Datasheet

bq500210

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SLUSAL8C –JUNE 2011–REVISED SEPTEMBER 2012

In some battery charging applications there is a benefit to continue the charging process in trickle charge mode

to top off the battery. There are several information packets in the WPC specification related to the levels of

battery charge – Charge Status. The bq500210 uses these commands in association with some of the LED

modes described in Table 2 to enable the top-off charging pattern. When CS100 LED mode is enabled, the

bq500210 will change the LED indication to reflect charge complete when a Charge Status = 100% message is

received, but unlike the response to an EPT, it will not halt power transfer while the LED is solid green. The

mobile device can use a CS100 packet to enable trickle charge mode.

Note that all options related to CS100 have an effect on the LEDs only; they do not have any impact on actual

power transfer which continues uninterrupted.

Two more optional modes are available which can be used to change the LED mode back to indicate charging

after the CS100 has forced the charge complete output:

• If CS90 is enabled, a Charge Status message indicating less than 90% charge will force the LED output to

indicate charging (typically a slow blinking green LED).

• When CS6MIN is enabled, and if the bq500210 does not detect another CS100 packet for six minutes, it will

assume the receiver charge has dropped significantly and will turn on charging status indication.

APPLICATION INFORMATION

The application diagram for the transmitter with reduced standby power consumption is shown in Figure 6.

Power reduction is achieved by periodically shutting down the bq500210 while LED and housekeeping control

functions are continued by U4 – the low-cost, low quiescent current microcontroller MSP430G2001. When U4 is

present in the circuit (which is set by a pull-up resistor on bq500210 pin 25), the bq500210 at first power-up

boots the MSP430G2001 with the necessary firmware and the two chips operate in tandem.

During standby operation, the bq500210 periodically issues SLEEP command, Q12 pulls down the enable pin on

U2, the TLV70033 LDO, which shut off power to the bq500210.

Meanwhile, the MSP430G2001 maintains the LED indication and stores previous charge state during this

bq500210 shut-off period.

This bq500210 shut-off period is set by the RC time constant network of R25, C38 (from Figure 6). WPC

compliance mandates the power transmitter controller awakes every 0.4s to produce an analog ping and check if

a valid device is present. Altering this time constant, therefore, is not advised.

Note: The user does not need to program the MSP430G2001, an off-the-shelf part can be used! The user cannot

modify or customize this firmware.

Product Folder Links: bq500210