Converter Topology. Features. General Description. Component List

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1 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward General Description The MAX9 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that contains a peak-current-mode controller for an active-clamp forward regulator. The EV kit is configured for an isolated.v DC output voltage that can supply up to A of current. The input voltage range is from V DC to V DC. The EV kit demonstrates low quiescent current and efficiency up to 9.%. High efficiency is achieved by using an active-clamp forward converter topology, with self-driven synchronous secondary MOSFETs on the output side. The EV kit is configured to operate at a 0kHz switching frequency. The surface-mount transformer has a bias winding to power the IC after startup. An optocoupler along with the transformer provide galvanic isolation between input and output, up to 000V RMS. Warning: The EV kit is designed to operate with high voltages. Dangerous voltages are present on this EV kit and on the equipment connected to it. Users who power up this EV kit or the power sources connected to it must be careful to follow safety procedures appropriately to work with high-voltage electrical equipment. Under severe fault or failure conditions, this EV kit may dissipate large amounts of power, which could result in the mechanical ejection of a component or of component debris at high velocity. Operate this EV kit with care to avoid possible personal injury. Component List DESIGNATION QTY DESCRIPTION C C 00pF ±0%, V XR ceramic capacitor (00) AVX 00C0MATA µf ±0%, 00V aluminum electrolytic capacitor (mm diameter) Panasonic EEEFKA0P Features V DC to V DC Input Range Isolated Output Voltage:.V DC at A Galvanic Isolation Up to 000V RMS 0kHz Switching Frequency Efficiency Up to 9.% Active-Clamp Forward Proven PCB Layout Fully Assembled and Tested Ordering Information appears at end of data sheet. DESIGNATION QTY DESCRIPTION C C, C 0µF ±0%,.V aluminum electrolytic capacitor (.mm x.mm x.mm) SANYO TPF0M9L µf ±0%,.V XR ceramic capacitors (0) Murata GCMER0JK C.µF ±0%, 00V XR ceramic capacitor (0) Murata GRMERAK C, C0.µF ±0%, 0V XR ceramic capacitors (0) Murata GRMCRHK 9-0; Rev ; /

2 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward Component List (continued) DESIGNATION QTY DESCRIPTION C, C 0.µF ±0%, V XR ceramic capacitors (00) Murata GRMREK DESIGNATION QTY DESCRIPTION N 0V,.A n-channel MOSFET ( SO) Fairchild FDS C9 C0 C C 0 C, C 0 C C C C9 D D L L N, N µf ±0%, V XR ceramic capacitor (00) Murata GRM9RE0K nf ±0%, 0V XR ceramic capacitor (00) TDK C0XREK 0.0µF ±0%, V XR ceramic capacitor (00) Murata GRMREK Not installed, ceramic capacitor short (PCB trace) Not installed, ceramic capacitors (00).nF ±0%, 0V XR ceramic capacitor (00) TDK C0XRHK 000pF ±0%, V XR ceramic capacitor (00) Murata GRMRE0K 00nF ±0%, V XR ceramic capacitor (00) Murata GRMRC0K nf ±0%, V XR ceramic capacitor (00) Murata GRMREK 00V, 00mA fast-switching diodes (SOD) Diodes Inc. NW--F 0mH, 0mA inductor (.mm x.mm) API Delevan SDS0R-0M.µH,.A inductor Coilcraft SER0-ME V, A n-channel MOSFETs ( PG-TDSON) Infineon BSC00NELS P -0V, -0mA p-channel MOSFET ( SOT) Vishay Siliconix SiDS-T-GE R kω ±% resistor (00) R, R 0Ω ±% resistors (00) R9, R 0Ω ±% resistors (00) R.9kΩ ±% resistor (00) R.MΩ ±% resistor (00) R, R 0kΩ ±% resistors (00) R.kΩ ±% resistor (00) R 0kΩ ±% resistor (00) R0 Ω ±% resistor (00) R, R 9.9kΩ ±% resistors (00) R 0kΩ ±% resistor (00) R, R, R0 0 Not installed, resistors (00) R 0Ω ±% resistor (00) R.kΩ ±% resistor (00) R9 00Ω ±% resistor (00) R 0.Ω ±% resistor (0) Panasonic ERJ-BWFR00V R 0kΩ ±% resistor (00) R kω ±% resistor (00) T U U U *EP = Exposed pad. 00µH,.A, :0.:0. transformer (EFD0) Coilcraft MA-BL Peak-current-mode, active-clamp forward PWM controller ( TQFN-EP*) Maxim MAX9ATE+ Phototransistor (PIN, SO) Avago ACPL--AE.V 0.% shunt regulator ( SOT) Diodes Inc. TLVBFTA PCB: MAX9 EVALUATION KIT Maxim Integrated

