MAX16974EVKIT+

19-5661; Rev 0; 12/10 MAX16974 Evaluation Kit Features The MAX16974 evaluation kit (EV kit) provides a proven design to evaluate the MAX16974 high-voltage, 2.2MHz, 2A automotive step-down controller with low operating current. It is designed to operate with 3.5V to 28V input voltages, while using only 35µA quiescent current at no load. The switching frequency is adjustable from 220kHz to 2.2MHz and the output voltage is pin selectable at 5V fixed or 1V to 10V adjustable. This EV kit is initially set up to operate at 2.2MHz with a 5V output. S Wide 3.5V to 28V DC Supply Range The EV kit PCB comes with a MAX16974AUE/V+ installed. +Denotes lead(Pb)-free and RoHS compliant. S 42V Input Transient Tolerance S Proven PCB Layout S Fully Assembled and Tested Ordering Information PART TYPE MAX16974EVKIT+ EV Kit Component List DESIGNATION QTY CBST 1 0.1µF Q10%, 6.3V X5R ceramic capacitor (0402) TDK C1005X5R0J104K CCOMP1 1 5600pF Q10%, 50V X7R ceramic capacitor (0603) Murata GRM188R71H562K CCOMP2 0 Not installed, 120pF Q5%, 50V C0G ceramic capacitor (0603) Murata GRM1885C1H121J CCRES 1 CFB1 CIN1 CIN2, CIN3 CIN4, CIN5 COUT, COUT2 CSNUB DESCRIPTION DESIGNATION QTY DESCRIPTION CVL 1 2.2µF Q10%, 10V X7R ceramic capacitor (0603) Murata GRM188R71A225K D1 1 3A, 60V Schottky diode Diodes Inc. B360B JU1 1 3-pin header JU2, JU7 0 Not installed, 0I jumpers (0603) JU3, JU6, RTEST 3 0I Q5% resistors (0603) 100pF Q5%, 50V C0G ceramic capacitor (0603) Murata GRM1885C1H101J L1 1 4.7µH Q20%, 2.8A, 20mI inductor (7.0mm x 7.5mm) Panasonic ETQP5M4R7YFM 0 Not installed, ceramic capacitor (0603) LX 0 Not installed, multipurpose test point 1 47µF Q20%, 50V electrolytic capacitor (D8) Panasonic EEE-FK1H470XP 2 0.1µF Q10%, 50V X7R ceramic capacitors (0603) Murata GRM188R71H104K RCOMP 1 20kI Q1% resistor (0603) RFB1, RFB2, RFB3 0 Not installed, resistors (0603) RFOSC 1 12.1kI Q1% resistor (0603) RFSYNC 1 20kI Q5% resistor (0603) RRESB 1 10kI Q5% resistor (0603) 2 4.7µF Q10%, 50V X7R ceramic capacitors (1210) Murata GRM32ER71H475K RSNUB 0 Not installed, 3I Q5% resistor (0603) U1 1 2 22µF Q20%, 10V X7R ceramic capacitors (1210) Murata GRM32ER71A226K High-voltage automotive stepdown converter (16 TSSOP-EP*) Maxim MAX16974AUE/V+ — 1 Shunts Not installed, 1000pF Q10%, 50V X7R ceramic capacitor (0603) Murata GRM188R71H102K — 1 PCB: MAX16974 EVALUATION KIT+ 0 *EP = Exposed pad. /V denotes an automotive qualified part. ________________________________________________________________ Maxim Integrated Products   1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Evaluates: MAX16974 General Description Evaluates: MAX16974 MAX16974 Evaluation Kit Component Suppliers SUPPLIER PHONE WEBSITE Diodes Incorporated 805-446-4800 www.diodes.com Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com Panasonic Corp. 800-344-2112 www.panasonic.com TDK Corp. 847-803-6100 www.component.tdk.com Note: Indicate that you are using the MAX16974 when contacting these component suppliers. Quick Start • MAX16974 EV kit Recommended Equipment • 12V at 2A DC power supply • Digital voltmeter (DVM) External Clock Input (FSYNC) The IC synchronizes to an external clock signal applied at FSYNC. The signal at FSYNC must have a 10% higher frequency than the internal clock period for proper synchronization. Output-Voltage/RESET Threshold Resistive-Divider Network • 2A DC load (2.5I, 10W) Procedure The EV kit is fully assembled and tested. Follow the steps below to verify board operation: 1) Verify that all jumpers (JU1, JU2, JU3, JU6, and JU7) are in their default positions, as shown in Table 1. 2) Connect the DVM between the VOUT and GND pads. 3) Connect the load between the VOUT and GND pads. 4) Connect the power supply between the EXT_VBAT and GND pads. The output voltage of the IC can be programmed between 1V and 10V. Although the IC’s output voltage and reset threshold can be set individually, the EV kit supports the use of a combined resistive-divider network to set the desired output voltage and the reset threshold using three resistors (RFB1, RFB2, and RFB3). Use the following formula to determine the RFB3 of the resistivedivider network: RFB3 = (RFB1+RFB2 +RFB3) × VREF /VOUT 5) Enable the 12V power supply. where VREF = 1V and VOUT is the desired output voltage. 