TPS2020Q1, TPS2021Q1

TPS2022Q1, TPS2023Q1, TPS2024Q1

POWERDISTRIBUTION SWITCHES

SGLS260C − SEPTEMBER 2004 − REVISED NOVEMBER 2004

3

POST OFFICE BOX 655303

detailed description

power switch

The power switch is an N-channel MOSFET with a maximum on-state resistance of 50 m

as a high-side switch, the power switch prevents current flow from OUT to IN and IN to OUT when disabled.

charge pump

An internal charge pump supplies power to the driver circuit and provides the necessary voltage to pull the gate of

the MOSFET above the source. The charge pump operates from input voltages as low as 2.7 V and requires little

supply current.

driver

The driver controls the gate voltage of the power switch. To limit large current surges and reduce the associated

electromagnetic interference (EMI) produced, the driver incorporates circuitry that controls the rise times and fall

times of the output voltage. The rise and fall times are typically in the 2-ms to 9-ms range.

enable ( EN )

The logic enable disables the power switch, the bias for the charge pump, driver, and other circuitry to reduce the

supply current to less than 10

µA when a logic high is present on EN. A logic zero input on EN restores bias to the

drive and control circuits and turns the power on. The enable input is compatible with both TTL and CMOS logic

levels.

overcurrent ( OC )

The OC open drain output is asserted (active low) when an overcurrent or overtemperature condition is

encountered. The output remains asserted until the overcurrent or overtemperature condition is removed.

current sense

A sense FET monitors the current supplied to the load. The sense FET measures current more efficiently than

conventional resistance methods. When an overload or short circuit is encountered, the current-sense circuitry

sends a control signal to the driver. The driver, in turn, reduces the gate voltage and drives the power FET into its

saturation region, which switches the output into a constant current mode and holds the current constant while

varying the voltage on the load.

thermal sense

An internal thermal-sense circuit shuts off the power switch when the junction temperature rises to approximately

140

°C. Hysteresis is built into the thermal sense circuit. After the device has cooled approximately 20°C, the switch

turns back on. The switch continues to cycle off and on until the fault is removed.

undervoltage lockout

A voltage sense circuit monitors the input voltage. When the input voltage is below approximately 2 V, a control

signal turns off the power switch.