8.3.1 Input (IN)

The IN pin is a high-voltage-tolerant pin. A capacitor with a value higher than 0.1 µF is recommended to be connected close to this pin to better the transient performance.

8.3.2 Output (OUT)

The OUT pin is the regulated output based on the required voltage. The output has current limitation. During the initial power up, the regulator has a soft start incorporated to control the initial current through the pass element and the output capacitor.

In the event that the regulator drops out of regulation, the output tracks the input minus a drop based on the load current. When the input voltage drops below the UVLO threshold, the regulator shuts down until the input voltage recovers above the minimum startup level.

8.3.3 Output Capacitor Selection

For stable operation over the full temperature range and with load currents up to 150 mA, use a capacitor with an effective value between 2.2 µF and 100 µF and ESR smaller than 2 Ω. To better the load transient performance, an output capacitor, such as a ceramic capacitor with low ESR, is recommended.

8.3.4 Low-Voltage Tracking

At low input voltages, the regulator drops out of regulation and the output voltage tracks input minus a voltage based on the load current (I_L) and switch resistor. This tracking allows for a smaller input capacitor and can possibly eliminate the need for a boost converter during cold-crank conditions.

8.3.5 Thermal Shutdown

The TPS7B69xx-Q1 family of devices incorporates a thermal-shutdown (TSD) circuit as a protection from overheating. For continuous normal operation, the junction temperature should not exceed the TSD trip point. If the junction temperature exceeds the TSD trip point, the output turns off. When the junction temperature falls below the TSD trip point minus the hysteresis of TSD, the output turns on again. This cycling limits the dissipation of the regulator, protecting it from damage as a result of overheating.

The purpose of the design of the internal protection circuitry of the TPS7B69xx-Q1 family of devices is for protection against overload conditions, not as a replacement for proper heat-sinking. Continuously running the TPS7B69xx-Q1 family of devices into thermal shutdown degrades device reliability.

8.4.1 Operation With V_I Less Than 4 V

The TPS7B69xx-Q1 family of devices operates with input voltages above 4 V. The maximum UVLO voltage is 3 V and the device operates at an input voltage above 4 V. The device can also operate at lower input voltages; no minimum UVLO voltage is specified. At input voltages below the actual UVLO, the device shuts down.

8.4.2 Operation With V_I Greater Than 4 V

When V_I is greater than 4 V, if the input voltage is higher than V_O plus the dropout voltage, the output voltage is equal to the set value. Otherwise, the output voltage is equal to V_I minus the dropout voltage.