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AN11524

All information provided in this document is subject to legal disclaimers.

© NXP Semiconductors N.V. 2015. All rights reserved.

Application note

Rev. 1 — 17 February 2015 

14 of 54

NXP Semiconductors

AN11524

NXQ1TXA6 Evaluation Board

5.5 Current measurement

The current flowing into the power stage is determined by measuring the voltage across a 
22 m

 current sense resistor. The current measurement is needed for Foreign Object 

Detection (FOD). If FOD is not required, it can be disabled by configuring the resistor 
networks (refer to NXQ1TXA6 data sheet). The current measurement circuits can be 
removed. Connect the unused ISNS pin to ground, i.e. not left open. Note that FOD is 
required to pass Qi certification.

5.6 Bandgap reference voltage

NXQ1TXA6 wireless charging controller needs a band gap reference voltage (

0.5 % 

tolerance) for critical processing. The TL431 shunt regulator is used in the NXQ1TXA6 
Evaluation Board to provide this reference voltage.

5.7 DC-to-DC converter

A DC-to-DC buck converter steps the +12 V input down to +3.3 V, to supply the 
NXQ1TXA6 charging controller and other +3.3 V circuits. 

A Richtek RT8295A DC-to-DC converter is used in the NXQ1TXA6 evaluation board. An 
option for a linear regulator TDA3663 is available on board. Take note however, that at 
operating currents of the NXQ1TXA6 evaluation board, the efficiency of the applied 
DC-to-DC converter is better than a linear regulator.

5.8 Near Field Communication (NFC) zero power in Standby mode

When using the optional feature "NFC tap to power on", the base station is designed for 
zero power consumption in standby mode. It uses an NT3H1201 NTAG-I2C NFC forum 
passive tag. 

When this feature is enabled, there is no pinging to detect the presence of a mobile device 
on the charger pad. Instead, an NFC enabled mobile device, for example a phone, wakes 
up the base station via the NT3H1201. Power transfer takes place with a certified Qi 
mobile device.

To enable more functions such as Bluetooth pairing, smart advertisements, and 
connection handovers, the passive tag can be programmed with the NXP TagWriter 
application (see 

Section 3.9 “NFC functionality”

).

Содержание AN11524

Страница 1: ...XA6 NWP2081 Wireless Charging Qi mobile devices base station magnetic coupled power transfer Abstract This document illustrates how to create a Qi A6 wireless power base station It uses the NXQ1TXA6 c...

Страница 2: ...eserved Application note Rev 1 17 February 2015 2 of 54 Contact information For more information please visit http www nxp com For sales office addresses please send an email to salesaddresses nxp com...

Страница 3: ...inductive power The Qi system see Figure 1 comprises a base station or a transmitter TX pad and a mobile device or a compatible receiver RX such as a mobile phone To use the system the mobile device...

Страница 4: ...i certified and it complies with EMI regulation EN55022 and FCC part 18 The document is intended to provide engineers with real life practical design applications and get them started on the right not...

Страница 5: ...charger controller IC NWP2081 half bridge level shift controller IC NX2020 MOSFETs NT3H1201 NTAG I2C NFC forum tag AC 110 V 220 V DC 12 V power supply containing TEA1720B3T HV start up fly back contr...

Страница 6: ...efficiency of the evaluation board is shown using a standard off the shelf receiver System efficiency is measured as the ratio of output power of the receiver to the input power of the transmitter In...

Страница 7: ...1 17 February 2015 7 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board The function of the switch and push buttons as well as the meaning of the status LED is explained in the next subsectio...

Страница 8: ...NFC enabled phone switches on the 12 V system supply enabling zero power in standby mode Important The present generation of NFC phones only performs periodic NFC operations when the display of the p...

Страница 9: ...k to the NXP website When most NFC phones are put on the charger pad while the screen is active an automatic link to the NXP website is made Other content can be programmed into NTAG IC by using for e...

Страница 10: ...le N channel Trench MOSFET SOT1220 plastic thermal enhanced ultra thin small outline package no leads 6 terminals 9340 682 45115 BAS21 High voltage switching diodes SOT23 plastic surface mounted packa...

Страница 11: ...ic principle of inductively coupled power transfer An alternating current generated from the half bridge driver is passed through the base station coil It creates a magnetic field which induces a volt...

Страница 12: ...uation board block diagram aaa 014209 NFC TAG IF NXQ1TXA6 UI CTRL NXP component Optional NXP components for NFC control and zero standby power MONITOR HALF BRIDGE CONTROL CONTROLLER DEMODULATOR ASK DE...

Страница 13: ...NX2020N2 N channel Trench MOSFETs are the two key semiconductor components They drive the A6 type primary coil and series capacitance LC tank circuit at operating frequency between 115 kHz to 205 kHz...

Страница 14: ...to DC converter A DC to DC buck converter steps the 12 V input down to 3 3 V to supply the NXQ1TXA6 charging controller and other 3 3 V circuits A Richtek RT8295A DC to DC converter is used in the NXQ...

