MAX8654 Evaluation Kit. Evaluates: MAX8654/MAX8688

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1 9-064; Rev ; 0/08 MAX8654 Evaluation Kit General Description The MAX8654 evaluation kit (EV kit) is a fully assembled and tested PCB that demonstrates the capabilities of the MAX8654 integrated 8A step-down regulator. The EV kit generates a.v output voltage at load currents up to 8A from a 4.5V to 4V input voltage range. The MAX8654 switches at 500kHz and provides over 9.4% efficiency with the supplied components. Component Suppliers SUPPLIER PHONE WEBSITE M ur ata E l ectr oni cs N orth Am er ica, Inc w ww.m ur ata- nor tham er ica.com Taiyo Yuden TDK Corp TOKO America, Inc Note: Indicate that you are using the MAX8654 when contacting these component suppliers. DESIGNATION QTY DESCRIPTION CA, CB, CC C C, C C4 C5A, C5B, C5C C6 C7 MAX8654 Circuit 0µF ±0%, 6V X5R ceramic capacitors (06) Taiyo Yuden EMK6BJ06M µf ±0%, 6.V X5R ceramic capacitor (040) Murata GRM55R60J05K 0.0µF ±0%, 50V X7R ceramic capacitors (040) Murata GRM55R7H0K 0.µF ±0%, 6V X7R ceramic capacitor (060) TDK C608X7RC4M µf ±0%, 6.V X5R ceramic capacitors (06) TDK C6X5R0J6M 6800pF ±0%, 50V X7R ceramic capacitor (040) Murata GRM55R7H68KA88 0.0µF, 0V X7R ceramic capacitor (040) Murata GRM55R7CCKA0I Features Internal 6mΩ RDS(ON) MOSFETs Guaranteed 8A Output Current Adjustable Over-Current Protection, 6A to A ±% Output Accuracy Over Load, Line, and Temperature Operates from 4.5V to 4V Supply Adjustable Output from 0.6V to 0.85 x V IN Soft-Start Reduces Inrush Supply Current 50kHz to.mhz Adjustable Switching or SYNC Input Compatible with Ceramic, Polymer, and Electrolytic Output Capacitors SYNCOUT Synchronizes nd Regulator 80 Out-of-Phase 6-Pin 6mm x 6mm TQFN Package Ordering Information PART TEMP RANGE IC PACKAGE 6 TQFN MAX8654EVKIT+ 0 C to +70 C (6mm x 6mm) +Denotes a lead-free and RoHS-compliant EV kit. Component Lists DESIGNATION QTY DESCRIPTION C8 C9 C0 C C C4, C5 C pF, 50V C0G ceramic capacitor (040) Murata GRM555CHDTADI 4.7µF ±0%, 6V X5R ceramic capacitor (060) Murata GRMBR6C475K 0.µF,6V Y5R ceramic capacitor (040) Taiyo Yuden EMK05BJ4MV-F 470pF ±0%, 50V X7R ceramic capacitor (040) Murata GRM55R7H47K 0.µF ±0%, 0V X7R ceramic capacitor (040) Murata GRM55R6A04K 0.µF ±0%, 50V X5R ceramic capacitors (0805) Taiyo Yuden UMKBJ4M Not installed, 0.0µF ±0%, 5V X7R ceramic capacitor (040) Murata GRM55R7E0K Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at , or visit Maxim s website at

