BQ50002 Datasheet, PDF (10/35 Pages) Texas Instruments – Low-Cost 5-V Wireless Power Transmitter Analog Front

bq50002
SLUSBW1A – OCTOBER 2015 – REVISED OCTOBER 2015
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Feature Description (continued)
7.3.2 PWM Control
7.3.2.1 PWM_CTRL Input
bq50002 operates in two modes:
Direct PWM Control Mode and Self Switching. The mode of operation is set by the state of PWM_CTRL input
when EN=HIGH. This is intended for control by bq500511.
7.3.2.2 PWM1, PWM2
bq50002 passes external PWM inputs to drive gate drivers when the following conditions hold:
• EN pin is HIGH
• PWM_CTRL pin is HIGH
• Typical Dead Time shall be better than 20 ns. Minimum PWM input pulse duration that changes SW output
should be less than 50 ns.
7.3.2.3 Self-Switching
bq50002 follows the commands from the controller to adjust the internal oscillator frequency up or down to adjust
output power levels when the following conditions apply:
• PWM_CTRL pin is LOW
• PWM1/CLK_IN behaves as CLK_IN pin. The CLK_IN rising edge triggers frequency increase or decrease by
one step based on the state of PWM2/UP_DN pin.
• Self-switching starts at F=175 kHz when PWM_CTRL state changes from HIGH to LOW. Operating frequency
changes are based on the inputs of UP_DN, CLK_IN and MODE.
• The CLK_OUT pin outputs 3.3V logic level with frequency equal in value to the current switching frequency.
The rising edge of this signal coincides with the rising edge of the SW1 waveform. The duty factor of the
signal on CLK_OUT pin is 50%.
• bq50002 increases the frequency (reduces delivered power) if:
– PWM_CTRL pin is LOW
– MODE pin is LOW
– UP_DN pin is LOW
– CLK_IN pin changes its state from LOW to HIGH (rising edge)
• bq50002 decreases the frequency (increases delivered power) if:
– PWM_CTRL pin is LOW
– MODE pin is LOW
– UP_DN pin is HIGH
– CLK_IN pin changes its state from LOW to HIGH (rising edge)
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