BQ50002 Datasheet, PDF (8/35 Pages) Texas Instruments – Low-Cost 5-V Wireless Power Transmitter Analog Front

bq50002
SLUSBW1A – OCTOBER 2015 – REVISED OCTOBER 2015
7 Detailed Description
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7.1 Overview
The principle of wireless power transfer is simply an open-cored transformer consisting of transmitter and
receiver coils. The transmitter coil and electronics are typically built into a charger pad and the receiver coil and
electronics are typically built into a portable device, such as a smart phone. When the receiver coil is positioned
on the transmitter coil, magnetic coupling occurs when the transmitter coil is driven. The flux is coupled into the
secondary coil, which induces a voltage and current flows. The secondary voltage is rectified, and power can be
transferred effectively to a load, wirelessly. Power transfer can be managed through various closed loop control
schemes.
After power is applied and the transmitter device comes out of reset, it will automatically begin the process of
detecting and powering a receiver. The bq500511 sends a ping to detect the presence of a receiver on the pad.
After a receiver is detected, the bq500511 attempts to establish communication and begin power transfer. The
bq500511 is designed to operate with the bq50002 Wireless Power Transmitter Analog Front End to control a
full-bridge power stage to drive the primary coil. Through a simple interface the bq500511 instructs the bq50002
how much to increase or decrease power. The full bridge power stage allows for higher power delivery for a
given supply voltage.
7.2 Functional Block Diagram
BP3 4
GND 5
GND 6
GND 13
PWM1/CLK 1
PWM2/UPDN 32
PWM_CTRL 2
EN 3
MODE 10
CSP
+
VBG
VIN_GD
V4A
CSO
31
CSP
30
50x Amplifier
CSN
29
+
VBANDGAP
and
Supplies
Boot Regulator
Logic
D/A
Converter
D/A
Converter
Freq
Q1
Oscillator
Duty
Cycle
Q2
Boot Regulator
25 BOOT1
27 PVIN1
28 PVIN1
24 SW1
26 SW1
23 SW1
22 PGND
21 PGND
16 BOOT2
14 PVIN2
15 PVIN2
CLKOUT 9
Demodulator
2
Demodulator
1
7
12
DMOUT2 DMIN2
8
11
DMOUT2 DMIN2
18 SW2
19 SW2
17 SW2
20 PGND
8
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