Epcom EPC9058 Quick Start Manual

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Development Board EPC9058 Quick Start Guide

EPC2110 High Frequency Class-E Wireless Power Amplier

Revision 1.0

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QUICK START GUIDE

Demonstration System EPC9058

DESCRIPTION

The EPC9058 is a high eciency, dierential mode Class-E amplier development board that can operate up to 15 MHz, including 6.78 MHz which is popular for wireless power. However, this board is not precongured for any particular frequency. The purpose of this development board is to simplify the evaluation process of class-E amplier technology using eGaN® FETs by allowing engineers to easily mount all the critical class-E components on a single board that can be easily connected into an existing system.

This board may also be used for applications where a low side switch is utilized. Examples include, and are not limited to, push-pull converters, current-mode Class D ampliers, common source bi-directional switch, and generic high voltage narrow pulse width applications such as LiDAR.

The amplier board features the 120 V rated EPC2110 eGaN FET. The amplier is set to operate in dierential mode and can be re-congured to operate in single-ended mode and includes the gate driver and logic supply regulator.

For more information on the EPC2110 eGaN FETs please refer to the datasheet available from EPC at www.epc-co.com. The datasheet should be read in conjunction with this quick start guide.

Table 1: Performance Summary (TA = 25°C) EPC9058

Symbol Parameter Conditions Min Max Units

Class-E Conguration 0 20 V

Main Supply Voltage

OUT

OSC

* Maximum current depends on die temperature – actual maximum current will be subject to switching frequency, bus voltage and thermals.

Range

Control Supply Input

Range

Switch Node Output

Current (each)

Oscillator Input

Threshold

Current Mode Class-D

Conguration

Push-Pull Conguration 0 52 V

Input ‘Low’ -0.3 1.5 V

Input ‘High’ 3.5 5 V

0 20 V

7 12 V

2* A

DETAILED DESCRIPTION

The Amplier Board (EPC9058)

Figure 1 shows the schematic of a single-ended, Class-E amplier with ideal operation waveforms where the amplier is connected to a tuned load such as a highly resonant wireless power coil. The amplier has not been congure due to the specic design requirements such as load resistance and operating frequency. The design equations of the specic ClassE amplier support components are given in this guide and specic values suitable for a RF amplier application can then be calculated.

Figure 2 shows the dierential mode Class-E amplier EPC9058 demo board power circuit schematic. In this mode the output is connected between Out 1 and Out 2. A block-wave external oscillator with 50 % duty cycle and 0 V – 5 V signal amplitude is used as a signal for the board. Duty cycle modulation is recommended only for advanced users who are familiar with the Class-E amplier operation and require additional eciency.

The EPC9058 is also provided with a 5 V regulator to supply power to the logic circutis and gate driver. Adding a 0 Ω resistor in position R90 allows the EPC9058 to be powered using a single-supply voltage; however in this conguration the maximum operating voltage is limited to between 7 V and 12 V.

Single-ended Mode operation

Although the default conguration is dierential mode, the demo board can be re-configured for single-ended operation by shorting out C74 (which disables only the drive circuit) and connecting the load between Out 1 and GND only (see gures 2 and 5 for details).

Class-E amplier operating limitations

The impact of load resistance variation is signicant to the performance of the Class-E amplier, and must be carefully analyzed to select the optimal design resistance.

EPC9058 amplier board.

The impact of load resistance (R

– Real part of Z

Load

) variation on the

Load

operation of the Class-E amplier is shown in gure 3. When operating a Class-E amplier with a load resistance (R

– Real part of Z

Load

) that is below the design value (see the waveform on the left of gure 3), the load tends to draw current from the amplier too quickly. To compensate for this condition, the amplier supply voltage is increased to yield the required output power. The shorter duration of the energy charge cycle leads to a signicant increase in the voltage to which the switching device is exposed. This is done in order to capture sucient energy and results in device body diode conduction during the remainder of the device o period. This period is characterized by a linear increase in device losses as a function of decreasing load resistance (R

When operating the Class-E amplier with a load resistance (R

Load

) that

Load

is above the design value (see the waveform on the right of gure 3), the load tends to draw insucient current from the amplier, resulting in an incomplete voltage transition. When the device switches there is a residual voltage across the device, which leads to shunt capacitance (C

+ Csh) losses. This period in the cycle is characterized by an expo-

OSS

nential increase in device losses as function of increasing reected load resistance.

