TI TPS2045AD

The TPS2045A through TPS2048A and TPS2055A through TPS2058A power-distribution switches are intended for applications where heavy capacitive loads and short circuits are likely to be encountered. These devices incorporate 80-mΩ N-channel MOSFET high-side power switches for power-distribution systems that require multiple power switches in a single package. Each switch is controlled by an independent logic enable input. Gate drive is provided by an internal charge pump designed to control the power-switch rise times and fall times to minimize current surges during switching. The charge pump requires no external components and allows operation from supplies as low as 2.7 V. When the output load exceeds the current-limit threshold or a short is present, these devices limit the output current to a safe level by switching into a constant-current mode, pulling the overcurrent (OCx) logic output low. When continuous heavy overloads and short circuits increase the power dissipation in the switch, causing the junction temperature to rise, a thermal protection circuit shuts off the switch to prevent damage. Recovery from a thermal shutdown is automatic once the device has cooled sufficiently. Internal circuitry ensures the switch remains off until valid input voltage is present. These power-distribution switches are designed to current limit at 0.5 A. The power switch is an N-channel MOSFET with a maximum on-state resistance of 135 mΩ (VI(IN) = 5 V). 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 of 250 mA per switch. 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. 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 4-ms range. 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 10 μA on the single and dual devices (20 μA on the triple and quad devices) when a logic high is present on ENX (TPS204xA) or a logic low is present on ENx (TPS205xA). A logic zero input on ENX or a logic high on ENx 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. The OCx open-drain output is asserted (active low) when an overcurrent or over temperature condition is encountered. The output will remain asserted until the overcurrent or over temperature condition is removed. 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. The TPS204xA and TPS205xA implement a dual-threshold thermal trip to allow fully independent operation of the power distribution switches. In an overcurrent or short-circuit condition the junction temperature rises. When the die temperature rises to approximately 140°C, the internal thermal sense circuitry checks to determine which power switch is in an overcurrent condition and turns off that switch.

• 80-mΩ High-Side MOSFET Switch
• 250 mA Continuous Current Per Channel
• Independent Thermal and Short-Circuit Protection With Overcurrent Logic Output
• Operating Range: 2.7-V to 5.5-V
• CMOS- and TTL-Compatible Enable Inputs
• 2.5-ms Typical Rise Time
• Undervoltage Lockout
• 10 μA Maximum Standby Supply Current for Single and Dual (20 μA for Triple and Quad)
• Bidirectional Switch
• Ambient Temperature Range, 0°C to 85°C
• ESD Protection