BQ500110_11 Datasheet, PDF (13/25 Pages) Texas Instruments – Qi Compliant Wireless Power Transmitter Manager

www.ti.com
bq500110
SLUSAE0A – NOVEMBER 2010 – REVISED APRIL 2011
Thermal Protection
The bq500110 can provide thermal protection to the transmitter. An external NTC resistor can be placed in the
most thermally challenged area, which usually is the center of the transmitting coil, and connected between V_CC
and the dedicated pin 3. The threshold on the pin 3 is set 1.25V. The NTC resistor and the resistor from the pin 3
to GND create temperature sensitive divider. User has full flexibility choosing the NTC resistor and the value of
the resistor from the pin 3 to GND to set the desired temperature when the system shuts down.
R_{TEMP_IN} = 0.6097 x R_NTC(T_MAX)
(1)
The system will attempt to restore normal operation after approximately five minutes being in the suspended
mode due to tripping the over-temperature threshold, or if the receiver is removed.
Audible Notification on Initiation of Power Transfer
The bq500110 is capable of activating two types of buzzers to indicate that power transfer has begun. Pin 15
outputs a high logic signal for 0.5s which is suitable to activate DC type buzzers with built in tone generation,
other types of sound generators, or custom indication systems. Pin 24 outputs a 0.2s, 4000Hz square wave
signal suitable for inexpensive AC type ceramic buzzers.
Gate Driver Modes
The inner PID (proportional-integral-derivative) loop feeds the variable frequency driver, which produces a digital
signal of 50% duty cycle with variable frequency. In operation, the inner PID loop calculates the necessary
frequency, which is then generated by the variable frequency driver. The variable frequency is then fed into a
MOSFET power train that excites the serial resonance transmitter coil.
The bq500110 can operate with several types of MOSFET gate drivers to accommodate various power train
topologies. The DRV_SEL input, pin 9, selects between two modes of drive. When pin 9 is pulled to GND, the
DRV_EN output, pin 13, will be driven high while the COIL_PWM output sends a square waveform to the gate
driver. The most typical and suggested solution is to use a synchronous buck driver like the TPS28225 that
drives n-channel upper and lower power MOSFETs with a safe dead-time.
An alternative solution that may utilize a combination of p-channel and n-channel MOSFETs can be used when
input DRV_SEL input, pin 9, is pulled high to V_CC. In this case the outputs COIL_PWM and DRV_EN, both output
the square waveforms to discrete gate drivers. The dead-time is provided by pulse duration difference between
the two waveforms.
Coil Disable Signal
As the part of the WPC 1.0 compliance communication protocol, the bq500110 has the coil damping control
signal that is provided on the output COIL_DIS, pin 8. The damping signal activates the MOSFET that loads the
output of the half-bridge with the 100Ω resistor.
Power-On Reset
The bq500110 has an integrated power-on reset (POR) circuit that monitors the supply voltage. At power-up, the
POR circuit detects the V33D rise. When V33D is greater than VRESET, the device initiates an internal startup
sequence. At the end of the startup sequence, the device begins normal operation.
External Reset
The device can be forced into a reset state by an external circuit connected to the RESET pin. A logic low
voltage on this pin holds the device in reset. To avoid an erroneous trigger caused by noise, a 10kΩ pull up
resistor to 3.3V is recommended.
Non-Volatile Memory Error Correction Coding
The device uses Error Correcting Code (ECC) to improve data integrity and provide high reliability storage of
Data Flash contents. ECC uses dedicated hardware to generate extra check bits for the user data as it is written
into the Flash memory. This adds an additional six bits to each 32-bit memory word stored into the Flash array.
These extra check bits, along with the hardware ECC algorithm, allow for any single bit error to be detected and
corrected when the Data Flash is read. Note that the Data Flash configuration has been factory programmed and
is not generally available for customization.
Copyright © 2010–2011, Texas Instruments Incorporated
Product Folder Link(s) :bq500110
Submit Documentation Feedback
13