TPS77001DBVR

The TPS77001DBVR is an ultra-low-power 50 mA low-dropout (LDO) linear voltage regulator from Texas Instruments, housed in a 5-pin SOT-23 (DBV) package. It is the adjustable-output variant of the TPS770 family, supporting output voltages from 1.2V to 5.5V set by an external resistor divider. The device uses a PMOS pass transistor to achieve an extremely low dropout voltage of typically 35 mV at 50 mA load, and an ultra-low quiescent current of just 17 µA at full load that remains stable across the entire output current range (0 mA to 50 mA).

The TPS77001DBVR features a logic-controlled enable (EN) pin that shuts down the regulator to a standby current of only 1 µA typical, making it ideal for battery-powered applications where power conservation is critical. The output voltage accuracy is 3% over load, line, and temperature. The internal reference voltage is 1.224V, and the feedback (FB) pin allows the external resistor divider to set the desired output voltage.

The device operates from an input voltage range of 2.7V to 10V (absolute maximum 13.5V), making it suitable for conditioning supply rails from single-cell Li-Ion batteries, 3.3V or 5V logic supplies, or 9V battery sources. The TPS770 family also includes fixed-output versions at 1.2V, 1.5V, 1.8V, 2.5V, 2.7V, 2.8V, 3.0V, 3.3V, and 5.0V.

Overcurrent protection and thermal shutdown are built in for reliability. The device requires a minimum 4.7 µF output capacitor for stability (tantalum or aluminum electrolytic recommended; ceramic capacitors may require series resistance). The operating junction temperature range is -40°C to +125°C. The thermal resistance (junction-to-ambient) is 180°C/W for the SOT-23-5 package.

The DBVR suffix denotes the SOT-23-5 package in tape and reel format (3,000 units per reel). The device marking code is PCPI. The device is RoHS compliant and classified as EAR99. TI recommends the TLV767 or TPS7A24 as newer alternatives with wider input range, better PSRR, and lower Iq for new designs.

Key specifications summary: 50 mA maximum output current, 35 mV typical dropout at 50 mA, 17 µA typical quiescent current, 1 µA standby current, 60 dB PSRR, 190 µVrms output noise, 3% output accuracy, adjustable output from 1.2V to 5.5V.

The TPS77001DBVR operates as a PMOS-based low-dropout linear voltage regulator with adjustable output voltage and logic-controlled enable.

PMOS Pass Element: Unlike conventional LDO regulators that use a PNP pass transistor, the TPS770 employs a PMOS pass element. The key advantage is that a PMOS transistor behaves as a voltage-driven device with very low gate current, resulting in ultra-low quiescent current (17 µA typical) that is essentially independent of the output load current. In contrast, a PNP-based LDO draws base current proportional to the load, increasing quiescent current at higher loads. The PMOS pass element also behaves as a low-value resistance when fully enhanced, producing the very low dropout voltage of 35 mV at 50 mA that is directly proportional to load current.

Voltage Regulation Loop: The output voltage is sensed at the FB pin through an external resistor divider (R1 from VOUT to FB, R2 from FB to GND). An internal error amplifier compares the divided output voltage against the 1.224V internal bandgap reference. The error amplifier output drives the PMOS gate to maintain regulation. The output voltage is set by: VOUT = VREF x (1 + R1/R2), where VREF = 1.224V. The recommended R2 value is approximately 250 kohm to minimize divider current, and R1 is calculated accordingly.

Enable and Shutdown: The EN pin provides logic-controlled shutdown. When EN is driven low (below 0.5V), the PMOS pass element is turned off and the regulator enters standby mode, drawing only 1 µA typical. When EN is driven high (above 1.5V), the regulator is enabled and operates normally. The EN pin can be tied directly to IN for always-on operation. During shutdown, the output is discharged through internal circuitry and the FB pin goes high impedance.

Current Limiting and Thermal Protection: The device includes an internal current limit circuit that restricts the output current to a safe level (typically 200-300 mA) during fault conditions such as output short circuits. If the junction temperature exceeds the thermal shutdown threshold (approximately 160°C), the regulator turns off the pass element. It automatically restarts when the junction temperature drops below the hysteresis threshold. These protection mechanisms prevent damage from overcurrent or overheating but do not guarantee safe operation under sustained fault conditions.

Stability and Output Capacitor: The regulator requires a minimum 4.7 µF output capacitor for stability. The ESR (equivalent series resistance) of the output capacitor affects loop stability. Tantalum or aluminum electrolytic capacitors with ESR in the range of 0.1 to 10 ohms are recommended. Ceramic capacitors with very low ESR (below 0.1 ohm) may cause instability unless a small series resistor (1-2 ohm) is added. A 0.1 µF ceramic input bypass capacitor is also recommended to improve transient response and reduce input impedance.