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QUICK START GUIDE

Demonstration System EPC9058

Given these two extremes of the operating load resistance (R

Load

), the optimal point between them must be determined. In this case, the optimal point yields the same device losses for each of the extreme load resistance points and is shown in the lower center graph of gure 3. This optimal design point can be found through trial and error, or using circuit simulation.

Class-E amplier design

For this amplier only three components need to be specically designed; 1) the extra inductor (Le), 2) the shunt capacitor (Csh) and, 3) the selection of a suitable switching device. The RF choke (L

) value is less

RFck

critical and hence can be chosen or designed.

The design equations for the Class-E amplier have been derived by N. Sokal [1]. To simplify these equations, the value of QL in [1] is set to innity, which is a reasonable approximation in most applications within the frequency capability of this development board. The design needs to have a specic load resistance (R

) value and desired load power (P

Load

) that is used to begin the design, which then drives the values of the other components, including the magnitude of the supply voltage.

The Class-E amplier passive component design starts with the load impedance value (Z

) shown in gure 1. The reactive component of Z

Load

is tuned out using a series capacitor CS, which also serves as a DC block, resulting in R

. It is a common mistake to ignore the need for the DC

Load

block, where a failure to do so can yield a DC current from the supply through to the load, and lead to additional losses in several components in that path.

First, using the equations in gure 4, both the extra inductor Le (equation 2 and shunt capacitor (equation 3) values can be determined [2], [3]. The value of the shunt capacitor includes the C

of the switching device, which must be subtracted from the

OSS

calculated value to yield the actual external capacitor (Csh) value. To do this, rst the magnitude of the supply voltage (VDD) is calculated using equation 1, which in turn can be used to determine the peak device voltage (3.56 · VDD).

The RMS value of the peak device voltage is then used to determine the C

of the device at that voltage. This is the capacitance that will be

OSSQ

deducted from the calculated shunt capacitor to reveal the external shunt capacitor (Csh) value. The C integrating the C C

value is larger than the calculated shunt capacitance, the design

OSSQ

as function of voltage using equation 4. If the

OSS

of the device can be calculated by

OSSQ

cannot be realized for the load resistance specied and a new load resistance (R

Finally, the choke (L

) must be chosen.

Load

) can be designed using equation 5 and, in this case,

RFck

a minimum value is specied. Larger values yield lower ripple current, which can lead to a more stable operating amplier. A too-low value will lead to increased operating losses and change the mode of operation of the amplier. In some cases this can be intentional.

Here:

= Load Resistance [Ω]

Load

= Load Power [W]

Load

VDD = Amplier Supply Voltage [V]

f = Operating Frequency [Hz]

Le = Extra Inductor [H]

Csh = Shunt Capacitor [F]

= Output Capacitance of the FET [F]

OSS

= Charge Equivalent Device Output Capacitance [F]

OSSQ

(See gure 6 of the EPC2110 datasheet)

VDS = Drain-Source Voltage of the FET [V]

= RF Choke Inductor [H]

RFck

CS = Series Tuning Capacitor [F]

= Load Impedance [Ω]

Load

NOTE. For dierential mode amplier design details, please refer to the

application note ‘AN021: eGaN FETs for Low Cost Resonant Wireless

Power Applications’

[1] N.O. Sokal, “Class-E RF Power Ampliers,” QEX, Issue 204, pp. 9–20, January/ February 2001.

[2] M. Kazimierczuk, “Collector amplitude modulation of the Class-E tuned power amplier,” IEEE Transactions on Circuits and Systems, June 1984, Vol.31, No. 6, pp. 543–549.

[3] Z. Xu, H. Lv, Y. Zhang, Y. Zhang, “Analysis and Design of Class-E Power Amplier employing SiC MESFETs,“ IEEE International Conference on Electron Devices and Solid-State Circuits (EDSSC) 2009, 25–27 December 2009, pp 28–31.

QUICK START PROCEDURE

The EPC9058 amplier board is easy to set up to evaluate the performance of the eGaN FET in a class-E amplier application. Once the design of the passive components has been completed and installed, then the board can be powered up and tested.

1. Make sure the entire system is fully assembled prior to making electrical connections including an applicable load.

2. With power o, connect the main input power supply bus to J62 as shown in gure 5. Note the polarity of the supply connector. Set the voltage to 0 V.

