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Power Supply 0.1 µF 1000 µF Optimum 2.7 V to 5.5 V PC Board Overcurrent Response TPS2062 OC1 GND EN1 IN EN2 OUT1 OUT2 OC2 Block of Circuitry Block of Circuitry SLVS490I – DECEMBER 2003 – REVISED OCTOBER 2009 www.ti.com Figure 30. Typical Hot-Plug Implementation By placing the TPS206x between the VCC input and the rest of the circuitry, the input power reaches these devices first after insertion. The typical rise time of the switch is approximately 1 ms, providing a slow voltage ramp at the output of the device. This implementation controls system surge currents and provides a hot-plugging mechanism for any device. DETAILED DESCRIPTION Power Switch The power switch is an N-channel MOSFET with a low on-state resistance. Configured as a high-side switch, the power switch prevents current flow from OUT to IN and IN to OUT when disabled. The power switch supplies a minimum current of 1 A. 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. Enable (ENx or ENx) The logic enable disables the power switch and the bias for the charge pump, driver, and other circuitry to reduce the supply current. The supply current is reduced to less than 1 μA when a logic high is present on ENx, or when a logic low is present on ENx. A logic zero input on ENx, or a logic high input on ENx restores bias to the drive and control circuits and turns the switch on. The enable input is compatible with both TTL and CMOS logic levels. Overcurrent (OCx) The OCx 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. A 10-ms deglitch circuit prevents the OCx signal from oscillation or false triggering. If an overtemperature shutdown occurs, the OCx is asserted instantaneously. 22 Copyright © 2003–2009, Texas Instruments Incorporated |
