19-2101; Rev 0; 8/01 MAX1845 Evaluation Kit This EV kit is a fully assembled and tested circuit board. It also allows the evaluation of other output voltages in the 1.0V to 5.5V range by changing feedback resistors R1–R4. Ordering Information PART TEMP. RANGE 0oC to +70oC MAX1845EVKIT Features ♦ 7V to 22V Input Voltage Range ♦ 1.8V and 2.5V Output Voltages ♦ 1.0V to 5.5V Adjustable Outputs ♦ 4A Output Current (2.5V Output) ♦ 7A Output Current (1.8V Output) ♦ Adjustable Current-Limit Threshold ♦ 255kHz/345kHz Switching Frequency ♦ Power-Good Output ♦ Over- and Undervoltage Protection ♦ 28-Pin QSOP Package ♦ Low-Profile Components ♦ Fully Assembled and Tested IC PACKAGE 28 QSOP Component List DESIGNATION QTY C1−C5 5 C6−C9 4 C10, C11 2 C12 1 C13 C14, C15, C17, C18 C16 1 DESCRIPTION 10µF, 25V ceramic capacitors (1812) Taiyo Yuden TMK432BJ106KM or TDK C4532X5R1E106M 470µF, 6.3V, 30mΩ low-ESR tantalum capacitors Kemet T510X477M006AS 0.1µF ceramic capacitors (0805) 1µF, 10V X5R ceramic capacitor (0805) Taiyo Yuden LMK212BJ105MG 3.3µF, 10V X5R ceramic capacitor (1206) Taiyo Yuden LMK316BJ335ML 0 Not installed 1 0.22µF ceramic capacitor (1206) 4.7µF, 16V tantalum capacitor Sprague 595D475X0016A2B 100mA, 30V dual Schottky diode Central Semiconductor CMPSH-3A 1A, 30V Schottky diodes Nihon EP10QY03 or Toshiba CRS02 2.2µH power inductor Panasonic ETQP6F2R2SFA or Sumida CDRH127-2R4 C19 1 D1 1 D2, D3 2 L1 1 DESIGNATION QTY DESCRIPTION L2 1 N1 1 N2 1 N3A, N3B 1 R1−R4, R7, R8, R10−R14 0 R5 1 R6 R9, R15 1 2 R19 1 R20 U1 JU1, JU2, JU3 None None None None 1 1 3 3 4 1 1 0.005Ω ±1%, 1W resistor (2512) Dale WSL-2512-R005F or Panasonic ERJM1WSF5MOU 100kΩ ±5% resistor (0805) 1MΩ ±5% resistors (0805) 0.010Ω ±1%, 1/2W resistor (2010) Dale WSL-2010-R010F 10Ω ±5% resistor (0805) MAX1845EEI (28-pin QSOP) 3-pin headers Shunts Rubber feet MAX1845 PC board MAX1845 data sheet None 1 MAX1845EVKIT data sheet 4.7µH power inductor Sumida CDRH124-4R7MC N-channel MOSFET International Rectifier IRF7807 or Fairchild FDS6612A N-channel MOSFET International Rectifier IRF7805 or Fairchild FDS6670A Dual N-channel MOSFET Fairchild FDS6982A Not installed ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX1845 General Description The MAX1845 evaluation kit (EV kit) demonstrates the MAX1845’s standard application circuit. This DC-DC converter steps down high-voltage batteries and/or AC adapters, generating precision, low-voltage rails for use as chipset, DRAM supplies, CPU core, and IO supplies. The MAX1845 EV kit provides dual 1.8V and 2.5V output voltages from a 7V to 22V battery input range. It delivers up to 4A output current for the 2.5V output and 7A for the 1.8V output, with greater than 90% efficiency. The EV kit operates at 255kHz/345kHz switching frequency and has superior line- and load-transient response. Evaluates: MAX1845 MAX1845 Evaluation Kit Component Suppliers SUPPLIER PHONE FAX Central Semiconductor 516-435-1110 516-435-1824 Dale-Vishay 402-564-3131 402-563-6418 Fairchild 408-721-2181 408-721-1635 International Rectifier 310-322-3331 310-322-3332 Kemet 408-986-0424 408-986-1442 Table 1. Jumper JU1 Functions (Output Voltage VOUT1 