3. With power o, connect the logic input power supply bus to J90 as shown in gure 5. Note the polarity of the supply connector. Set the voltage to between 7 V and 12 V.

4. Make sure all instrumentation is connected to the system. This includes the external oscillator to control the circuit.

5. Turn on the logic supply voltage.

6. Turn on the main supply voltage starting from 0 V, and increase to the desired value. Note operating conditions and in particular the thermal performance and voltage of the FETs to prevent overtemperature and over-voltage failure.

7. Once operation has been conrmed, observe the device voltage, eciency and other parameters on both the amplier and device boards.

8. For shutdown, please follow steps in the reverse order.

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QUICK START GUIDE

Capacitance

NOTE. When measuring the high frequency content switch-node, care must be taken to avoid long ground leads. An oscilloscope probe connection (preferred method) has been built into the board to simplify the measurement of the Drain-Source Voltage (shown in gure 6). The choice of oscilloscope probe needs to consider tip capacitance where this will appear in parallel with the shunt capacitance thereby altering the operating point of the amplier.

Pre-Cautions

The EPC9058 development board showcases the EPC2110 eGaN FETs in a class-E amplier application. Although the electrical performance surpasses that of traditional silicon devices, their relatively smaller size does require attention paid to thermal management techniques.

RFck

Demonstration System EPC9058

The EPC9058 development board has no current or thermal protection and care must be exercised not to over-current or over-temperature the devices. Excessively wide load impedance range variations can lead to increased losses in the devices. The operator must observe the temperature of the gate driver and eGaN FETs to ensure that both are operating within the thermal limits as per the datasheets. Always check operating conditions and monitor the temperature of the EPC devices using an IR camera.

V / I

3.56 x V

Load

50%

Time

Ideal waveforms

Figure 1: Single-ended, Class-E amplier with ideal operation waveforms.

RFck1

e1x

CQ1

Coil connection

e2x

CQ2

RFck2

Figure 2: EPC9058 power circuit schematic.

~6.5 x V

Body diode

V / IV / I

3.56 x V

V / I

~2 x V

+ Csh)

OSS

losses

conduction

50%

FETloss

50%

Time TimeTime

50%

Optimal design

Load_Design

< Design point

Load

Drives FET voltage rating

= Design point

Load

Figure 3: Class-E operation under various load conditions that can be used to determine the optimal design load resistance (R

> Design point

Load

Drives FET C

OSS

choice

load

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QUICK START GUIDE

Demonstration System EPC9058

Capacitance

VDD =

π (π

+ C

OSSQ

= C

OSSQ

RFck

DC Block

Load

RFck

OSS

OSSQ

Voltage

Load

32 π f

+ 4)

(π

4 f

Load

(π

(π2 + 4)

+ 4)

f R

Load

OSS

Load

(VDS)

Figure 4: Class-E amplier design process with equations.

7 V - 12 VDC

supply

Logic

(note polarity)

Single supply jumper

RF choke 1

0 V - 20 V

DCmax

VIN supply (note polarity)

Out A oscilloscope probe

Sh1

Sh2

Output 1 pad

Ground post

Ground pad output

External oscillator

Output 2 pad

Out B oscilloscope probe

RF Choke 2

Figure 5: Proper connection and measurement setup for the amplier board.

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QUICK START GUIDE

Demonstration System EPC9058

Figure 6: Proper measurement of the drain voltage.

Table 2: EPC9058 Bill of Materials

Item Qty Reference Part Description Manufacturer Part #

1 4 C1, C2, C73, C74 22 pF, 50 V Würth 885012005057 2 2 C10, C20 2.2 µF 100 V Taiyo Yuden HMK325B7225KN-T 3 1 C40 4.7 µF, 10 V Samsung CL05A475MP5NRNC 4 3 C41, C70, C71 100 nF, 16 V Würth 885012205037 5 3 C90, C91, C92 1 µF, 25 V Würth 885012206076 6 2 D70, D71 40 V 30 mA Diodes Inc. SDM03U40 7 1 GP1 .1" Male Vert. Würth 61300111121 8 1 J62 .156" Male Vert. Würth 645002114822

