SWCS049B datasheet(56/144 Pages) TI

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TPS65911

SWCS049S – JUNE 2010 – REVISED AUGUST 2018

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Detailed Description

6.5.3.12 Comparators: COMP1 and COMP2

The TPS65911 device has three comparators for system status detection/control. One comparator detects

the voltage at pin VCC7. When VCC7 > VMBHI, the comparator initiates a NO SUPPLY-to-OFF transition

and the VMBHI_IT interrupt is generated. When VCC7 < VMBLO, the comparator initiates an

ACTIVE/SLEEP/OFF-to-BACKUP transition. When both VCC7 and backup battery are below VBPNR, the

device goes to the NO SUPPLY state.

Comparators COMP1 and COMP2 detect the voltage of VCCS. Programmable comparator COMP1 is

intended for detecting if battery voltage is high enough for an OFF-to-ACTIVE transition of the TPS65911

device. For an OFF-to-ACTIVE transition VCCS must be > VMBCH (primary battery charged) and a level

below the comparator threshold prevents the power-up sequence. The threshold can be set from 2.5 to

3.5 V with 50-mV steps through VMBCH_SEL. The comparator has debouncing so that VCCS must stay

above VMBDCH (VMBCH – 0.1 V) for a debouncing period of 61 µs. The comparator can be bypassed if

the threshold selection is set to 0. The default threshold is set in the boot configuration.

In a system with a multiple-cell battery, the battery level is sensed through an external resistor divider. The

TPS65911 device has an internal buffer at the VCCS input, which must be used with the external resistive

divider.

In a single-cell system, VCCS and VCC7 are connected directly to the battery. The VCCS input buffer can

be bypassed to minimize power consumption. The buffer bypass is controlled with the VMBBUF_BYPASS

bit in the boot configuration.

COMP2 is disabled by default and can be enabled by software. The comparator trigger generates an

interrupt which is programmable on the rising (VMBCH2_H_IT) or falling edge (VMBCH2_L_IT), hence the

comparator can be used for detecting high or low battery scenarios. COMP2 generates an interrupt for the

host. In sleep mode, this creates a wake-up interrupt for the host. In off mode, the comparator trigger

generates a turnon event. In backup or no supply modes, the comparator is not active.

The COMP2 threshold can be set from 2.5 to 3.5 V with 50-mV steps. Enabling the comparator is done

through the voltage threshold selection bit VMBDCH2_SEL, which is set to 0 by default.

SWCS049B 数据表(PDF) 56 Page - Texas Instruments