Control) JU1 1 and 2 2 and 3 Nihon 847-843-7500 847-843-2798 Panasonic 714-373-7939 714-373-7183 Sumida 708-956-0666 708-956-0702 Taiyo Yuden 408-573-4150 408-573-4159 JU2 1 and 2 TDK 847-390-4373 847-390-4428 Toshiba 949-455-2000 949-859-3963 Note: Please indicate that you are using the MAX1845 when contacting these component suppliers. Recommended Equipment • 7V to 22V, power supply, battery, or notebook AC adapter • • DC bias power supply, 5V at 100mA Dummy loads capable of sinking 4A and 7A • • Digital multimeters (DMMs) 100MHz dual-trace oscilloscope ON1 PIN Connected to VCC Connected to GND 2 and 3 ON2 PIN Connected to VCC Connected to GND JU3 1 and 2 2 and 3 OUTPUT VOLTAGE VOUT2 = 2.5V, enabled VOUT2 = 0V, disabled SKIP PIN OPERATING MODE Connected to VCC Low-noise mode, forced fixedfrequency PWM operation. Connected to GND Normal operation, allows automatic PWM/PFM switchover for pulse skipping at light load, resulting in highest efficiency. Table 4. Jumper JU4 Functions (Output Voltage Selection) JU4 4) Verify that the output voltages are 1.8V (VOUT1) and 2.5V (VOUT2). 1 and 2 Evaluating Other Output Voltages 2 and 3 The EV kit outputs are preset to +1.8V and +2.5V. However, the output voltages can also be adjusted between 1.0V and 5.5V by selecting R1/R2 and R3/R4 values. Select feedback resistors R2 (or R4) in the 5kΩ to 50kΩ range. R1 (or R3) is then given by: VOUT1 = 0V, disabled Table 3. Jumper JU3 Functions (SKIP Mode Selection) 2) Verify that the shunts are across JU1 pins 1 and 2, JU2 pins 1 and 2, and JU3 pins 1 and 2. 3) Turn on VIN supply prior to +5V bias power; otherwise, the output UVLO timer will time out and the FAULT latch will be set, disabling the regulator outputs until +5V power is cycled or ON1/ON2 is toggled. VOUT1 = 1.8V, enabled Table 2. Jumper JU2 Functions (Output Voltage VOUT2 Control) Quick Start 1) Ensure that the circuit is connected correctly to the supplies and dummy load prior to applying any power. OUTPUT VOLTAGE Not installed FB1 PIN Connected to VCC Connected to GND (PC board trace) Connected to resistor-divider R3/R4 OUTPUT VOLTAGE VOUT1 = 1.5V VOUT1 = 1.8V Adjustable mode R1 (or R3) = R2 (or R4) x [(VOUT / VFB) - 1] where VFB = 1.0V. 2 _______________________________________________________________________________________ MAX1845 Evaluation Kit JU5 Not installed Not installed Installed Not installed JU6 Not installed Installed Not installed Not installed JU7 Not installed Not installed Not installed Installed TON PIN Floating Connected to VCC Connected to REF Connected to GND VOUT1/VOUT2 FREQUENCY (kHz) 255/345 (as shipped) 170/235 355/485 460/620 IMPORTANT: Don’t change the operating frequency without first recalculating component values because the frequency has a significant effect on the peak current-limit level, MOSFET heating, preferred inductor value, PFM/PWM switchover point, output noise, efficiency, and other critical parameters. Table 6. Jumper JU8 Functions (Overvoltage Protection Selection) JU8 Installed Not installed Not installed OVP PIN Connected to VCC Connected to GND through R9 Connected to voltage between 1.0V and 1.8V through REF divider