Страница 15: ...learly in the schematics so that they are not forgotten during procurement and production For example 68 nF C0G NP0 capacitor 100 k 1 tolerance resistor and 100 V rated components Certain critical com...

Страница 16: ...1 SEL2 13 EN_HB2 14 EN_HB3 SW1 ASEL3 PWR_ON 6 LED_G SCL SDA LP_VSUP EN_HB1 1 2 IS 2 3 4 EXPIO1 3V3 TESTIO TESTCLK SW1 PWM_HIN 1 2 3 4 TAG_FD 7 TESTCLK ISOUT AM 1 5 AML 1 5 NTC TESTIO measure power sup...

Страница 17: ...stage of coil 1 and current sense schematic aaa 015888 C211 68 nF COG 100 V C210 68 nF COG 100 V C217 100 nF C216 22 F C214 n c C213 n c 5 UC1_2 COIL1C COIL1T CL1C CL1T 1 2 3 4 GL NWP2081 R205 R206 1...

Страница 18: ...3 aaa 015889 C308 68 nF COG 100 V C307 68 nF COG 100 V C312 100 nF C311 22 F C310 5 6 nF COG 100 V C309 5 6 nF COG 100 V 5 UC2_2 COIL2C COIL2T CL2C CL2T 1 2 3 4 GL NWP2081 R304 R303 1 1 G301 G302 C30...

Страница 19: ...54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board Fig 10 Amplitude Shift Keying ASK envelope detector schematic aaa 015890 UC1_2 2 AML 1 AM 1 3V3 REMARK MAX VOLTAGE 100 V UC2_2 3 UC3_2 4 D501 BA...

Страница 20: ...V 2015 All rights reserved Application note Rev 1 17 February 2015 20 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board Fig 11 DC supply schematic aaa 015891 12V VIN BOOT TP601 3V3 SW FB COMP...

Страница 21: ...zer only when buzzer is needed DCDC when a DC to DC converter for 3 3 V is preferred LDO when LDO regulator for 3 3 V is preferred NFC when NFC is needed ZERO when zero power standby is needed also re...

Страница 22: ...X7R 10 C202 100 nF Standard C0603 FOD capacitor ceramic 50 V X7R 10 C203 100 nF Standard C0603 capacitor ceramic 50 V X7R 10 C205 100 nF Standard C0603 capacitor ceramic 50 V X7R 10 C206 22 F 1210 GR...

Страница 23: ...ceramic 50 V X7R 10 C407 68 nF C0G 1812 C4532C0G2A683J250KA TDK C1812 capacitor ceramic 100 V C0G 5 C408 68 nF C0G 1812 C4532C0G2A683J250KA TDK C1812 capacitor ceramic 100 V C0G 5 C409 NC 100V C0G Sta...

Страница 24: ...SOT23 High voltage switching diode D506 BAT54S BAT54S NXP Semiconductors SOT23 Schottky barrier double diodes D601 BAT54C BAT54C NXP Semiconductors SOT23 ZERO Schottky barrier double diodes J601 DC10...

Страница 25: ...n c Standard R0603 n c chip resistor 0 1 W 5 R119 180 R 1 Standard R0603 chip resistor 0 1 W 1 R201 10 k Standard R0603 chip resistor 0 1 W 5 R202 2 2 k Standard R0603 FOD chip resistor 0 1 W 5 R203 3...

Страница 26: ...0 1 W 1 R608 75 k 1 Standard R0603 DCDC chip resistor 0 1 W 1 R701 220 k Standard R0603 NFC chip resistor 0 1 W 5 R702 10 k Standard R0603 NFC chip resistor 0 1 W 5 R703 10 k Standard R0603 NFC chip...

Страница 27: ...S NX3008CBKS NXP Semiconductors SOT363 NFC 30 30 V 350 250 mA N P channel Trench MOSFET TEST101 M50 3600542 M50 3600542 Samtec 127_2R10_SMT Debug connector header SMT R A 1 27 mm 10P U101 NXQ1TXA6 NXQ...

Страница 28: ...ies using 136 nF for a charging coil further away from the charging pad As an example Figure 13 depicts the LC tank circuit of coil 1 which is the furthest from the interface surface The capacitance o...

Страница 29: ...ded but not populated in NXQ1TXA6 Evaluation Board They are located across the switching MOSFETs to allow tuning to reduce Electro Magnetic EM emission Capacitor snubber circuits must be placed close...

Страница 30: ...voltage 7 4 Configuration and voltage measurement circuits The inputs OPT1 and OPT2 are used for configuring the NXQ1TXA6 controller Input OPT1 is used to select the user interface LED and Buzzer con...

Страница 31: ...rance resistors in Configuration OPT0 and OPT1 and Voltage Sensing VSNS circuits 7 5 Thermal protection NTC201 provides temperature sensing which allows the controller option to sense the temperature...

