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| 19-2076; Rev 0; 7/01 MAX1724 Evaluation Kit General Description 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. o 0.91V to VOUT Input Voltage Range o Two Complete Boost Circuits 3.3V Fixed (MAX1724) 3.6V Adjustable Output (MAX1722) o Up to 50mA Output from a 1-Cell Input Up to 100mA Output from a 2-Cell Input o 1.5A Quiescent Current from VOUT o Up to 90% Efficiency with Synchronous Rectification o Switching Frequency Up to 200kHz o All Surface-Mount Design o Fully Assembled and Tested Board Features Evaluates: MAX1722/MAX1723/MAX1724 Ordering Information PART MAX1724EVKIT TEMP. RANGE 0C to +70C IC PACKAGE THIN SOT23-5 Component List DESIGNATION QTY C1-C4 D1 L1, L2 R1 R2 U1 U2 JU1, JU2 None None None None 4 0 2 1 1 1 1 2 2 1 1 1 DESCRIPTION 10F, 10V X7R ceramic capacitors Taiyo Yuden JMK325BJ106MN Not installed 10H inductors Sumida CDR43-100MC 2M 1% resistor (0805) Venkel CR0805-10W-2004FT 1.02M 1% resistor (0805) Venkel CR0805-10W-1024FT Maxim MAX1724EZK33 (5-pin THIN SOT23, top mark ADQJ) Maxim MAX1722EZK (5-pin THIN SOT23, top mark ADQF) 3-pin headers Shunts JU1, JU2 MAX1724 PC board MAX1722/MAX1723/MAX1724 data sheet MAX1724 EV kit data sheet SUPPLIER Murata Sumida Taiyo Yuden Venkel Component Suppliers PHONE FAX WEB www.murata.com www.sumida.com 814-237-1431 814-238-0490 847-956-0666 847-956-0702 408-573-4150 408-573-4159 www.T-yuden.com 512-794-0081 512-794-0087 www.venkel.com Note: Please indicate that you are using the MAX1724 when contacting these component suppliers. 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. 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. 3) Verify there is a shunt across pins 1 and 2 of jumper JU1 (SHDN), thus enabling the MAX1724. 4) Turn on the power supply and verify that the output is at 3.3V. Note: Quantities are for both circuits. ________________________________________________________________ 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. MAX1724 Evaluation Kit Evaluates: MAX1722/MAX1723/MAX1724 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). 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 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 1-2 2-3 BATT PIN Connected to VBATT Not allowed 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. 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. 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. 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 equivalent) 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. Table 1. MAX1724 Jumper JU1 Functions SHUNT LOCATION 1-2 2-3 SHDN PIN Connected to VBATT Connected to GND MAX1724 OUTPUT MAX1724 enabled, VOUT = 3.3V Shutdown mode, VOUT = VBATT - VDIODE 2 _______________________________________________________________________________________ MAX1724 Evaluation Kit Evaluates: MAX1722/MAX1723/MAX1724 L1 10H U1 MAX1724 VBATT 0.91V TO VOUT GND SHDN 1 C1 10F 10V 1 2 JU1 3 2 3 BATT LX GND OUT SHDN 5 4 C2 10F 10V 3.3V VOUT GND L2 10H VBATT 0.91V TO VOUT C3 10F 10V JU2 1 21 3 2 3 GND OUT FB U2 MAX1722 BATT LX 5 4 R1 2.00M D1 (OPEN) GND VOUT 3.6V C4 10F 10V GND R2 1.02M Figure 1. MAX1724 EV Kit Left-Side Circuit Schematic Figure 2. Right-Side Circuit Schematic for MAX1722 and MAX1723 Evaluation 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 1-2 2-3 SHDN PIN Connected to VBATT Connected to GND MAX1723 OUTPUT MAX1723 enabled, VOUT = 3.6V Shutdown mode, VOUT = VBATT - VDIODE _______________________________________________________________________________________ 3 MAX1724 Evaluation Kit Evaluates: MAX1722/MAX1723/MAX1724 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) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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