R9, R10 OVP THRESHOLD OVP is disabled OVP is enabled. OVP threshold is 114% of nominal. ILIM2 PIN SHORT Connected to VCC through a PC board trace OPEN Connected to REF through resistordivider R13/R14. Refer to the CurrentLimit Circuit section in the MAX1845 data sheet for information on selecting R13/R14. JU9 Not installed Installed UVP PIN Connected to VCC through R15 Connected to GND UVP THRESHOLD UVP is enabled. UVP threshold is 70% of nominal. UVP is disabled OVP threshold set to 100% to 180% of nominal VOUT1 and VOUT2 according to divider R9, R10 Table 8. Jumper JU10 Functions (Fixed/Adjustable Current-Limit Selection for VOUT2) JU10 Table 7. Jumper JU9 Functions (Undervoltage Protection Selection) CURRENT-LIMIT THRESHOLD 50mV (default) Adjustable between 30mV and 250mV Table 9. Jumper JU11 Functions (Fixed/Adjustable Current-Limit Selection for VOUT1) JU11 ILIM1 PIN SHORT Connected to VCC through a PC board trace OPEN Connected to REF through resistordivider R11/R12. Refer to the Current-Limit Circuit section in the MAX1845 data sheet for information on selecting R11/R12. CURRENT-LIMIT THRESHOLD 50mV (default) Adjustable between 30mV and 250mV _______________________________________________________________________________________ 3 Evaluates: MAX1845 Table 5. Jumpers JU5/JU6/JU7 Functions (Switching-Frequency Selection) 4 GND VOUT1 1.8V, 7A C6 470µF 6.3V 7V TO 22V VIN C17 OPEN C1 10µF 25V VOUT1 1.5V 1.8V JU4 1, 2 2, 3 R4 OPEN R3 OPEN C7 470µF 6.3V C8 470µF 6.3V C2 10µF 25V ON1 3 D3 2 3 2 8 7 N2 3 8 7 N1 5 6 JU7 540kHz BST1 4 4 ON2 1 1 5 6 JU5 420kHz R7 SHORT (PC TRACE) JU6 200kHz JU4 VCC L1 2.2µH 1 2 VCC REF 2V C3 10µF 25V 3 JU1 VCC 1 2 4 11 5 10 12 2 1 28 24 27 25 ON1 TON REF ON2 FB1 OUT1 CS1 DL1 LX1 BST1 DH1 V+ JU11 26 C16 0.22µF FLOAT = 300kHz 3 JU2 C14 OPEN VCC 1 2 R5 0.005Ω 1% C10 0.1µF R12 OPEN VCC REF ILIM2 ILIM1 MAX1845 13 3 U1 R11 OPEN R13 OPEN UVP OVP GND SKIP PGOOD FB2 OUT2 CS2 DL2 LX2 DH2 BST2 VCC VDD 21 VCC 9 8 23 6 7 14 15 16 20 17 18 19 22 R20 10Ω R14 OPEN JU10 JU9 R15 1MΩ VCC 1 2 R9 1MΩ C12 1µF 10V 2 4 1 7 3 5 BST1 1 2 JU3 3 VCC R10 OPEN PGOOD JU8 VCC R R8 SHORT (PC TRACE) C11 0.1µF L R6 100kΩ C15 OPEN C13 3.3µF VCC D1 3 REF 8 N3-A R19 0.01Ω 1% N3-B 6 C19 4.7µF 16V D2 C5 10µF 25V R2 SHORT (PC TRACE) L2 4.7µH C4 10µF 25V VBIAS +5V R1 OPEN C9 470µF 6.3V VOUT2 2.5V, 4A C18 OPEN VIN Evaluates: MAX1845 MAX1845 Evaluation Kit Figure 1. MAX1845 EV Kit Schematic _______________________________________________________________________________________ MAX1845 Evaluation Kit Figure 3. MAX1845 EV Kit PC Board Layout—Component Side Figure 4. MAX1845 EV Kit PC Board Layout—Internal GND Plane (Layer 2) Figure 5. MAX1845 EV Kit PC Board Layout—Internal GND Plane (Layer 3) _______________________________________________________________________________________ 5 Evaluates: MAX1845 Figure 2. MAX1845 EV Kit Component Placement Guide—Component Side Evaluates: MAX1845 MAX1845 Evaluation Kit Figure 6. MAX1845 EV Kit PC Board Layout—Solder Side Figure 7. MAX1845 EV Kit Component Placement Guide— 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 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.