Evaluates: MAX3535E 19-0716 Rev 0 12/06 MAX3535E Evaluation Kit General Description Features The MAX3535E evaluation kit (EV kit) is a fully assem- Designed for 2500V Isolation RMS bled and tested PCB that contains a 2500V isolated RMS 1/8 RS-485 Unit Load RS-485/RS-422 transceiver with ESD protection. The EV kit circuit features a differential driver and one receiver. 1000kbps Full-Duplex RS-485/RS-422 The circuits receiver is a 1/8 unit load for the RS-485 Communication (Configurable for Half Duplex) bus and communicates up to 1000kbps. The MAX3535E +3.0V to +5.5VDC Input Range fail-safe circuitry and driver slew-rate features are demon- strated and easily reconfigured. Isolated V Output CC2 Additionally, the EV kit features an H-bridge DC-DC Center-Tapped, Full-Wave Rectifier Output converter to power the isolated section of the MAX3535E 420kHz Switching Frequency RS-485/RS-422 circuit. Input power to the circuit is supplied by a +3V to +5.5VDC source. This circuit uses a Undervoltage Lockout (UVLO) and Thermal full-wave rectifier on the unregulated output and provides Shutdown unregulated voltage to the MAX3535E internal, linear Low-Cost Integrated-FET H-Bridge Design low-dropout (LDO) regulator. Using an H-bridge design minimizes input ripple current and radiated noise. Fully Assembled and Tested Undervoltage lockout (UVLO) and thermal shutdown provide for a robust, isolated RS-485/RS-422 transceiver circuit and power supply. The surface-mount transformer provides up to 2500V galvanic isolation and the out- RMS put is powered from a center-tapped, full-wave rectifier circuit to reduce output voltage ripple. The isolated H-bridge DC-DC converter operation at 420kHz allows the use of ceramic-only output capaci- tors and a small transformer. Component List Ordering Information DESIGNATION QTY DESCRIPTION PART TEMP RANGE IC PACKAGE 10F 10%, 10V X7R ceramic MAX3535EEVKIT+ 0C to +70C* 28 Wide SO C1, C3 2 capacitors (1206) +Denotes a lead-free and RoHS-compliant EV Kit. Murata GRM31CR71A106K *This limited temperature range applies to the EV kit PCB only. 0.1F 10%, 25V X7R ceramic The MAX3535E IC temperature range is -40C to +85C. C2, C4 2 capacitors (0805) Murata GRM21BR71E104K 30V, 200mA S ch ottky d i ode ( S O T- 23) D1 1 Component Suppliers C entral S em i conduc tor C BAT54C JU1 1 3-pin header SUPPLIER PHONE WEBSITE JU2, JU3, JU4 3 2-pin headers C entral 631-435-1110 www.centralsemi.com Not installed, resistors (0805) S emicon duct or R1, R2 0 10k 1% resistor recommended HALO Electronics 650-903-3800 w w w.haloelec tron ics .com R3, R4 2 100k 5% resistors (0805) M urata Mfg . C o ., Ltd. 770-436-1300 www.murata.com 500H, 3kV 1CT:1:33CT turns RMS Note: Indicate that you are using the MAX3535E when contact- T1 1 transformer (6 pin) ing these component suppliers. HALO Electronics TGMR-340NA5RL U1 1 MAX3535EEWI+ (28-pin Wide SO) 4 Shunts (JU1JU4) 4 Rubber bumpers 1 PCB: MAX3535EEVKIT+ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.MAX3535E Evaluation Kit The MAX3535E fail-safe circuitry signals are also provid- Quick Start ed on the RO1 (receiver output) and RO2 (isolated receiv- Required Equipment er output) PC pads. Either pad gives a logic-high if A-B is One 5V, 1A current-limited power supply with built-in > -10mV, or if A-B floats or shorts. A logic-low is given if current meter A-B is < -200mV. Refer to the Fail Safe section and Table 3 in the MAX3535E IC data sheet for additional informa- One voltmeter tion on the fail-safe circuitry and operation. One logic signal generator The circuits input power is typically a +5VDC source, One oscilloscope or is operated from a +3V to +5.5VDC source with a corresponding reduction in the output voltage on the Procedure isolated side. The EV kit circuits DC source must pro- The MAX3535E EV kit is fully assembled and tested. vide at least 350mA of current, but can also be operat- Follow the steps below to verify board operation. ed at lower voltages consistent with the UVLO limit. Caution: Do not turn on the power supply until all con- nections are completed. The MAX3535E integrates a primary-side controller and H-bridge drivers. The device contains an on-board 1) Connect a voltmeter to the V and SGND PC CC2 oscillator, protection circuitry, and internal FET drivers pads. to provide up to 500mW of power to the primary of 2) Verify that a shunt is installed across pins 2-3 of transformer T1. jumper JU1 (receiver enabled). The MAX3535E driver slew rate is reconfigured using 3) Verify that a shunt is not installed across the pins of jumper JU2 on the EV kit. The slew rate can be config- jumper JU2 (fast slew rate). ured for 400kbps (slow) operation to minimize EMI radi- 4) Verify that a shunt is installed across the pins of ation or 1000kbps (fast). See the Slew-Rate Selection jumpers JU3 and JU4 (half duplex). section for configuring the slew rate. 5) Connect the +5V power supply to the V pad. The circuits H-bridge DC-DC converter powers the CC1 Connect the power supplys ground to the GND MAX3535E isolated section of the circuit. One of the pad. benefits of the easy-to-use H-bridge DC-DC converter topology is minimized input ripple current, and radiated 6) Turn on the power supply and verify that the volt- noise by the inherent balanced nature of the design, meter at V reads over +5V. CC2 with no interruption in the input current. UVLO and ther- 7) Apply a logic signal to the DI PCB pad and GND. mal shutdown provide for a robust isolated supply. Using an oscilloscope, verify the signal at the A-B, Thermal-shutdown circuitry provides additional protec- RO2, and RO1 output pads. tion against damage due to overtemperature condi- The +5V supply powering the MAX3535E EV kit must tions. The MAX3535E ICs UVLO provides controlled be current limited at 1A. turn-on while powering up and during brownouts. The surface-mount transformer provides up to Detailed Description 2500V galvanic isolation and the output is powered RMS The EV kit features a MAX3535E IC in a 28-pin wide SO from a center-tapped, full-wave rectifier circuit to surface-mount package and demonstrates the reduce output voltage ripple. The isolated H-bridge MAX3535E 2500V isolated RS-485/RS-422 trans- RMS DC-DC converter operation at 420kHz allows the use of ceiver with ESD protection. The circuits differential dri- ceramic-only output capacitors and a small trans- ver and receiver are configurable for full- or half-duplex former. The switching-frequency duty cycle is fixed at operation and can communicate up to 1000kbps. The 50% to control energy transfer to the isolated output circuit is a 1/8 unit load on the receivers bus. and to prevent DC current flow in the transformer. The EV kit features PCB pads to ease interfacing with The PCB is designed for 2500V isolation with 300 mils logic signals for the driver and receiver signals. On the spacing between the GND and SGND planes. Test nonisolated side, the DI pad is the driver input pad and points TP1 (GND) and TP2 (SGND) are provided on the the RO1 pad is the receiver-signal output pad. Resistor PCB for probing the respective ground plane, or to con- R3 pulls the DI pad up to V , and resistor R4 pulls CC1 nect the GND to SGND planes for nonisolated evalua- the DE pad up to V . On the isolated side, the RO2 CC1 tion of the circuit. pad is the receiver output. 2 Evaluates: MAX3535E