3 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward Component Suppliers SUPPLIER PHONE WEBSITE API Delevan AVX Corporation Coilcraft, Inc Diodes Incorporated Fairchild Semiconductor -- Infineon Technologies AG Murata Electronics North America, Inc Panasonic Corp SANYO Electric Co., Ltd TDK Corp Vishay Note: Indicate that you are using the MAX9ATE when contacting these component suppliers. Quick Start Required Equipment MAX9 EV kit V to V DC power supply Electronic load Voltmeter Warning: Do not turn on the power supply until all connections are completed. Wear protective eye gear at all times. Do not touch any part of the circuit with bare hands or conductive materials when powered up. Make sure all high-voltage capacitors are fully discharged before handling. Allow minutes after disconnecting input power source before touching circuit parts. Setup and Test Procedure The EV kit is fully assembled and tested. Follow the steps below to verify board operation: ) Connect the positive lead of the DC voltmeter to the VOUT PCB pad. ) Connect the negative lead of the DC voltmeter to the PGND0 PCB pad. ) Set the DC power-supply output to V. Disable the power supply. ) Set the electronic load in constant-current (CC) mode. Disable the electronic load. ) Connect the power-supply positive terminal to the INPUT PCB pad. ) Connect the power-supply negative terminal to the PGND PCB pad. ) Connect the electronic load across the VOUT and PGND0 PCB pads. ) Enable the power supply. 9) Verify that VOUT is.v throughout the input voltage range of V DC to V DC. 0) Enable the electronic load. ) Verify that VOUT is.v throughout the output current range of 0 to A. Detailed Description of Hardware The MAX9 EV kit is a wide input voltage range, isolated,.w output power, active-clamp forward converter, configured for a.v DC, A output. A bias winding in the transformer is used to power the MAX9 during normal operation. The secondary winding provides.v DC output that can supply up to A. This EV kit uses the MAX9ATE in a -pin TQFN package with exposed pad, peak-current-mode, and pulse-width modulating (PWM) controller. This PWM controller varies the duty cycle to compensate for the variation in input voltage and the output load current to maintain constant output voltage. The duty cycle determines the on/off duration of the main (N) and auxiliary (P) MOSFETs. The P MOSFET functions as an active-clamp switch that implements the active-clamp transformer reset topology in forward converters. The two MOSFETs are used as switches to control the current through the primary winding of the transformer (T). Maxim Integrated