9 2 J70, J90 .1" Male Vert. Würth 61300211121 10 1 Q1 120 V, 3.4 A, 60 mΩ EPC EPC2110 11 2 R11, R21 2.2 Ω Yageo RC0402JR-072R2L 12 2 R70, R71 0 Ω Samsung RC1005J000CS 13 1 R73 10 kΩ Yageo RC0402FR-0710KL 14 1 R74 10 kΩ Panasonic ERJ-2GEJ103X 15 1 R90 0 Ω (EMPTY ) Stackpole RMCF0603ZT0R00 16 1 U40 100 V eGaN Driver Texas Instruments LM5113TM 17 1 U70 2 In NAND Fairchild NC7SZ00L6X 18 1 U71 2 In AND Fairchild NC7SZ08L6X 19 1 U90 5.0 V 250 mA DFN Microchip MCP1703T-5002E/MC

Table 3: Optional Components

Item Qty Reference Part Description Manufacturer

1 2 CQ1, CQ2 Capacitor size 1111 Designed for Johanson

2 2 L10, L20 Inductor 13 x 13 mm Designed for Würth

3 2 L11, L21 Inductor 6.9 x 6.9 mm Designed for Würth

4 2 Le11, Le21 Coil size 2929SQ Designed for CoilCraft

5 2 Le12, Le22 Coil size 2222SQ Designed for CoilCraft

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QUICK START GUIDE

Demonstration System EPC9058

Vsup

7.5VDC

- 12VDC

Logic Supply Regulator

V7in

Vsup

Main Supply

Vsup

2.2 Ω

1 2

R11

1 2

R21

GRH GRL

5 V

GLH GLL

Gate Driver

U40 LM5113TM

L_Sig

R_Sig

LOGIC

SDM03U40

40 V, 30 mA

D71

5 V

Deadtime Left

Deadtime Right

Oscillator input

U70 NC7SZ00L6X

5 V

OSC

GRH GRL

GL L

GLH

TBD

L10

TBD

L20

OSC

Logic

Supply

Vsup

Single Supply Conguration

TBD

CQ2

TBD

CQ1

V7in

OutA

OutB

2.2 μF, 100 V

C20

2.2 μF , 100 V

C10

TBD

Le11

TBD

Le12

TBD

Le21

TBD

Le22

TBD

L21

SDM03U40

40 V, 30 mA

D70

U71 NC7SZ00L6X

0 Ω

1 2

R90

Out1

Out2

GND

.1" Male Vert.

1 2

J90

5VV7in

MCP1703T-5002E/MC

5.0 V 250 mA DFN

OUT

GN DINGN D

U90

nSD

5 V

10 k

R74

.1" Male Vert.

1 2

J70

4.7 μF, 10 V

C40

1 2

R70

1 2

R71

10 k

R73

.1" Male Vert.

GP1

Ground Post

ProbeHole

PH1

ProbeHole

PH2

.156" Male Vert.

J62

100 nF, 16 V

C70

100 nF, 16 V

C71

100 nF, 16 V

C41

22 pF, 50 V

C73

22 pF, 50 V

C74

1 μF, 25 V

C90

1 μF, 25 V

C91

1 μF, 25 V

C92

EPC2110

Figure 7: EPC9058 Class-E amplier schematic.

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For More Information:

Please contact [email protected] or your local sales representative

Visit our website:

www.epc-co.com

Sign-up to receive EPC updates at bit.ly/EPCupdates or text “EPC” to 22828

EPC Products are distributed through Digi-Key.

www.digikey.com

Demonstration Board Warning and Disclaimer

The EPC9058 board is intended for product evaluation purposes only and is not intended for commercial use. Replace components on the Evaluation Board only with those parts shown on the parts list (or Bill of Materials) in the Quick Start Guide. Contact an authorized EPC representative with any questions.

This board is intended to be used by certied professionals, in a lab environment, following proper safety procedures. Use at your own risk.

As an evaluation tool, this board is not designed for compliance with the European Union directive on electromagnetic compatibility or any other such directives or regulations. As board builds are at times subject to product availability, it is possible that boards may contain components or assembly materials that are not RoHS compliant. Ecient Power Conversion Corporation (EPC) makes no guarantee that the purchased board is 100% RoHS compliant.

The Evaluation board (or kit) is for demonstration purposes only and neither the Board nor this Quick Start Guide constitute a sales contract or create any kind of warranty, whether express or implied, as to the applications or products involved.

Disclaimer: EPC reserves the right at any time, without notice, to make changes to any products described herein to improve reliability, function, or design. EPC does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights, or other intellectual property whatsoever, nor the rights of others.