19-2076; Rev 1; 5/05 MAX1724 Evaluation Kit The MAX1724 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that contains two separate boost switching-regulator circuits. The left-side circuit contains a MAX1724 with a preset 3.3V output. Other preset voltages of 2.7V, 3.0V, or 5.0V are also available. The right-side circuit contains a MAX1722, which has an adjustable output voltage. This circuit's output is set for 3.6V. All devices regulate with input voltages from 0.91V to VOUT, making them ideal for 1- or 2-cell alkaline and NiMH battery applications. The right-side circuit may also be used to evaluate the MAX1723, which features a shutdown (SHDN) mode. The MAX1722/MAX1724 has a BATT pin, which lowers the guaranteed startup voltage from 1.2V to 0.91V. The MAX1722/MAX1723/MAX1724 feature synchronous rectification and ultra-low (1.5A typ) quiescent current for maximum efficiency and long battery life. Operation up to 200kHz allows tiny surface-mount components. Component List Features 0.91V to VOUT Input Voltage Range Two Complete Boost Circuits 3.3V Fixed (MAX1724) 3.6V Adjustable Output (MAX1722) Up to 50mA Output from a 1-Cell Input Up to 100mA Output from a 2-Cell Input 1.5A Quiescent Current from VOUT Up to 90% Efficiency with Synchronous Rectification Switching Frequency Up to 200kHz All Surface-Mount Design Fully Assembled and Tested Board Ordering Information PART TEMP RANGE IC PACKAGE MAX1724EVKIT 0C to +70C THIN SOT23-5 Quick Start The MAX1724 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. DESIGNATION QTY DESCRIPTION C1-C4 4 10F, 16V X7R ceramic capacitors TDK C3225X7R1C106MT or Murata GRM32DR71C106MA D1 0 Not installed L1, L2 2 10H inductors Sumida CDR43-100MC R1 1 2M 1% resistor (0805) Venkel CR0805-10W-2004FT 3) Verify there is a shunt across pins 1 and 2 of jumper JU1 (SHDN), thus enabling the MAX1724. R2 1 1.02M 1% resistor (0805) Venkel CR0805-10W-1024FT 4) Turn on the power supply and verify that the output is at 3.3V. U1 1 Maxim MAX1724EZK33 (5-pin THIN SOT23, top mark ADQJ) U2 1 Maxim MAX1722EZK (5-pin THIN SOT23, top mark ADQF) 3.6V Output (right side): 1) Connect a 0.91V to 3.6V supply to the VBATT pad. Connect the supply ground to the GND pad. JU1, JU2 2 3-pin headers None 2 Shunts JU1, JU2 None 1 MAX1724 PC board Note: Quantities are for both circuits. 3.3V Output (left side): 1) Connect a 0.91V to 3.3V supply to the VBATT pad. Connect the supply ground to the GND pad. 2) Connect a voltmeter to the VOUT pad. 2) Connect a voltmeter to the VOUT pad. 3) Verify there is a shunt across pins 1 and 2 of jumper JU2 to connect BATT to VBATT for the MAX1722. 4) Turn on the power supply and verify that the output is at 3.6V. For instructions on selecting feedback resistors for other output voltages, see Evaluating Other Output Voltages (Right Side). ________________________________________________________________ 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: MAX1722/MAX1723/MAX1724 General Description Evaluates: MAX1722/MAX1723/MAX1724 MAX1724 Evaluation Kit Component Suppliers SUPPLIER PHONE FAX WEBSITE Murata 814-237-1431 814-238-0490 www.murata.com Sumida 847-956-0666 847-956-0702 www.sumida.com TDK 847-803-6100 847-390-4405 www.component.tdk.com Venkel 512-794-0081 512-794-0087 www.venkel.com Note: Please indicate that you are using the MAX1724 when contacting component suppliers. Detailed Description The MAX1724 EV kit contains two separate boost switching-regulator circuits. The left-side circuit (MAX1724) supplies a preset 3.3V output. The rightside circuit (MAX1722) supplies an adjustable 3.6V output, but can also be set from 2.0V to 5.5V. Both circuits regulate with input voltages from 0.91V to VOUT, but can accept higher input voltages (below 5.5V) if it is acceptable for the