Страница 32: ...with the parallel capacitor C704 Capacitor dielectric must be C0G NP0 type If the resonance frequency is too low after removing parallel capacitor C704 the 1 nF value of the series capacitors C705 an...

Страница 33: ...stack up applied in NXQ1TXA6 Evaluation Board is as follows 1 Layer 1 Component placement and signal trace 2 Layer 2 Clean uninterrupted ground 3 Layer 3 Signal trace 4 Layer 4 Ground and minimal rout...

Страница 34: ...neath NXQ1TXA6 right aaa 015899 2 RESET 3 SEL3 8 PWR_ON 9 LED_G 10 SCL 11 SDA 15 EN_HB1 16 LP_VSUP 17 PWM_HIN 18 TAG_FD 19 n c 21 ISENSE 22 ASK 23 CL_DET 24 NTC1 25 n c 26 VSNS 30 SEL1 31 RXD 32 TXD 7...

Страница 35: ...ea of the power ground plane Keep the current loops shown in green in Figure 22 compact to minimize radiation Place the decoupling capacitor C203 at the VDD supply pin of the NWP2081 U201 close to the...

Страница 36: ...pact and make sure the decoupling capacitors inductor and feedback components are close Use X7R capacitors of good quality for C605 and C609 8 5 Current sensing layout technique When dealing with very...

Страница 37: ...ction FOD The sense resistor R204 should have an accuracy of 1 or better tolerance and have a temperature stability of at least 200 PPM 8 6 EMC common mode filter The common mode filter L601 in Figure...

Страница 38: ...4 Ground and minimal routing trace if required 2 Separate system ground plane from power ground plane and tie them at only one point 3 Use only components with correct characteristics and ratings 4 Ti...

Страница 39: ...points in the design For trace in the figures the names of the corresponding schematic signal names are mentioned 9 1 Power stage Figure 30 shows the power stage behavior under a load condition of 1 2...

Страница 40: ...ehavior under a load of 5 W Notice that the frequency is lower for the 5 W power transfer compare to the 1 25 W power transfer in Figure 30 Depending on receiver characteristics the waveform on the co...

Страница 41: ...tors AN11524 NXQ1TXA6 Evaluation Board In Figure 32 the dead time behavior of the half bridge driver is visible in the waveform measured at the output of the driver stage CH1 PWM_HIN PWM input to half...

Страница 42: ...ary 2015 42 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board 9 2 ASK waveforms Figure 33 shows the ASK waveform visible on the charging coil voltage at spot Coil2C and the resulting output A...

Страница 43: ...NXQ1TXA6 Evaluation Board 9 3 Digital ping Figure 34 shows that a digital ping is performed on each coil at interval of 500 ms to detect the presence of a Qi receiver device The waveforms show the dig...

Страница 44: ...e CH 1 being 0 Volta in Figure 35 When an NFC field is applied to the charging pad by an NFC enabled phone the NFC TAG chip TAG_VOUT seen in CH 2 switches on the 12 V supply After the DC to DC convert...

Страница 45: ...ument is subject to legal disclaimers NXP Semiconductors N V 2015 All rights reserved Application note Rev 1 17 February 2015 45 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board 10 PCB layou...

Страница 46: ...n this document is subject to legal disclaimers NXP Semiconductors N V 2015 All rights reserved Application note Rev 1 17 February 2015 46 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board Fi...

Страница 47: ...in this document is subject to legal disclaimers NXP Semiconductors N V 2015 All rights reserved Application note Rev 1 17 February 2015 47 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board...

Страница 48: ...d in this document is subject to legal disclaimers NXP Semiconductors N V 2015 All rights reserved Application note Rev 1 17 February 2015 48 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board...

Страница 49: ...d in this document is subject to legal disclaimers NXP Semiconductors N V 2015 All rights reserved Application note Rev 1 17 February 2015 49 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board...

Страница 50: ...in this document is subject to legal disclaimers NXP Semiconductors N V 2015 All rights reserved Application note Rev 1 17 February 2015 50 of 54 NXP Semiconductors AN11524 NXQ1TXA6 Evaluation Board F...

Страница 51: ...ctors AN11524 NXQ1TXA6 Evaluation Board 11 Conclusion This document shows how to create a Qi A6 type wireless power base station with NXP NXQ1TXA6 charging controller and NWP2081 half bridge driver It...

Страница 52: ...onductors products and NXP Semiconductors accepts no liability for any assistance with applications or customer product design It is customer s sole responsibility to determine whether the NXP Semicon...

Страница 53: ...r circuits of coil 1 29 Fig 15 Current sense resistor 30 Fig 16 Amplitude Shift Keying ASK envelope detector 30 Fig 17 Configuration and voltage measurement 31 Fig 18 Temperature sensing circuit 32 Fi...

Страница 54: ...universal mains adapter 13 5 5 Current measurement 14 5 6 Bandgap reference voltage 14 5 7 DC to DC converter 14 5 8 Near Field Communication NFC zero power in Standby mode 14 6 Schematics and Bill O...

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