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| BQ24232H_15 Datasheet, PDF (15/42 Pages) Texas Instruments – bq2423xx USB-Friendly Lithium-Ion Battery Charger and Power-Path Management IC | |||
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www.ti.com
bq24230H, bq24232H
SLUSBI8A â JANUARY 2014 â REVISED DECEMBER 2014
Feature Description (continued)
The bq2423xH is USB-IF compliant for the inrush current testing. The USB specification allows up to 10 μF to be
hard-started, which establishes 50 μC as the maximum inrush charge value when exceeding 100 mA. The input
current limit for the bq2423xH prevents the input current from exceeding this limit, even with system
capacitances greater than 10 μF. The input capacitance to the device must be selected small enough to prevent
a violation (<10 μF), as this current is not limited. Figure 12 demonstrates the start-up of the bq2423xH and
compares it to the USB-IF specification.
10 μC
50 μC
100 μs/div
Figure 12. USB-IF Inrush Current Test
The input current limit selection is controlled by the state of the EN1 and EN2 pins as shown in Table 1. When
using the resistor-programmable current limit, the input current limit is set by the value of the resistor connected
from the ILIM pin to VSS and is given by the equation:
IIN-MAX = KILIM/RILIM
The input current limit is adjustable up to 500 mA. The valid resistor range is 3.2 k⦠to 8 kâ¦.
When the IN source is connected, priority is given to the system load. The DPPM and Battery Supplement
modes are used to maintain the system load. Figure 13 illustrates examples of the DPPM and supplement
modes. These modes are explained in detail in the following sections.
Table 1. EN1/EN2 Settings
EN2
EN1 MAXIMUM INPUT CURRENT INTO IN PIN
0
0
100 mA. USB100 mode
0
1
500 mA. USB500 mode
1
0
Set by an external resistor from ILIM to VSS
1
1
Standby (USB suspend mode)
9.3.3.1.1 Input DPM Mode, VIN-DPM
The bq2423xH uses the VIN-DPM mode for operation from current-limited USB ports. When EN1 and EN2 are
configured for USB100 (EN2=0, EN1=0) or USB500 (EN2=0, EN2=1) modes, the input voltage is monitored. If
VIN falls to VIN-DPM, the input current limit is reduced to prevent the input voltage from falling further. This prevents
the bq2423xH from crashing poorly designed or incorrectly configured USB sources.
Copyright © 2014, Texas Instruments Incorporated
Product Folder Links: bq24230H bq24232H
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