TLVM13640 datasheet(33/43 Pages) TI2

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9 Power Supply Recommendations

The TLVM13630 buck module is designed to operate over a wide input voltage range of 3 V to 36 V. The

characteristics of the input supply must be compatible with the Absolute Maximum Ratings and Recommended

Operating Conditions in this data sheet. In addition, the input supply must be capable of delivering the required

input current to the loaded regulator circuit. Estimate the average input current with Equation 10.

OUT

(10)

where

• η = efficiency

If the module is connected to an input supply through long wires or PCB traces with a large impedance, take

special care to achieve stable performance. The parasitic inductance and resistance of the input cables can

have an adverse affect on module operation. More specifically, the parasitic inductance in combination with the

low-ESR ceramic input capacitors form an underdamped resonant circuit, possibly resulting in instability, voltage

transients, or both, each time the input supply is cycled ON and OFF. The parasitic resistance causes the input

voltage to dip during a load transient. If the module is operating close to the minimum input voltage, this dip can

cause false UVLO triggering and a system reset.

The best way to solve such issues is to reduce the distance from the input supply to the module and use an

electrolytic input capacitor in parallel with the ceramics. The moderate ESR of the electrolytic capacitor helps

damp the input resonant circuit and reduce any overshoot or undershoot at the input. A capacitance in the range

of 47 μF to 100 μF is usually sufficient to provide input parallel damping and helps hold the input voltage steady

during large load transients. A typical ESR of 0.1 Ω to 0.4 Ω provides enough damping for most input circuit

configurations.

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TLVM13630

SLVSFT6B – MAY 2021 – REVISED JANUARY 2022

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TLVM13640 Datasheet(PDF) 33 Page - Texas Instruments