TPS22922 Load Switch: 7 Checks for Discharge and Inrush
TPS22922 Load Switch: 7 Checks for Discharge and Inrush
Select TPS22922 power switching with seven checks for the 3.6-volt limit, active-high control, suffix rise time, output discharge and capacitive-load startup. This is a documentation-based planning guide, not a report of independent hands-on testing.
1. Verify the voltage class before selecting the family
TPS22922 operates from 0.9 V to 3.6 V. It is not a 5 V load switch simply because other TPS229xx devices support that rail. Check supply tolerance and transients against the complete pin ratings before connecting a nominal battery or regulator. The shared datasheet includes TPS22921 and TPS22922B with meaningful functional differences. Record the complete device, package and pitch; similarly named wafer-scale packages should not be assumed to share an interchangeable footprint. Manufacturer documentation.
2. Calculate conduction loss at the minimum input
On-resistance rises substantially as input voltage falls, so the attractive 14 milliohm typical value at 3.6 V does not describe operation near 1 V. Use the relevant voltage and temperature conditions to calculate load drop and I²R loss. Review the 2 A maximum-current headline with package and thermal limits rather than treating it as a universal guarantee. Trace resistance and connector loss may also become significant when the switched rail has little voltage margin. Manufacturer documentation.
3. Make the active-high enable state unambiguous
ON high enables the power path, while ON low disables it. Check the specified threshold against the actual controller rail and define what happens during GPIO reset, controller power loss and slow supply ramps. An example for an active-low relative cannot be copied unchanged. Add appropriate bias if needed and verify current paths when one device is unpowered. A stable running-state command alone does not prove that the load remains safely off during the entire boot sequence. Manufacturer documentation.
4. Choose the correct fixed rise-time option
TPS22922 has a different turn-on behavior from the slower TPS22922B. The datasheet gives illustrative rise times near 30 microseconds and 200 microseconds respectively under the stated 1.8 V test conditions. Those are not programmable settings on the same installed device. Estimate charging current from capacitance times voltage slew, include any active load during the ramp and verify source droop. A suffix substitution can change inrush even when its final on-state resistance looks acceptable. Manufacturer documentation.
Newest in the store
5. Account for the internal discharge path
When TPS22922 or TPS22922B is disabled, a nominal 65 ohm internal path discharges VOUT to ground. TPS22921 lacks that feature. Output fall time still depends on capacitance, load and other connected sources; it is not instant removal of stored energy. Review back-powered output cases, because another supply can feed the discharge path. Where the rail must retain voltage while isolated, this device behavior may be inappropriate even though its ordinary on-state switching performance is suitable. Manufacturer documentation.
6. Do not assume reverse-current isolation or fault limiting
Use only the protections explicitly documented for this part. A P-channel load switch with a discharge feature is not automatically an ideal diode, reverse-blocking power multiplexer or programmable overcurrent protector. Review all possible externally driven output and signal-pin paths against the device limits. Provide appropriate upstream protection for the load fault and wiring. If guaranteed reverse isolation is essential, select a device whose reverse-current operation is specified for the required powered and unpowered states. Manufacturer documentation.
7. Measure both the charging and discharge intervals
Use representative capacitance and a protected supply to capture ON, input voltage, output voltage and load current. Evaluate turn-on droop, on-state drop and turn-off fall time separately. Repeat the lowest input and relevant temperature conditions, recording the exact suffix and package implementation. Check whether the connected subsystem remains partially powered through communication pins after its main rail falls. Accept an off-state policy based on actual residual voltage and current paths, not merely the host having issued a disable command. Manufacturer documentation.
Related reading: TPS22910A Load Switch: 7 Checks for Active-Low Power Control.
Catalog note: The exact-part search did not return a matching Epro listing during preparation. Check the current catalog; this guide makes no price, availability or included-accessory claim.