TPS259250 Datasheet, PDF (23/35 Pages) Texas Instruments – Simple 5V/12V eFuse Protection Switches

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TPS259250, TPS259251, TPS259260, TPS259261
SLVSCQ3A – AUGUST 2015 – REVISED AUGUST 2015
10 Power Supply Recommendations
The device is designed for supply voltage range of 4.5 V ≤ V_IN ≤ 18 V. If the input supply is located more than a
few inches from the device an input ceramic bypass capacitor higher than 0.1 μF is recommended. Power supply
should be rated higher than the current limit set to avoid voltage droops during over current and short-circuit
conditions.
10.1 Transient Protection
In case of short circuit and over load current limit, when the device interrupts current flow, input inductance
generates a positive voltage spike on the input and output inductance generates a negative voltage spike on the
output. The peak amplitude of voltage spikes (transients) is dependent on 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:
• Minimizing lead length and inductance into and out of the device
• Using large PCB GND plane
• Schottky diode across the output to absorb negative spikes
• A low value ceramic capacitor (C_(IN) = 0.001 µF to 0.1 µF) to absorb the energy and dampen the transients.
The approximate value of input capacitance can be estimated with Equation 18:
V_{SPIKE(Absolute)} = V_(IN) + I_(LOAD) x
L_(IN)
C_(IN)
(18)
Where:
• V_(IN) is the nominal supply voltage
• I_(LOAD) is the load current
• L_(IN) equals the effective inductance seen looking into the source
• C_(IN) 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.
The circuit implementation with optional protection components (a ceramic capacitor, TVS and schottky diode) is
shown in Figure 46.
IN 4.5 to 18 V
IN
OUT
(Note 1)
C_IN
30mO
(Note 1)
EN/UVLO
OUT
(Note 1)
dV/dT
ILIM
GND _TPS25925x/6x
(1) Optional components needed for suppression of transients
Figure 46. Circuit Implementation with Optional Protection Components
Copyright © 2015, Texas Instruments Incorporated
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