2 Component Lists (continued) DESIGNATION QTY DESCRIPTION JP JP7, JP9 JP 0 Not installed JU, JU, JU4 -pin headers JU -pin header L µh, 7.9mΩ, A inductor (7.4mm x 6.7mm x mm) TOKO FDV060-R0M R, R, R0 00kΩ ±% resistors (040), lead free R.5kΩ ±% resistor (040), lead free R4 Ω ±% resistor (040), lead free R5 5Ω ±5% resistor (040), lead free R6 475Ω ±% resistor (040), lead free R7 75kΩ ±% resistor (040), lead free R8.Ω ±% resistor (06), lead free R9, R kω ±% resistors (040), lead free R 0Ω ±% resistor (040), lead free U 8A step-down regulator Maxim MAX8654ETX+ Shunts PCB: MAX8654 Evaluation Kit+ DESIGNATION QTY DESCRIPTION C0, C0, C0, C05, C06, C07 0 C04 0 C08 0 MAX8688 Circuit Not Installed 00nF ±0%, 50V X7R ceramic capacitors (060), open Murata GRM88R7H04K µf ±0%, 0V X5R ceramic capacitor (060), open Murata GRM88R6A05K.µF ±0%, 0V X5R ceramic capacitor (060), open Taiyo Yuden LMK07BJ5K C09 0 Ceramic capacitor, open C µF ±0%, 0V X5R ceramic capacitor (060), open Murata GRM88R6A474K D 0.V 50mW zener diode (SOT), open Central Semiconductor CMPZ460 JP0 0 4-pin header, open JP0, JP0, JP04 0 -pin header, open R9 0 00kΩ resistor, open MAX8688 Circuit Not Installed MAX8654 Circuit DESIGNATION QTY DESCRIPTION R0, R04, R06, R08, 0 Resistors, open R09, R4 R0 0 0Ω resistor (040) R0 0 kω ±% resistor (040), open R05, R07, R0 0 kω ±% resistors (040), open R 0 909Ω ±5% resistor (060), open R 0 00kΩ ±% resistor (040), open R5 0 0kΩ ±% resistor (040), open R6, R7 0 00Ω ±% resistors (040), open U0 0 MAX8688+, open U0 0 AT4C0A-0TSU-.8, open Quick Start Recommended Equipment Before beginning, the following equipment is needed: Up to V at +A DC power supply or battery Digital multimeter (DMM) Up to 8A load Ammeter (optional) Procedure The MAX8654 EV kit is fully assembled and tested. Follow the steps below to verify board operation. Caution: Do not turn on the power supply until all connections are made. ) Preset the DC power supply to V. Turn off the power supply. ) Ensure that there is a shunt on JU and JU. ) Ensure that there is a shunt on pins - of JU. 4) Connect the positive lead of the power supply to the VIN pad and connect the negative lead of the power supply to the GND pad on the EV kit. 5) Connect the positive lead of the DMM to the VOUT pad and connect the negative lead of the DMM to the GND pad on the EV kit. 6) Turn on the power supply. 7) Verify that the voltage at VOUT is approximately.v. 8) Connect the load between VOUT and GND. 9) Verify that the voltage at VOUT is approximately.v.

3 Detailed Description of Hardware Evaluating Other Switching Frequencies (FREQ) The switching frequency in fixed-frequency PWM operation is resistor-programmable from 50kHz to.mhz. Set the switching frequency of the IC with a resistor (R FREQ ) from FREQ to GND. R FREQ is calculated as: RFREQ = μs k f s Ω where f S is the desired switching frequency in megahertz. Undervoltage Lockout (UVLO) The UVLO circuitry inhibits switching when V IN or V VDL is below 4.4V (V IN, V VDL rising) or V VL is below.v (V VL rising). Once these voltages are above the thresholds, UVLO clears and the soft-start function activates. A 00mV hysteresis is built in for glitch immunity. Power Good (PWRGD) PWRGD is an open-drain output that goes high impedance once the soft-start ramp has concluded, provided V FB and V REFIN are above 0.54V. PWRGD pulls low when V FB falls below 0.54V for at least 50µs or V REFIN is less than 0.54V. PWRGD is low during shutdown. SYNC and SYNCOUT The MAX8654 features a SYNC function that allows the switching frequency to be synchronized to any external clock frequency that is higher than the internal clock frequency. Drive SYNC with a square wave at the desired synchronization frequency. A rising edge on SYNC triggers the internal SYNC circuitry. Connect SYNC to GND to disable the function and operate with the internal oscillator. The SYNCOUT output generates a clock signal that is 80 out-of-phase with its internal oscillator, or the signal applied to SYNC. This allows for another MAX8654 to be synchronized 80 out-ofphase to reduce the input ripple current. Soft-Start and REFIN The MAX8654 utilizes an adjustable soft-start function to limit inrush current during startup. An 8µA (typ) current source charges an external capacitor (C) connected to SS to increase the capacitor voltage in a controlled manner. The soft-start time is adjusted by the value of the external capacitor from SS to GND. The required capacitance value is determined as: A t C = 8μ ss 06. V where t SS is the required soft-start time in seconds. The MAX8654 also features an external reference input (REFIN). The IC regulates FB to the voltage applied to REFIN. The internal soft-start is not available when using an external reference. A method of soft-start when using an external reference is shown in the MAX8654 data sheet. Connect REFIN to SS to use the internal 0.6V reference (jumper JU). Jumper Settings Jumper JU Function Drive EN high by placing a shunt on JU to turn on the IC. To shut down the IC and reduce quiescent current to 0µA (typ), remove the shunt on JU. During shutdown, the outputs of the MAX8654 are high impedance. Jumper JU Function Place a shunt on jumper JU to connect SYNC to GND. Jumper JU Function Place a shunt on pins - of JU to connect the REFIN pin to the SS pin. When using an external reference, place a shunt on pins - of jumper JU. Evaluating the MAX8688 The MAX8688 is a fully digital power-supply manager that can be tested in conjunction with the MAX8654. Samples of the MAX8688 IC can be ordered from Maxim. To test the MAX8688, populate it with its circuitry, as shown by the schematic or in the component list. Also, place a shunt on pins - of JU. For further information, refer to the MAX8688 IC data sheet.

