BQ50002 Datasheet, PDF (11/35 Pages) Texas Instruments – Low-Cost 5-V Wireless Power Transmitter Analog Front

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bq50002
SLUSBW1A – OCTOBER 2015 – REVISED OCTOBER 2015
Feature Description (continued)
7.3.2.4 Duty Cycle Adjustment
bq50002 follows the commands from the controller to adjust the internal oscillator duty cycle up or down to adjust
power output levels when the following conditions hold:
• The internal clock is set to the highest frequency tap, 205 kHz
• PWM_CTRL pin is LOW
• MODE pin is HIGH
• bq50002 decreases the duty cycle (reduces delivered power) if:
– The internal clock is set to the highest frequency tap, 205 kHz or at frequency at which MCU commands
MODE = 1
– PWM_CTRL pin is LOW
– MODE pin is HIGH
– UP_DN is LOW
– CLK_IN pin changes state from LOW to HIGH (rising edge)
– bq50002 ignores CLK_IN signals when minimum duty factor position of 10% is reached
• bq50002 increases the duty cycle (increases delivered power) if:
– The internal clock is set to the highest frequency tap, 205 kHz at frequency at which MCU commands
MODE = 1
– PWM_CTRL pin is LOW
– MODE pin is HIGH
– UP_DN is HIGH
– CLK_IN pin changes state from LOW to HIGH (rising edge)
– bq50002 ignores CLK_IN signals when maximum duty factor position of 50% is reached. bq50002 will
resume clock frequency adjustment mode only when the duty cycle adjustment has reached the 50% state
and MODE=0.
7.3.3 Current Sense Amplifier
To support foreign object detection (FOD), bq50002 senses the average input current to the device. The
integrated current sense amplifier has voltage gain of 50.
7.3.4 Voltage Regulator
bq50002 has an integrated low-dropout (LDO) voltage regulator which supplies power to the companion
bq500511 controller. The BP3 pin supplies a regulated 3-V voltage supply and should have a 2.2-µF capacitor
tied to GND.
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