ZHCS292H september 2009 – february 2021 BQ24040 , BQ24041 , BQ24045
PRODUCTION DATA
- 1
- 1 特性
- 2 應用
- 3 說明
- 4 Revision History
- 5 Device Comparison
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3 Feature Description
- 8.4
Device Functional Modes
- 8.4.1 CHG and PG LED Pull-up Source
- 8.4.2 Auto Start-up (BQ24041)
- 8.4.3 IN-DPM (VIN-DPM or IN-DPM)
- 8.4.4 OUT
- 8.4.5 ISET
- 8.4.6 PRE_TERM – Pre-Charge and Termination Programmable Threshold, BQ24040/5
- 8.4.7 ISET2
- 8.4.8 TS (BQ24040/5)
- 8.4.9 Termination and Timer Disable Mode (TTDM) - TS Terminal High
- 8.4.10 Timers, BQ24040 and BQ24045 only
- 8.4.11 Termination
- 8.4.12 Battery Detect Routine
- 8.4.13 Refresh Threshold
- 8.4.14 Starting a Charge on a Full Battery
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
8.4.5 ISET
An external resistor is used to Program the Output Current (50 to 1000mA) and can be used as a current monitor.
where
- IOUT is the desired fast charge current;
- KISET is a gain factor found in the electrical specification
For greater accuracy at lower currents, part of the sense FET is disabled to give better resolution. Figure 7-1 shows the transition from low current to higher current. Going from higher currents to low currents, there is hysteresis and the transition occurs around 0.15A.
The ISET resistor is short protected and will detect a resistance lower than ?340?. The detection requires at least 80mA of output current. If a “short” is detected, then the IC will latch off and can only be reset by cycling the power. The OUT current is internally clamped to a maximum current between 1.05A and 1.4A and is independent of the ISET short detection circuitry, as shown in Figure 8-5. Also, see Figure 9-14 and Figure 9-15.
Figure 8-4 Operation Over TS Bias Voltage (BQ24040)
Figure 8-5 Programmed/Clamped Out Current (BQ24040)