TPS22965DSGT

The TPS22965DSGT is a high-performance single-channel load switch from Texas Instruments, designed for power distribution and power domain management in portable and consumer electronics. Featuring an ultra-low on-resistance of 16 mΩ across a wide input voltage range, this device efficiently handles up to 6 A of continuous current while minimizing power loss and voltage drop across the switch.

At the heart of the TPS22965 is an N-channel MOSFET with a dedicated charge pump driver that provides full gate enhancement for low RON operation. The VBIAS pin supplies the internal control circuitry and charge pump, allowing the main power path (VIN to VOUT) to operate at voltages as low as 0.8 V. This dual-supply architecture is particularly useful in systems where a low-voltage rail must be switched but a higher voltage bias supply is available.

A key feature of the TPS22965 is its configurable rise time, controlled by an external capacitor on the CT pin. This allows designers to precisely tailor the output slew rate to match the load capacitance, minimizing inrush current and preventing supply voltage droop during turn-on. The quick output discharge feature provides a controlled discharge path when the switch is disabled, ensuring that downstream circuitry fully powers down and preventing floating node issues.

Available in a compact 8-pin WSON package with exposed thermal pad, the TPS22965DSGT offers excellent thermal performance in a minimal board footprint. The device operates over the full industrial temperature range of -40°C to +105°C and is fully RoHS compliant.

The TPS22965 load switch operates using several key functional blocks:

1. N-Channel Power MOSFET: The main power path consists of an N-channel MOSFET that connects VIN to VOUT when enabled. N-channel devices are used for their lower RON per area compared to P-channel devices, but require a gate drive voltage higher than the input voltage.

2. Charge Pump / Gate Driver: An integrated charge pump generates a voltage above VBIAS to fully enhance the gate of the N-channel MOSFET, achieving the minimum RON. This ensures low voltage drop even at full load current.

3. Rise Time Control (CT Pin): The CT pin controls the slew rate of the output voltage. An external capacitor connected from CT to GND sets the rate at which the gate is charged, directly controlling the output rise time. The relationship is approximately: SR = 0.38 × CT + 34 (µs/V). This is critical for limiting inrush current into capacitive loads.

4. Quick Output Discharge (QOD): When the switch is disabled (ON pin low), an internal 225 Ω resistor is connected between VOUT and GND. This actively discharges the output capacitor, preventing the output from floating and ensuring a known state for downstream circuits.

5. Control Logic: The ON pin provides enable/disable control. The input threshold is designed to be compatible with low-voltage logic (1.2 V to 3.3 V), allowing direct interface with microcontroller I/Os without level shifting.

6. Protection Features: The device includes undervoltage lockout (UVLO) on VBIAS, over-temperature protection, and overcurrent protection to ensure robust operation under fault conditions.

Note: Pins 1/2 and pins 7/8 are internally bonded together for improved current handling and thermal performance. Both pins should be connected on the PCB for optimal performance.

• Notebook and Tablet Power Management: Power gating for peripheral subsystems (display, audio, sensors) to reduce standby power consumption and extend battery life. The low off-state leakage is critical in always-on systems.
• Solid-State Drives (SSDs): Switching power rails for NAND flash arrays and controller cores. The 6A current capability supports high-density SSD designs with multiple flash channels.
• Consumer Electronics: Set-top boxes, residential gateways, and telecom equipment where dynamic power domain switching is used for power management and fault isolation.
• Battery-Powered Devices: Wearables, IoT sensors, and handheld instruments where sub-circuits are powered down to minimize drain on the battery during idle periods.
• Hot-Plug and Hot-Swap Applications: Controlling power to removable modules or peripherals, with controlled slew rate to prevent back-powering and minimize disturbance to the main supply.
• FPGA and ASIC Power Sequencing: Providing power-up sequencing between different voltage domains in multi-rail systems, where load switches offer a simpler alternative to complex power ICs for sequencing.