6) Verify that VOUT = 5V. RFB2 = ((RFB1+RFB2 +RFB3) × VREF_RES /VRES ) − RFB3 7) Verify that RESB is high. Detailed Description of Hardware The MAX16974 EV kit provides a proven layout for the MAX16974 IC. The EV kit is designed to fully demonstrate the functionality of the IC as follows: • Verify output-voltage regulation • Verify power-good behavior and reset-threshold selection • Easy programmability of different output voltages between 1V and 10V • Startup and shutdown performance • Current-limit performance The following detailed descriptions enable the user to program the EV kit per application requirements. where VREF_RES is 1.2V (refer to the Electrical Characteristics section in the MAX16974 IC data sheet) and VRES is the desired reset threshold in volts. The precision of the reset-threshold function is dependent on the tolerance of the resistors used for the divider. Refer to the MAX16974 IC data sheet for details. Some applications require the addition of a compensation capacitor at CFB1. Contact the factory for applications assistance. The 0I resistors at JU3 and JU6 must be moved to locations JU2 and JU7 to enable the combined resistivedivider network. As shipped from the factory, the 0I resistors are installed at JU3 and JU6, so that FB is tied to VL and RESETI is tied to ground, selecting the factory settings. 2   _______________________________________________________________________________________ MAX16974 Evaluation Kit Reset-Timeout Selection The CRES pin of the IC is for programming the powergood delay for the IC. The internal threshold of the CRES comparator is 1.25V. The CRES pin sources approximately 10µA current. Placing a capacitor (CCRES) from CRES to GND programs the delay time of the powergood indicator. Output-Voltage Selection Contact the factory for assistance in selecting components for other output voltages. Table 1. Jumper Descriptions (JU1, JU2, JU3, JU6, JU7) JUMPER SIGNAL JU1 EN JU2 FB SHUNT POSITION EN is tied to VSUP (battery input); normal operation. 2-3 EN is tied to GND; shutdown. 0I jumper installed Open* JU3 FB JU6 RESETI 0I jumper installed* Open 0I jumper installed* Open JU7 RESETI DESCRIPTION 1-2* 0I jumper installed Open* Output voltage is determined by RFB1, RFB2, and RFB3. OUT regulates FB to 1.00V at the RFB2/RFB3 junction. JU3 must be open. JU3 should be installed. See the JU3 description. FB is tied to BIAS; the output voltage is preset to 5V. JU2 must be open. JU2 should be installed. See the JU2 description. RESETI is tied to GND; the reset threshold is preset to 90% of VOUT. JU7 must be open. JU7 should be installed. See the JU7 description. Reset threshold is determined by RFB1, RFB2, and RFB3. Reset occurs when RESETI drops down to 1.2V. JU6 must be open. JU6 should be installed. See the JU6 description. *Default position. _______________________________________________________________________________________   3 Evaluates: MAX16974 The RES signal is asserted when RESETI is below 1.2V. The RFB1, RFB2, and RFB3 values should be chosen to set RESETI = 1.2V when the OUT voltage is too low. The recommended resistor-divider bias current is 50FA. Evaluates: MAX16974 MAX16974 Evaluation Kit Figure 1. MAX16974 EV Kit Schematic 4   _______________________________________________________________________________________ MAX16974 Evaluation Kit Figure 2. MAX16974 EV Kit Component Placement Guide— Component Side Figure 3. MAX16974 EV Kit PCB Layout—Component Side 1.0” Figure 4. MAX16974 EV Kit PCB Layout—Ground Layer 2 _______________________________________________________________________________________   5 Evaluates: MAX16974 1.0” 1.0” Evaluates: MAX16974 MAX16974 Evaluation Kit 1.0” Figure 5. MAX16974 EV Kit PCB Layout—Layer 3 1.0” Figure 6. MAX16974 EV Kit PCB Layout—Solder Side 1.0” Figure 7. MAX16974 EV Kit Component Placement Guide— Solder Side 6   _______________________________________________________________________________________ MAX16974 Evaluation Kit REVISION NUMBER REVISION DATE 0 12/10 DESCRIPTION Initial release PAGES CHANGED — Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ©  2010 Maxim Integrated Products 7 Maxim is a registered trademark of Maxim Integrated Products, Inc. Evaluates: MAX16974 Revision History