4 VDL VIN VIN JP JP JP VIN JP JP CC 0μF JU4 CB 0μF R 0Ω C0 0.μF AGND REFIN CA 0μF JP4 JP5 C9 4.7μF C5 0.μF C6 DNI R9 kω PGND PGND PGND VDL IN IN IN IN VP VL C μf C 0.0μF ENABLE JU VIN EN C 0.μF R0 00kΩ R kω VOUT JP EN L μh C5A μf C5B μf C5C μf C4 0.μF JP0 EP 7 6 PGND 5 PGND 4 PGND N.C. GND EN 0 N.C R8.Ω JP9 U MAX C4 0.μF C 470pF R.5kΩ % R5 5Ω C6 6800pF VOUT GND_SIGNAL BST SYNC 0 JU SYNC SYNCOUT 9 JP7 VL ILIM FREQ GND REFIN SS COMP FB PWRGD SYNCOUT R7 75kΩ % R 00kΩ % R6 475Ω C7 0.0μF R 00kΩ VL JP6 PWRGD C8 000pF R4 Ω % FB JU C 0.0μF REFIN Figure a. MAX8654 EV Kit Schematic (Sheet of ) 4

5 TP ISN+ R6 00Ω JP0 4 CLKIN RST TP TP4 OTP C0 00nF C0 00nF OTP DGND DVDD CLKIN RST SDA 4 ISNC ISN+ RS- ISN- U0 MAX8688 RS+ 0 ISN- FLT- 9 R7 00Ω C0 00nF RSC TP REFOUT AVDD AGND DACOUT A A EP C04 μf C0 0.47μF VOUT GND_SIGNAL TP5 C05 00nF A A VOUT VIN VIN+ C07 00nF R0 0Ω R 909Ω D CMPZ460 R4 OPEN R 00kΩ C09 OPEN C08.μF FB REFIN JP0 R5 0kΩ SCL NC8 NC9 ENOUT FLT A SDA A A R05 kω SCL R06 OPEN JP0 WP SCL R08 OPEN SDA VSS 4 VCC SDA R09 OPEN SCL JP04 EN TP6 R04 OPEN R9 00kΩ R0 OPEN R0 kω C06 00nF 5 U0 AT4C0A A A PMBUS ADDRESS: 0x5A R07 kω R0 kω Figure b. MAX8654 EV Kit Schematic (Sheet of ) 5

6 Figure. MAX8654 EV Kit Component Placement Guide Component Side 6

7 Figure. MAX8654 EV Kit PCB Layout Component Side 7

8 Figure 4. MAX8654 EV Kit PCB Layout Inner Layer 8

9 Figure 5. MAX8654 EV Kit PCB Layout Inner Layer 9

10 Figure 6. MAX8654 EV Kit PCB Layout Inner Layer 0

11 Figure 7. MAX8654 EV Kit PCB Layout Inner Layer 4

12 Figure 8. MAX8654 EV Kit PCB Layout Solder Side

13 REVISION NUMBER REVISION DATE DESCRIPTION Revision History PAGES CHANGED 0 5/07 Initial release 0/08 Change in compensation components (C6, C7, C8, R5, and R6),, 4 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, 0 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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