ZHCS958G June 2012 – September 2017 BQ24392
PRODUCTION DATA.
7 Detailed Description
7.1 Overview
The BQ24392 is a USB 2.0 high-speed isolation switch with charger detection capabilities for use with micro and mini-USB ports. Upon plugin of a Battery Charging Specification 1.2 (BCv1.2) compliant, Apple™, TomTom™, or other USB charger into a micro or mini-USB connector, the device will automatically detect the charger and operate the USB 2.0 high-speed isolation switch.
The BQ24392 device is powered through VBUS when a charger is attached to the micro or mini-USB port and has a 28-V tolerance to avoid the need for external protection.
7.2 Functional Block Diagram
7.3 Feature Description
7.3.1 Charger Detection
Figure 3. Charge Detection Block Diagram
When a micro or mini-USB accessory is inserted into the connector and once VBUS is greater than VVBUS_VALID threshold, the BQ24392 will enter into the Data Contact Detection (DCD) state which includes a 600-ms timeout feature that is prescribed in the USB Battery Charging Specification version 1.2 (BCv1.2). If the micro or mini-USB accessory is determined to be USB BCv1.2 compliant, a 130-ms debounce period will initiate and the BQ24392 will proceed to its primary detection and then secondary detection states to determine if a Dedicated Charging Port (DCP), Standard Downstream Port (SDP), or Charging Downstream Port (CDP) is attached to the USB-port. The minimum detection time for a DCP, SDP, and CDP is 130 ms, but can be as long as 600 ms due to the slow plug in effect.
If the GOOD_BAT pin is high, the USB 2.0 switches are automatically closed to enable data transfer after the device detects a Standard Downstream Port (SDP) or Charging Downstream Port (CDP) was connected.
If Data Contact Detection (DCD) fails, the BQ24392 proceeds to detect whether an Apple or TomTom charger was inserted by checking the voltage level on DP_CON and DM_CON. Thus, for Apple and TomTom chargers, detection time typically takes ~600 ms.
The 3 output pins CHG_AL_N, CHG_DET, and SW_OPEN change their status at the end of detection. Table 1 is the detection table with the GPIO status for each type of supported charger. More information on how to use the GPIOs is available in Using the BQ24392 GPIOs .
Table 1. Detection Table
| Device Type | VBUS | DP_CON (D+) |
DM_CON (D–) |
GOOD_BAT (Input) |
CHG_AL_N (Output) |
CHG_DET (Output) |
SW_OPEN (Output) |
Switch Status | Charge Current |
|---|---|---|---|---|---|---|---|---|---|
| Standard Downstream Port |
> 3.5 V | Pull-down R to GND | Pull-down R to GND | HIGH | LOW | LOW | LOW | Connected | Charge with 100 mA/ Change the input current based on enumeration |
| LOW | LOW | LOW | High-Z | Not Connected | Charge with 100 mA | ||||
| Charging Downstream Port |
> 3.5 V | Pull-down R to GND | VDM_SRC | HIGH | LOW | HIGH | LOW | Connected | Charge with full current |
| LOW | LOW | HIGH | High-Z | Not Connected | Charge with 100 mA | ||||
| Dedicated Charging Port |
> 3.5 V | Short to D– | Short to D+ | X | LOW | HIGH | High-Z | Not Connected | Charge with full current |
| Apple Charger | > 3.5 V | 2.0 < VDP_CON < 2.8 | 2.0 < VDM_CON < 2.8 | X | LOW | HIGH | High-Z | Not Connected | Charge with full current |
| TomTom Charger | > 3.5 V | 2.0 < VDP_CON < 3.1 | 2.0 < VDM_CON < 3.1 | X | LOW | HIGH | High-Z | Not Connected | Charge with full current |
| PS/2 Charger | > 3.5 V | Pull-up R to VVBUS | Pull-up R to VVBUS | X | LOW | LOW | High-Z | Not Connected | Charge with 100 mA |
| Non-compliant USB Charger |
> 3.5 V | Open | Open | X | LOW | LOW | High-Z | Not Connected | Charge with 100 mA |
| Any Device | < 3.5 V | Open | Open | X | High-Z | LOW | High-Z | Not Connected | No Charge |
| Any Device DBP Timer Expired |
> 3.5 V | X | X | LOW | High-Z | LOW | High-Z | Not Connected | No Charge |
If a charge has been detected and the GOOD_BAT pin is low, a Dead Battery Provision (DBP) timer is initiated. If the GOOD_BAT continues to be low for 30 minutes (maximum of 45 minutes), charging is disabled and CHG_AL_N goes into the High-Z state to indicate this. Toggling GOOD_BAT high after the DBP timer expires re-starts detection and the DBP timer.
7.4 Device Functional Modes
The BQ24392 has two functional modes USB switch ON and USB switch OFF.