Datasheet

TPS70345, TPS70348
TPS70351, TPS70358
TPS70302
SLVS285H –AUGUST 2000–REVISED APRIL 2010 www.ti.com
Input Capacitor
For a typical application, a ceramic input bypass capacitor (0.22 mF to 1 mF) is recommended to ensure device
stability. This capacitor should be as close as possible to the input pin. Because of the impedance of the input
supply, large transient currents cause the input voltage to droop. If this droop causes the input voltage to drop
below the UVLO threshold, the device turns off. Therefore, it is recommended that a larger capacitor be placed in
parallel with the ceramic bypass capacitor at the regulator input. The size of this capacitor depends on the output
current, response time of the main power supply, and the main power supply distance to the regulator. At a
minimum, the capacitor should be sized to ensure that the input voltage does not drop below the minimum UVLO
threshold voltage during normal operating conditions.
Output Capacitor
As with most LDO regulators, the TPS703xx requires an output capacitor connected between OUT and GND to
stabilize the internal control loop. The minimum recommended capacitance value for V
OUT1
is 22 mF and the ESR
(equivalent series resistance) must be between 50 mΩ and 800 mΩ. The minimum recommended capacitance
value for V
OUT2
is 47mF and the ESR must be between 50 mΩ and 2 Ω. Solid tantalum electrolytic, aluminum
electrolytic, and multilayer ceramic capacitors 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 TPS703xx for fast transient response
applications.
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 TPS703xx-Compatible Surface-Mount Capacitors
VALUE MANUFACTURER MFR PART NO.
680 mF Kemet T510X6871004AS
470 mF Sanyo 4TPB470M
150 mF Sanyo 4TPC150M
220 mF Sanyo 2R5TPC220M
100 mF Sanyo 6TPC100M
68 mF Sanyo 10TPC68M
68 mF Kemet T495D6861006AS
47 mF Kemet T495D4761010AS
33 mF Kemet T495C3361016AS
22 mF Kemet T495C2261010AS
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