Hysteresis

ON

OFF

8.5

9

TPS65320-Q1

SLVSAY9A – DECEMBER 2012 – REVISED APRIL 2013

www.ti.com

Charge-Pump Operation

The LDO has an internal charge pump which turns on or off depending on the input voltage. The charge-pump

switching circuitry does not cause conducted emissions to exceed required thresholds on the input voltage line.

The charge-pump switching thresholds are hysteretic. Figure 21 shows the typical switching thresholds for the

charge pump.

Figure 21. Charge-Pump Switching Thresholds

Table 1. Typical Quiescent Current Consumption

Charge Pump ON

Charge Pump OFF

300 µA

40 µA

Low-Voltage Tracking

At low input voltages, the regulator drops out of regulation, and the output voltage tracks input minus a voltage

and can possibly eliminate the need to use a boost convertor during cold-crank conditions.

Power-Good Output, nRST

The nRST pin is a push-pull output. The power-on-reset output asserts low until the output voltage on LDO_OUT

exceeds the setting thresholds (91%) and the deglitch timer has expired. Additionally, whenever the EN2 pin is

low or open, nRST immediately asserts low regardless of the output voltage. If a thermal shutdown occurs due to

excessive thermal conditions, this pin also asserts low.

Thermal Shutdown

The device implements an internal thermal shutdown to protect itself if the junction temperature exceeds 170°C

(typical). The thermal shutdown forces the device to stop switching when the junction temperature exceeds the

thermal trip threshold. Once the junction temperature decreases below 160°C (typical), the device re-initiates the

power-up sequence.

Modes of Operation

The device has two hardware enable pins, and one can turn off either the buck or the LDO by pulling the enable

pin low, as listed in Table 2. One unique feature of the TPS65320-Q1 device is the input auto source of the LDO.

With both the buck and the LDO enabled, the LDO gets input from the output of the buck through the VIN_LDO

pin. In this mode, the buck output voltage must be higher than the LDO output voltage. With the buck disabled

and the LDO still enabled, the input of the LDO changes automatically from VIN_LDO to VIN. This is helpful for

standby operations which need a very low standby current, such as automotive infotainment, telematics, and so

18

Submit Documentation Feedback

Copyright © 2012–2013, Texas Instruments Incorporated

Product Folder Links: TPS65320-Q1