DocID031237 Rev 2 11/32
STWBC-MC Pins functional description
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The STWBC-MC integrates a programmable deadtime between the active states of UPBL
and DNBL avoiding simultaneous conduction of power switches. The external gate driver
doesn't need to manage deadtim e.
The STWBC-MC requires the following capability to be supported by the gate driver:
UPBL = 0, DNBL = 0: in such case, the power half-bridge must be in the high
impedance state.
UPBL = 1, DNBL = 0: high side power switch must be ON.
UPBL = 0, DNBL = 1: low side power switch must be ON.
UPBL = 1, DNBL = 1: optional mode where both high and low side power switches
must be ON (simultaneous conduction).
While the power half-bridge is driven with the UPBL and DNBL signals, a low energy drive is
needed to run the coil quality factor estimation. For this function, the bridge is driven by
using the PWM_QFOD pin instead of UPBL (UPBL is 0 during th is operation) . PWM_QFOD
has to be connected to the low energy high side switch while DNBL is still used for the low
side low impedance switch drive.
In many situation the STWBC-MC requires a ¼ wave synchronization with the LC tank
connected to the half-bridge. A simple passive detector must be connected to the LC tank
and the WAVE_SNS pin. The WAVE_SNS pin should be limited to a 0.6 V swing.
4.4 Wireless power functions: TANK_VOLTAGE, ISENSE,
COIL_TEMP, SYMBOL_DETECT, CURRENT_DEMOD,
QFOD_ADC
The STWBC-MC requires monitor ing the peak voltage on the LC t ank as well as the rectified
current circulating in the tank. To do so, a peak voltage detector of the LC t ank must be
connected to the TAN K_VOLTAGE pin and a filtered current sensor must be connected to
the ISENSE pin .
For quality factor measurement, a high sensitivit y peak voltage de tector of the LC tank mu st
be connected to the QFOD_ADC pin.
The STWBC-MC requires external signal conditioning blocks to pre-demodulate the WPC
Qi messages. One of this block detects the effect of modulation on the LC tank voltage and
it must be connected to the SYMBOL_DETECT pin. Another block is required to detect the
effect of modulation on the LC tank current and it must be connected to the
CURRENT_DEMOD pin.
For safety reason the STWBC-MC is capable to monitor the temperature of the transmitting
coil. In order to do so, a NTC thermistor must be connected to the COIL_TEMP pin.
4.5 Input power supply management: VMAIN, QC_IO
The STWBC-MC monitors the input power supply volt age using the VMAIN pin. This voltage
is used for optimum programming of the DCDC converter but also for the wireless power
mode of the operation.
The STWBC-MC is cap able of requesting 12 V output volt age available from some USB wall
adaptors. While the USB wall adaptor provides 5 V by default, using a specific signaling on
the D+ and D- signals of the USB in terface, 12 V can be ob tained if supported . When 12 V is