4 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward The duty cycle is controlled by the feedback loop consisting of voltage-divider resistors (R, R), shunt regulator (U), optocoupler (U), and the error amplifier and current-mode PWM comparator inside the IC. This network chain provides isolated voltage mode feedback, regulating the output voltage to.v ±% with up to 000V RMS galvanic isolation. Current Limit The IC features current limiting in the transformer s primary side by monitoring peak current through the sense resistor (R). R programs the maximum peakcurrent-limit setting. The IC turns off its internal switch when the peak current reaches the current limit. Use the following equation to calculate the value of R: 0 R= m Ω,. IPRI_PEAK where I PRI_PEAK is the maximum operational peak current in the primary side of the transformer in amps, and R is in mω. Undervoltage Lockout and Overvoltage Protection The EV kit features an input UVLO and OVI circuit that prevents operation below the programmed input supply startup voltage and above the overvoltage threshold. Resistors R, R, and R set the undervoltage and overvoltage thresholds. The circuit undervoltage and overvoltage thresholds are set at V DC (typ) and 0.V DC (typ), respectively. To reconfigure the UVLO and OVI voltages, refer to the Startup Voltage and Input Overvoltage Protection Setting (EN/UVLO, OVI) section in the MAX9/MAX99 IC data sheet. EN/UVLO and OVI PCB pads are available for monitoring the voltages present at the respective inputs. Soft-Start The EV kit provides an option to configure the circuit soft-start period. Capacitor C configures the soft-start time (t SS ) to ms. To reconfigure the soft-start time to a different value, use the following equation to choose a new C capacitor: 0 t C = ss nf VCOMP. Slope Compensation The EV kit operates at a maximum duty cycle of %. A minimum amount of slope signal is added to the sensed current signal, even if the operating duty cycle is below 0%, to provide stable, jitter-free operation. The EV kit is configured for default minimum slope with the SLOPE pin left unconnected. To reconfigure the slope compensation to a different value, use the following equation to choose a new R0 resistor: SE RSLOPE = k Ω,. where R SLOPE is in kω and S E is in mv/µs. Switching Frequency The EV kit switching frequency is set to 0kHz by resistor R. To configure the IC s switching frequency to a different value, between 00kHz and MHz, use the following equation to choose a new R resistor: 0 0 R = Ω, fsw where f SW is in Hz and R is in Ω. Frequency Dithering The EV kit switching frequency can be dithered in a range of ±0% to enable spread-spectrum operation. There are two specifications for the frequency dithering: frequency (how often) of dithering, and amount (how much) of dithering. Capacitor C configures the dither frequency using the following equation:. C = nf, fdither where f DITHER is in khz and C is in nf. A dither frequency f DITHER = khz is recommended. Resistors R and R configure the amount of dithering in percentage (%) of the switching frequency using the following equation: R %DITHER =, R where t SS is in ms, V COMP is the steady-state COMP voltage (V COMP,MAX =.V), and C is in nf. Maxim Integrated

5 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward The EV kit is shipped with the frequency dithering disabled, with the DITHER/SYNC pin shorted to SGND through PCB trace. To set the desired frequency dither, cut the PCB trace to place capacitor C and install resistor R with the appropriate values. The DITHER/ SYNC PCB pad is available for monitoring the signal at the DITHER/SYNC pin. Dead Time The EV kit provides an option to configure the dead time between the main and AUX output pulses. Resistor R configures the dead time (t DT ) to 0ns. To reconfigure the dead time to a different value, use the following equation to choose a new R resistor: R = 0. tdt k Ω, where t DT is in ns and R is in kω. EV Kit Performance Results 00 EFFICIENCY CURVES TRANSIENT RESPONSE 90 0 EFFICIENCY (%) I LOAD A/div V OUT (AC) 00mV/div OUTPUT CURRENT (A) V IN = V V IN = V V IN = V 00µs/div Figure. Efficiency Curves Figure. Transient Response.0..0 LOAD AND LINE REGULATION V IN = V V IN = V V IN = V BODE PLOT OUTPUT VOLTAGE (V) OUTPUT CURRENT (A) BANDWIDTH = 0.kHz PHASE MARGIN = PHASE /div GAIN 0dB/div Figure. Load and Line Regulation Figure. Bode Plot Maxim Integrated

6 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward Figure. MAX9 EV Kit Schematic Maxim Integrated

7 Maxim Integrated MAX9 Evaluation Kit MAX9 in Active-Clamp Forward Figure. MAX9 EV Kit Component Placement Guide Component Side Figure. MAX9 EV Kit PCB Layout Component Side

8 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward.0 Figure. MAX9 EV Kit PCB Layout Solder Side Maxim Integrated

9 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward Ordering Information PART MAX9EVKIT# #Denotes RoHS compliant. TYPE EV Kit Maxim Integrated 9

10 MAX9 Evaluation Kit MAX9 in Active-Clamp Forward Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 / Initial release / Updated R, R component values, For pricing, delivery, and ordering information, please contact Maxim Direct at --9-, or visit Maxim Integrated s website at. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. 0 Maxim Integrated Products, Inc. 0