 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| 19-2080; Rev 0; 07/01 MAX1844 Evaluation Kit General Description The MAX1844 evaluation kit (EV kit) demonstrates the MAX1844's standard 4A application circuit. This DC-DC converter steps down high-voltage batteries and/or AC adapters, generating a precision, low-voltage rail for use as chipset, DRAM, and other low-voltage supplies. The MAX1844 EV kit provides a 1.8V output voltage from a 7V to 24V battery input range. It delivers up to 4A output current with greater than 90% efficiency. The EV kit operates at 300kHz switching frequency and has superior line- and load-transient response. 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 and R2. o 7V to 24V Input Voltage Range o Accurate Current Sense o Preset 1.8V/2.5V Output Voltage o 1.0V to 5.5V Adjustable Output o 4A Output Current o 300kHz Switching Frequency o Power-Good Output o Over/Undervoltage Protection o 20-Pin QSOP Package o Low-Profile Components o Fully Assembled and Tested Features Evaluates: MAX1844 Ordering Information PART MAX1844EVKIT TEMP. RANGE 0oC to +70oC IC PACKAGE 20 QSOP Component List DESIGNATION QTY C1 1 DESCRIPTION 10F, 25V ceramic capacitor (1812) Taiyo Yuden TMK432BJ106KM or TDK C4532X5R1E106M 330F, 6.3V 40m low-ESR capacitor Sanyo 6TPB330M 0.1F ceramic capacitor (0805) 0.22F ceramic capacitor (1206) 4.7F, 10V X5R ceramic capacitor (1206) Taiyo Yuden LMK316BJ475ML 3.3F, 10V X5R ceramic capacitor (1206) Taiyo Yuden LMK316BJ335ML 2200pF ceramic capacitor (0805) 1A Schottky diode Nihon EP10QY03, International Rectifier 10MQ040N, or Nihon EC10QS03 100mA, 30V Schottky diode Central Semiconductor CMPSH-3 U1 JU1, JU2 JU9, JU10 None None None None 1 2 2 4 1 1 1 DESIGNATION QTY L1 N1A, N1B C2 C3 C4 C5 1 1 1 1 R1, R2, R11, R13, R14, R15 R3 R4 R5, R6 R7 R8 R9 R10 1 1 0 1 1 2 1 1 1 1 DESCRIPTION 4.7H power inductor Sumida CDRH124-4R7MC Dual N-channel MOSFET Fairchild FDS6982A Not installed (0805) 130k 1% resistor (0805) 100k 5% resistor (0805) 1M 5% resistors (0805) 20 5% resistor (0805) 200 5% resistor (0805) 274k 1% resistor (0805) 0.015 1% 1/2W resistor (2010) IRC LR2010-01-R015-F or Dale WSL-2010-R015F MAX1844EEP (20-pin QSOP) 2-pin headers 3-pin headers Shunts (JU1, JU2, JU9, JU10) MAX1844 PC board MAX1844 data sheet MAX1844 EV kit data sheet C6 C7 1 1 D1 1 D2 1 ________________________________________________________________ Maxim Integrated Products 1 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. MAX1844 Evaluation Kit Evaluates: MAX1844 Component Suppliers SUPPLIER Central Semiconductor Dale Fairchild IR IRC Nihon Sanyo Sumida Taiyo Yuden TDK PHONE 516-435-1110 402-564-3131 408-721-2181 310-322-3331 361-992-7900 847-843-7500 619-661-6835 708-956-0666 408-573-4150 847-390-4373 FAX 516-435-1824 402-563-6296 408-721-1635 310-252-7175 361-992-3377 847-843-2798 619-661-1055 708-956-0702 408-573-4159 847-390-4428 The output voltage can also be adjusted between 1.0V and 5.5V by selecting R1 and R2 values. Cut the PC board trace shorting JU7, then select feedback resistor R2 in the 5k to 50k range. R1 is then given by: R1 = R2 ((VOUT / VFB) - 1) where VFB = 1.0V. See MAX1844 data sheet for optimizing components for output voltage selection. Jumper Settings Table 1. Jumper JU1 Functions (Shutdown Mode) SHUNT LOCATION ON OFF SHDN/PIN Connected to VCC Connected to GND MAX1844 OUTPUT MAX1844 enabled Shutdown mode, VOUT = 0 Note: Please indicate that you are using the MAX1844 when contacting these component suppliers. Equipment Needed * 7V to 24V power supply, battery, or notebook AC adapter * DC bias power supply, 5V at 100mA * Dummy load capable of sinking 4A * Digital multimeter (DMM) * 100MHz dual-trace oscilloscope ON Connected to VCC Table 2. Jumper JU2 Functions (Low-Noise Mode) SHUNT LOCATION SKIP/PIN OPERATIONAL MODE Low-noise mode, forced fixed-frequency PWM operation. Normal operation, allows automatic PWM/PFM switchover for pulse skipping at light load, resulting in highest efficiency. Quick Start 1) Ensure that the circuit is connected correctly to the supplies and dummy load prior to applying any power. 2) Verify that the shunts are across JU1, JU2, JU9 pins 1 and 2, and JU10 pins 2 and 3. 