19-4778; Rev 0a; 8/98 MAX668 Evaluation Kit Features ♦ +3V to VOUT Input Range (as shipped) ♦ +12V or Adjustable Output Voltage ♦ Output Current Up to 1A ♦ N-Channel External MOSFET ♦ 4µA IC Shutdown Current ♦ 500kHz Switching Frequency ♦ Surface-Mount Components ♦ Fully Assembled and Tested Component List DESIGNATION QTY C1 1 68µF, 20V, low-ESR tantalum cap Sprague 593D686X0020E2W or AVX TPSE686M020R0150 C5 1 120µF, 20V, low-ESR tantalum cap Sprague 594D127X0020R2T C2 1 0.1µF ceramic capacitor Ordering Information PART MAX668EVKIT TEMP. RANGE 0°C to +70°C IC PACKAGE 10 µMAX Note: To evaluate the MAX669, request a MAX669EUB free sample with the MAX668EVKIT. EV Kit Application Circuit Capabilities VIN(MIN) (V) VOUT (V) IOUT (A) 1.8 12 0.4 1.8 24 0.1 2.5 12 0.65 3 5 3 3 12 1 3 36 0.02 12 24 0.5 Note: Design information for these applications is included. The shaded row shows EV kit configuration as shipped. DESCRIPTION C3 1 0.22µF ceramic capacitor C4, C8 2 1µF ceramic capacitors C7 1 220pF ceramic capacitor C6 0 Not installed D1 1 3A Schottky diode Hitachi HRF302A or Motorola MBRS340T3 L1 1 4.7µH power inductor Sumida CDRH104-4R7 (shielded), Coiltronics UP2B-4R7, or Coilcraft DO3316P-472 N1 1 N-channel MOSFET Fairchild FDS6680 or International Rectifier IRF7801 R1 1 0.020Ω, 1%, 1/2W resistor Dale WSL-2010-R020F or IRC LR2010-01-R020F R2 1 218kΩ, 1% resistor R3 1 24.9kΩ, 1% resistor R4 1 100kΩ, 1% resistor U1 1 MAX668EUB JU1, JU2 2 3-pin headers JU3 1 2-pin header None 2 Shunts (JU1, JU2) None 1 MAX668/MAX669 PC board None 1 MAX668/MAX669 data sheet ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468. Evaluates: MAX668/MAX669 General Description The MAX668 evaluation kit (EV kit) combines a constant-frequency, pulse-width-modulation (PWM) stepup controller with an external N-channel MOSFET and Schottky diode to provide a regulated output voltage. The EV kit accepts a +3V to VOUT input and converts it to a +12V output for currents up to 1A, with greater than 90% conversion efficiency. The EV kit operates at 500kHz, allowing the use of small external components. The MAX668 EV kit is a fully assembled and tested surface-mount circuit board. This EV kit can also be configured for the application circuits listed in the EV Kit Application Circuit Capabilities table. For input voltages below 3V and down to 1.8V, replace the MAX668 with a MAX669. The MAX669 must always operate in bootstrapped mode (JU2 shunt across pins 1 and 2). Evaluates: MAX668/MAX669 MAX668 Evaluation Kit Component Suppliers PHONE FAX AVX SUPPLIER 803-946-0690 803-626-3123 CoilCraft 708-639-6400 708-639-1469 Coiltronics 561-241-7876 561-241-9339 Dale-Vishay 402-564-3131 402-563-6418 Fairchild 408-721-2181 408-721-1635 Hitachi 888-777-0384 650-244-7947 International Rectifier 310-322-3331 310-322-3332 IRC 512-992-7900 512-992-3377 Motorola 602-303-5454 602-994-6430 Siliconix 408-988-8000 408-970-3950 Sprague 603-224-1961 603-224-1430 Sumida 708-956-0666 708-956-0702 Vishay/Vitramon 203-268-6261 203-452-5670 Note: Please indicate that you are using the MAX668 when contacting these component suppliers. If the minimum input voltage is below +3.0V, use the MAX669 with VCC bootstrapped from VOUT (Table 1). In bootstrapped mode, if VOUT is always less than +5.5V, then LDO may be shorted to V CC to eliminate the dropout voltage of the LDO regulator. This increases the gate drive to the MOSFET, which lowers the MOSFET on-resistance but increases the MAX668 supply current due to gate-charge loss. If VIN is greater than +3.0V, the MAX668’s VCC can be powered from VIN. This will decrease quiescent power dissipation, especially when V OUT is large. If V IN is always less than +5.5V, LDO may be shorted to VCC to eliminate the dropout voltage of the LDO regulator. If VIN is in the range of +3V to +4.5V, then the user may still want to bootstrap from VOUT to increase gate drive to the MOSFET at the expense of power dissipation. If VIN is always greater than +4.5V, the VCC input should always be tied to VIN, since bootstrapping from VOUT will not increase the gate drive from LDO, but quiescent power dissipation will rise. Jumpers JU2 and JU3 control the VCC and LDO inputs (see MAX668/MAX669 data sheet). Jumper Selection _________________________Quick Start The MAX668 EV kit is fully assembled and tested. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed. 1) Place the shunt on JU1 across pins 1 and 2. Verify that the shunt is across JU2 pins 2 and 3 (VCC is tied to VIN) and JU3 is open (LDO is open). 2) Connect a +5V supply to the V IN pad. Connect ground to the GND pad. 3) Connect a voltmeter to the VOUT pad. 4) Turn on the power supply and verify that the output voltage is 12V. _______________Detailed Description The MAX668 EV kit provides a regulated +12V output voltage from an input source as low as +3V. It drives loads up to 1A with greater than 90% conversion efficiency. This EV kit is shipped configured in the nonbootstrapped mode (VCC is tied to VIN). However, there are several methods of connecting V CC and LDO depending on the specific design including input and output voltage range, quiescent power dissipation, MOSFET selection, and load. 2 The 3-pin header JU1 selects shutdown mode. Table 1 lists the selectable jumper options. The 3-pin header JU2 selects bootstrapped mode. Table 2 lists the selectable jumper options. For VCC less than 5.5V, use the 2-pin header JU3 to short LDO to VCC. This eliminates the internal linear regulator (LDO) dropout voltage. For the MAX668, this allows operation with input voltages down to 2.7V. Table 3 lists the selectable jumper options. Other Output Voltages The MAX668 EV kit can also be used to evaluate other output voltages. Refer to the Output Voltage Selection section in the MAX668 data sheet for instructions on selecting the feedback resistors R2 and R3. For output voltages greater than 15V, replace C5 (20V) with a capacitor that has a higher voltage rating. In addition to the standard EV kit configuration of 3VIN to 12V OUT at 1A, the EV Kit Application Circuit Capabilities table listed several common Input/Output combinations. Table 4 lists the components recommended for these alternative circuits. _______________________________________________________________________________________ MAX668 Evaluation Kit SHUNT LOCATION SYNC/SHDN PIN MAX668 OUTPUT 1 and 2 Connected to VCC MAX668 enabled, VOUT = 12V. MAX668 operates at internal frequency. 2 and 3 Connected to GND Shutdown mode, VOUT = VIN - diode Floating MAX668 can be externally synchronized when the SYNC/SHDN pad is clocked. Not installed Table 2. Jumper JU2 Functions SHUNT LOCATION VCC PIN MAX668 MODE 1 and 2 Connected to VOUT Bootstrapped mode 2 and 3 Connected to VIN Non-bootstrapped mode Table 3. Jumper JU3 Functions SHUNT LOCATION LDO PIN On Connected to VCC Off Open _______________________________________________________________________________________ 3 Evaluates: MAX668/MAX669 Table 1. Jumper JU1 Functions Evaluates: MAX668/MAX669 MAX668 Evaluation Kit Table 4. Components for Alternate Application Circuits VIN (MIN) (V) 1.8 1.8 2.5 3 VOUT IOUT (V) (A) 12 24 12 5 3 36 12 24 MAXIM PART NO. JU2 BOOTSTRAPPED vs. NON-BOOTSTRAPPED L1 (µH) R1 (mΩ) R2 R3 R4 (kΩ) (kΩ) (kΩ) 0.4 4.7 1&2 Sumida MAX669 Bootstrapped CDRH10 4-4R7 20 Dale WSL- 218 24.9 100 2010R020F 0.1 1.0 1&2 Coilcraft MAX669 Bootstrapped D03316102 D1 N1 C1 C6 Hitachi HRF302A 68µF 120µF International 20V 20V AVX Sprague Rectifier IRF7401 TPSE686M 594D127X 020R0150 0020R2T 15 Dale WSL- 454 24.9 200 2010R015F Hitachi HRF302A 68µF 22µF 22µF 20V 35V 35V International AVX AVX AVX Rectifier TPSE686M TPSE226M TPSE226M IRF7401 020R0150 035R0300 035R0300 0.65 4.7 Sumida 1&2 MAX669 Bootstrapped CDRH10 4-4R7 20 Dale WSL- 218 24.9 100 2010R020F Hitachi HRF302A 68µF 120µF International 20V 20V Rectifier AVX Sprague IRF7401 TPSE686M 594D127X 020R0150 0020R2T 3 4.7 Sumida 1&2 MAX668 Bootstrapped CDRH12 7-4R7 15 Dale WSL2512R015F 24.9 100 Hitachi HRF502A Fairchild FDS6680 330µF 10V Kemet T510X337 M010 2&3 NonBootstrapped 4.7 Sumida CD434R7 100 Dale WSL- 398 24.9 100 1206R100F Central Semiconductor CMPD914 Fairchild FDS5610 10µF 2.2µF 6.3V, X7R 50V, X7R Taiyo Kemet Yuden C1825C22 JMK325BJ1 5MR0RAC 06MN Open 2&3 MAX668 NonBootstrapped 22 Sumida CD73220 50 Dale Motorola WSL- 453 24.9 100 MBRS140T3 2010R050F Fairchild FDS6680 33µF 22µF 20V 35V AVX AVX TPSD336M TPSE226M 020R0200 035R0300 Open 0.020 MAX668 0.5 75 Note: This table lists components recommended for building other application circuits using the MAX668 EV kit. 4 C5 _______________________________________________________________________________________ Open Open 330µF 330µF 10V 10V Kemet Kemet T510X337 T510X337 M010 M010 REF 1.25V SYNC/ SHDN VCC 2 1 JU1 C1 68µF 20V 3 VOUT JU2 1 3 2 C2 0.1µF R4 100k 1% C3 0.22µF JU3 VCC 2 4 10 9 1 C4 1µF FREQ REF SYNC/ SHDN VCC LDO MAX668 U1 GND FB PGND CS+ EXT 3 5 7 6 8 R1 0.02Ω N1 D1 MBRS340T3 L1 4.7µH C7 220pF C5 120µF 20V C6 OPEN R3 24.9k 1% R2 218k 1% C8 1µF VOUT 12V, 1A Evaluates: MAX668/MAX669 VIN MAX668 Evaluation Kit Figure 1. MAX668 EV Kit Schematic _______________________________________________________________________________________ 5 Evaluates: MAX668/MAX669 MAX668 Evaluation Kit 1.0" Figure 2. MAX668 EV Kit Component Placement Guide— Component Side 1.0" 1.0" Figure 3. MAX668 EV Kit PC Board Layout—Component Side Figure 4. MAX668 EV Kit PC Board Layout—Solder Side 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. 6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.