TPS2030, TPS2031, TPS2032, TPS2033, TPS2034

POWERDISTRIBUTION SWITCHES

SLVS190B − DECEMBER 1998 − REVISED MARCH 2004

3

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detailed description

power switch

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

Configured 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

very 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 low is present on EN . A logic high 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 will remain 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.