Qi Receiver click
PID: MIKROE-2799
Weight: 28 g
Harvest energy wirelessly
Qi Receiver click
is based on the P9025AC 5W Qi wireless power receiver integrated circuit,
with the advanced Foreign Object Detection (FOD) feature, from IDT. The click utilizes the
principles of the inductive coupling for the purpose of wireless power transfer. Recently, the
WPS Qi wireless power transfer standard is becoming widely used, for example - wireless
charging of the batteries on many Qi wireless power charging compliant devices.
Qi Receiver click is well-suited for a wide range of applications, including cell phones, tablets,
PC peripherals, medical devices, small hand-held devices, in robotics, embedded electronics, etc.
Note:
Qi Receiver click has to be placed near the suitable Qi Transmitter, also known as the
charging pad, to successfully harvest the transmitted power.
Quick start guide
Follow these simple steps to power-up and begin using Qi Receiver click:
1. Place the Qi Receiver click so that the inductive coil is facing down, towards the transmitter.
2. Verify that the STAT LED is illuminated ‐ power is being transferred.
3. Connect the load to the output pads.
How the Qi Receiver click works
The click utilizes the effects of the electromagnetic induction to wirelessly transfer energy, a
phenomenon in which the electromotive force (i.e. voltage) is generated across the electrical
conductor, under the influence of a variable magnetic field. It uses the planar copper coil as an
inductive element.
Qi Receiver click relies on the wireless power transfer standard, developed by the Wireless
Power Consortium, to both provide and monitor current and voltage. This standard involves
digital communication, used to transmit the information back to the charging pad. Depending on
the received information packets, charging pad regulates the strength of the variable magnetic
field, which in return generates more or less power on the receiver coil.
When Qi Receiver click is placed on a WPS Qi compliant charging pad, it responds to the
transmitter's "ping" signal, by rectifying the AC power from the transmitter and storing it on a
capacitor connected to the VRECT. During the "ping" phase, the rectifier provides about 5V at
the VRECT pin. An internal linear voltage regulator provides the supply voltage for the digital
section of the P9025AC, enabling the Qi protocol communication, so that the receiver can
synchronize with the charging pad. After the initial synchronization, the system enters the Power
Transfer state and the actual power transfer process is started, which is indicated by the Status
LED. The voltage on the output connector of the Qi Receiver click is kept constant and it’s 5.3V,
so the eventual voltage drops under a heavy load are accounted for. Since the P9025AC can
withstand up to 5W, it should be able to deliver up to 1A of current, on the output header VOUT.
One special feature of this device is the possibility to detect foreign metal objects in its field. The
presence of the foreign metallic objects in the charging field can be unwanted - even dangerous.
When found in the alternating magnetic field, the metal object can be heated up by the eddy
currents that are generated inside of it. Also, this heat can be translated into a power loss, which
can be especially problematic if the object is actually a part of the power harvesting device.
To overcome this problem, the P9025AC employs advanced FOD techniques to both accurately
measure its received power, and to accurately compensate all of its known losses. This
compensation is implemented by means of a curve fitting table. This table supports up to 10
different curves stored in OTP (One Time Programmable) memory and one volatile memory
location, programmed by the I2C bus. Additionally, the selected fitting curve can be offset by
300mW, by the means of a resistor connected to the FOD2 pin, so even better power adaptation
can be achieved.
The click also features the overvoltage, overcurrent and thermal shutdown. If any of these
conditions occur on the output terminal, the LDO gets shut down and the End of Power packet is
sent, so the charging pad also stops transmitting the power. Additionally, an interrupt can be
generated on the INT pin of the Proximity 3 click.
Note:
This device can’t be used to charge the batteries on its own. It can be coupled with the
specialized battery charging circuitry, as for example Charger click so that the harvested power
can be used for battery charging, too.
Specifications
On‐board modules P9025AC 5W Qi wireless power receiver
Interface
Input Voltage
Click board size
GPIO,I2C
3.3V or 5V
L (57.15 x 25.4 mm)
Pinout diagram
This table shows how the pinout on
Qi Receiver click
corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
16
15
END
INT
Notes
End of charge input pin
Interrupt output
Over‐temperature input
TEOP
1 AN PWM
Enable
EN
2 RST
INT
Status output
ST
3 CS
NC
4 SCK
TX
RX
SCL
14
13
12
11
10
9
NC
NC
SCL
SDA
5V
GND
I2C clock
I2C data
Power supply
Ground
NC
5 MISO
NC
6 MOSI SDA
Power supply
Ground
3.3V
7 3.3V
5V
GND
8 GND GND
END pin
- End of charge input pin. Used to terminate power transfer - active high.
INT pin
- Interrupt output. Open drain output pin - requires a pullup resistor.
TEOP pin
- Over-temperature input pin. Used to terminate power transfer - active high.
ST pin
- Status output. A logic low state indicates that power is being transferred.
Qi Receiver click maximum ratings
Description
Regulated output voltage
Output current limit
Operation junction temperature 0
Min Typ Max Unit
5.04 5.3 5.56
1.6
V
A
125 °C
Onboard settings and indicators
Label
JP1
Name
Default
Description
Power/logic voltage level selection. Left position 3.3V, right position 5V
Power LED indicates that the click is powered on
Charging status indication LED
PWR.SEL. Left
PWR Power LED
‐
STAT Status LED
‐
Additional pins
Name I/O
Description
VOUT O Regulated voltage output
GND
‐
Ground connection
Note:
Headers for additional pins come with the packaging, so the users can solder them on the
front or on the back of the board, according to their needs.
Software Support
We provide a library for the Qi Receiver click on our LibStock page, as well as a demo
application (example), developed using MikroElektronika compilers. The demo can run on all
the main MikroElektronika development boards.
Library Description
This library contains functions for reading from and writing to the registers of Qi Receiver click.
Key functions:
float QIRCV_readV ()
- Reads VRECT value from the click's registers.
float QIRCV_readI ()
- Reads IOUT value from the click's registers.
uint8_t QIRCV_readReg (uint8_t inputAddress)
- Generic read function for any register.
void QIRCV_writeReg (uint8_t inputAddress, uint8_t inputData)
- Generic write
function for any register.
Examples Description
This example demonstrates reading of Qi Receiver registers. It will output the VRECT value and
IOUT value. The VRECT can be used to indicate how well the receiver is placed, where higher
values mean that the position is better. The IOUT is the output current of the system.
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