output voltage to rise above the set VOUT. Output current for both circuits is 50mA with a 1.2V input, and 100mA for a 2.4V input. The 3.6V output voltage (right side) can also be adjusted from 2.0V to 5.5V using external resistors R1 and R2. The input voltage ranges from 0.91V to (V OUT ) when operating from a DC source. The MAX1724 boost converter (left side) features a 0.1A shutdown mode. Jumper Selection MAX1724 Circuit (Left Side) The MAX1724 EV kit's shutdown mode reduces the IC's quiescent current to 0.1A (typ), preserving battery life. Jumper JU1 selects the shutdown mode for the MAX1724. Table 1 lists the MAX1724 jumper options. Table 1. MAX1724 Jumper JU1 Functions SHUNT LOCATION SHDN PIN MAX1724 OUTPUT 1-2 Connected to VBATT MAX1724 enabled, VOUT = 3.3V 2-3 Connected to GND Shutdown mode, VOUT = VBATT - VDIODE MAX1722 Circuit (Right Side) When jumper JU2 on the right-side circuit is used with a MAX1722, pins 1 and 2 must be connected together so 2 that BATT is connected to the battery input (VBATT). When the right-side circuit is used to evaluate a MAX1723, see Evaluating the MAX1723 section. Table 2 lists the MAX1722 jumper options. Table 2. MAX1722 Jumper JU2 Functions SHUNT LOCATION BATT PIN 1-2 Connected to VBATT 2-3 Not allowed 3.6V Output (right side): 1) Connect a 0.91V to 3.6V supply to the VBATT pad. Connect the supply ground to the GND pad. 2) Connect a voltmeter to the VOUT pad. 3) Verify there is a shunt across pins 1 and 2 of jumper JU2 to connect BATT to VBATT for the MAX1722. 4) Turn on the power supply and verify that the output is at 3.6V. For instructions on selecting feedback resistors for other output voltages, see Evaluating Other Output Voltages (Right Side). Evaluating Other Output Voltages (Right Side) The MAX1722 output is set to 3.6V by feedback resistors R1 and R2. To generate output voltages other than 3.6V (2.0V to 5.5V), select different external voltagedivider resistors (R1, R2). Refer to the Setting the Output Voltage section in the MAX1722/MAX1723/ MAX1724 data sheet for instructions on selecting R1 and R2 for the MAX1722/MAX1723. Evaluating the MAX1723 The MAX1723 can be evaluated using the MAX1722 circuit (right side). Replace the MAX1722 with a MAX1723EZK. Diode D1 (Motorola MBR0520L or equiv- _______________________________________________________________________________________ MAX1724 Evaluation Kit L2 10H VBATT U1 0.91V TO VOUT MAX1724 1 VBATT 0.91V TO VOUT C1 10F 16V GND SHDN 1 2 JU1 3 BATT LX 2 GND SHDN 5 JU2 U2 1 2 1 MAX1722 BATT LX 3 2 OUT 3 GND C3 10F 16V 4 C2 10F 16V 3.3V VOUT GND OUT 3 GND FB D1 (OPEN) 5 VOUT 3.6V 4 R1 2.00M C4 10F 16V R2 1.02M GND Figure 1. MAX1724 EV Kit Left-Side Circuit Schematic Figure 2. Right-Side Circuit Schematic for MAX1722 and MAX1723 Evaluation alent) may be necessary for low-voltage startup. Refer to the Low-Voltage Startup Oscillator section in the MAX1722/MAX1723/MAX1724 data sheet for additional instructions on selecting D1. The MAX1723 circuit features a shutdown mode that reduces current to 0.1A (typ), preserving battery life. Jumper JU2 selects the MAX1723 shutdown mode. Table 3 lists the MAX1723 jumper options. Table 3. MAX1723 Jumper JU2 Functions SHUNT LOCATION SHDN PIN MAX1723 OUTPUT 1-2 Connected to VBATT MAX1723 enabled, VOUT = 3.6V 2-3 Connected to GND Shutdown mode, VOUT = VBATT - VDIODE _______________________________________________________________________________________ 3 Evaluates: MAX1722/MAX1723/MAX1724 L1 10H Evaluates: MAX1722/MAX1723/MAX1724 MAX1724 Evaluation Kit Figure 3. MAX1724 EV Kit Component Placement Guide-- Component Side Figure 4. MAX1724 EV Kit PC Board Layout--Component Side Figure 5. MAX1724 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. 4 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.