259481A Marking, TPS259481AYWPR datasheet(44/56 Pages) TI

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9.8 Power Supply Recommendations

The TPS25948x devices are designed for a supply voltage range of 3.5 V ≤ VIN or VOUT ≤ 23 V. An input ceramic

bypass capacitor higher than 0.1 μF is recommended if the input supply is located more than a few inches from

the device. The power supply must be rated higher than the set current limit to avoid voltage droops during

overcurrent and short-circuit conditions.

9.8.1 Transient Protection

In the case of a short-circuit and overload current limit when the device interrupts current flow, the input

inductance generates a positive voltage spike on the input, and the output inductance generates a negative

voltage spike on the output. The peak amplitude of voltage spikes (transients) is dependent on the value of

inductance in series to the input or output of the device. Such transients can exceed the absolute maximum

ratings of the device if steps are not taken to address the issue. Typical methods for addressing transients

include:

• Minimize lead length and inductance into and out of the device.

• Use a large PCB GND plane.

• Connect a Schottky diode from the OUT pin ground to absorb negative spikes.

• Connect a low ESR capacitor larger than 1 μF at the OUT pin very close to the device.

• Use a low-value ceramic capacitor CIN = 1 μF to absorb the energy and dampen the transients. The capacitor

voltage rating should be atleast twice the input supply voltage to be able to withstand the positive voltage

excursion during inductive ringing.

The approximate value of input capacitance can be estimated with the equation:

VSPIKE(ABSOLUTE) = VIN +ILOAD × LINCIN

(19)

where

– VIN is the nominal supply voltage.

– • ILOAD is the load current.

– LIN equals the effective inductance seen looking into the source.

– CIN is the capacitance present at the input.

• Some applications may require the addition of a Transient Voltage Suppressor (TVS) to prevent transients

from exceeding the absolute maximum ratings of the device. In some cases, even if the maximum amplitude

of the transients is below the absolute maximum rating of the device, a TVS can help to absorb the excessive

energy dump and prevent it from creating very fast transient voltages on the input supply pin of the IC, which

can couple to the internal control circuits and cause unexpected behavior.

• For applications such as USB-C ports where a powered cable can be plugged to the output of the device,

there could be excess voltage stress from OUT to IN which exceeds the absolute maximum rating of the

device. It's recommended to add a TVS diode from OUT to IN to clamp the voltage to a safe level.

The circuit implementation with optional protection components is shown in Figure 9-23.

TPS259480x

OUT

EN/UVLO

ILM

dVdt

GND

IN = 3.5 to 23 V

ILM

OUT

OVLO

SPLYGD

FLT

ITIMER

DVDT

ITIMER

Figure 9-23. Circuit Implementation with Optional Protection Components

TPS25948

SLVSGT9A – FEBRUARY 2023 – REVISED SEPTEMBER 2023

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