessary to achieve low height requirements along with high output current and/or high load

capacitance, several higher ESR capacitors can be used in parallel to meet the guidelines above.

Table 1. Partial Listing of TPS708xx-Compatible Surface-Mount Capacitors

VALUE MANUFACTURER MAX ESR MFR PART NO.

22 µ F Kemet 345 m Ω 7495C226K0010AS

33 µ F Sanyo 100 m Ω 10TPA33M

47 µ F Sanyo 100 m Ω 6TPA47M

68 µ F Sanyo 45 m Ω 10TPC68M