3) Turn on battery power prior to +5V bias power; otherwise, the output UVLO timer will time out and the FAULT latch will be set, disabling the regulator until +5V power is cycled or shutdown is toggled. 4) Observe the 1.8V output with the DMM and/or oscilloscope. Look at the LX switching-node and MOSFET gate-drive signals while varying the load current. OFF Connected to GND Table 3. Jumper JU3 Functions (Fixed/Adjustable Current-Limit Selection) SHUNT LOCATION ON ILIM PIN Connected to VCC, (remove R3/R9 divider) Connected to REF through voltage-divider R3/R9. Refer to the Current-Limit Circuit section in the MAX1844 data sheet for information on selecting R3/R9. CURRENT-LIMIT THRESHOLD 100mV Detailed Description Evaluating Other Output Voltages The EV kit output is preset to +1.8V. If a 2.5V output is desired, cut the trace shorting JU7 and install a short across R2. OFF Adjustable from 25mV to 200mV. Programmed for 65mV by R3 and R9. 2 _______________________________________________________________________________________ MAX1844 Evaluation Kit Evaluates: MAX1844 Table 4. Jumpers JU4, JU5, and JU6 Functions (Switching-Frequency Selection) JU4 Not Installed Installed Not Installed Not Installed JU5 Not Installed Not Installed Installed Not Installed JU6 Not Installed Not Installed Not Installed Installed TON PIN Floating Connected to VCC Connected to REF Connected to GND FREQUENCY (kHz) 300 (as shipped) 200 450 600 Important: Don't change the operating frequency without first recalculating component values. Frequency has a significant effect on preferred inductor value, peak current-limit level, MOSFET heating, PFM/PWM switchover point, output noise, efficiency, and other critical parameters. Table 5. Jumper JU7 Functions (Output Voltage Selection) JU7 Installed Not Installed Installed FB PIN Connected to VCC Connected to GND through R2 (R1 = open) Short on R2 OUTPUT VOLTAGE VOUT = 1.8V (default) VOUT = 2.5V Table 7. Jumper JU9 Functions (Undervoltage Protection Selection) JU9 1 and 2 2 and 3 UVP PIN Connected to VCC Connected to GND Connected to resistor-divider R14/R15 UVP THRESHOLD UVP is enabled. UVP threshold is 70% of nominal. UVP is disabled. Refer to the MAX1844 data sheet for information on setting UVP in adjustable mode. Adjustable from 1V to 5.5V Refer to the MAX1844 data sheet for information on setting VOUT in adjustable mode. Not Installed Not Installed Connected to resistor-divider R1/R2 Table 6. Jumper JU8 Functions (Latching/Nonlatching Overvoltage Protection) JU8 1 and 2 2 and 3 LATCH PIN Connected to VCC Connected to GND OVP BEHAVIOR Nonlatching Latching (default) Table 8. Jumper JU10 Functions (Overvoltage Protection Selection) JU10 1 and 2 2 and 3 OVP PIN Connected to VCC Connected to GND OVP THRESHOLD OVP is disabled. OVP is enabled. OVP threshold is 114.5% of nominal. Refer to the MAX1844 data sheet for information on setting OVP in adjustable mode. Not Installed Connected to resistor-divider R13/R11 _______________________________________________________________________________________ 3 MAX1844 Evaluation Kit Evaluates: MAX1844 VBIAS +5V C5 4.7F 10V VCC R7 20 C6 3.3F 10V D2 CMPSH-3 VBATT 7V TO 24V 13 16 VCC V+ VDD 14 VCC BST 18 20 19 C3 0.1F 7 4 5 6 N1-B C1 10F 25V L1 4.7H D1 VOUT 1.8V SHDN JU1 R5 1M 3 VCC DH SHDN LX U1 ILIM DL MAX1844 3 REF R9 274k 1% JU3 7 R3 130k 1% VCC JU2 17 R6 1M 8 JU5 450KHz C4 0.22F FLOAT = 300kHz 15 JU6 600KHz 2 LATCH VCC SKIP 8 N1-A 12 1 2 C2 330F 6.3V R1 OPEN 1 SKIP CS REF 2V OUT REF 6 C7 2200pF 5 R10 0.015 1% R8 200 GND VCC JU7 VCC R4 100k PGOOD R2 OPEN VCC JU4 VCC 200KHz 1 2 3 JU8 FB TON PGOOD 10 VCC 9 UVP 4 R13 OPEN REF JU10 1 2 3 R11 OPEN R15 OPEN 1 2 JU9 3 OVP R14 OPEN REF GND 11 Figure 1. MAX1844 EV Kit Schematic 4 _______________________________________________________________________________________ MAX1844 Evaluation Kit Evaluates: MAX1844 1.0" 1.0" Figure 2. MAX1844 EV Kit Component Placement Guide-- Component Side Figure 3. MAX1844 EV Kit PC Board Layout--Component Side 1.0" Figure 4. MAX1844 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ______________________5 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
Price & Availability of MAX1844EVKIT
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |