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| 19-2702; Rev 0; 12/02 MAX8504 Evaluation Kit General Description The MAX8504 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that demonstrates the MAX8504 1MHz pulse-width modulated (PWM) step-down DC-to-DC converter optimized for powering the power amplifier (PA) in wireless applications. The EV kit provides a 1.25V output from a 2.6V to 5.5V input range and can deliver 600mA of load current. The output voltage can be reconfigured to voltages in the range of 1.25V to 2.5V by adding two resistors. The MAX8504 EV kit can also be used to evaluate the MAX8500 and the MAX8503 converters that can dynamically control the output voltage from 0.4V to VIN. o Integrated 0.25 Bypass PFET o Externally Fixed 1.25V Output Voltage o 600mA Output Current o Adjustable Output Voltages (1.25V to 2.5V) o 2.6V to 5.5V Input Voltage Range o Low 0.1A (typ) Quiescent Current in Shutdown Mode o Evaluates MAX8500/MAX8503 Converters (Adjustable Output 0.4V to VIN) o Surface-Mount Construction o Fully Assembled and Tested Features Evaluates: MAX8500/MAX8503/MAX8504 Component List DESIGNATION C1 QTY 1 DESCRIPTION 10F 20%, 6.3V X5R ceramic capacitor (0805) TDK C2012X5R0J106MT 0.1F 10%, 25V X7R ceramic capacitor (0603) TDK C1608X7R1E104KT 0.22F 10%, 10V X5R ceramic capacitor (0603) Taiyo Yuden LMK107BJ224KA 4.7F 20%, 6.3V X5R ceramic capacitor (0805) TDK C2012X5R0J475MT or Taiyo Yuden JMK212BJ475MG 560pF 5%, 50V C0G ceramic capacitor (0603) TDK C1608COG1H561JT or Taiyo Yuden UMK107CG561JZ Not installed, capacitor (0603) Not installed, scope-probe connector 3-pin headers 4.7H, 900mA inductor Sumida CDRH3D16-4R7NC Not installed, resistors (0603) 9.1k 5% resistor (0603) MAX8504ETC 12-pin thin QFN 4mm x 4mm, topmark: AABS Shunts (JU1, JU2, JU3) MAX8504 PC board Ordering Information PART MAX8504EVKIT TEMP RANGE 0C to 70C IC PACKAGE 12 Thin QFN C2 1 Component Suppliers SUPPLIER Sumida Taiyo Yuden TDK PHONE FAX WEBSITE 847-545-6700 847-545-6720 www.sumida.com 800-348-2496 847-925-0899 www.t-yuden.com 847-803-6100 847-390-4405 www.component. tdk.com C3 1 C4 1 C5 1 Note: Please indicate that you are using the MAX8504 when contacting these component suppliers. Quick Start The MAX8504 EV kit is a fully assembled and tested surface-mount board. Follow the steps below for board operation. Do not turn on the power supply until all connections are completed. 1) Verify that a shunt is connected across pins 1 and 2 of jumper JU1 (output enabled). 2) Verify that a shunt is connected across pins 1 and 2 of jumper JU2 (PWM mode enabled). 3) Verify that a shunt is connected across pins 2 and 3 of jumper JU3 (high-power bypass mode disabled). 4) Connect a voltmeter across the VOUT and the GND pads to monitor the output voltage. 1 C6 J1 JU1, JU2, JU3 L1 R1, R2 R3 U1 None None 0 0 3 1 0 1 1 3 1 ________________________________________________________________ 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. MAX8504 Evaluation Kit Evaluates: MAX8500/MAX8503/MAX8504 5) Connect a 2.6V to 5.5V power supply to the VIN pad. Connect the power-supply ground terminal to the GND pad. 6) Turn on the power supply and verify that the output voltage is 1.25V. SKIP/PWM Mode Installing a shunt across pins 2 and 3 of jumper JU2 enables skip-mode operation. This allows automatic PWM control at medium and heavy current loads and skip mode at light current loads to improve efficiency and reduce quiescent current. Installing a shunt across pins 1 and 2 of JU2 enables forced-PWM operation. Forced-PWM operation is desirable in sensitive RF and data-acquisition applications to ensure that switching harmonics do not interfere with sensitive IF and data sampling frequencies. Forced-PWM operation uses higher supply current with no load compared to skip mode. See Table 2 for JU2 configuration. Detailed Description The MAX8504 EV kit circuit board demonstrates the MAX8504 1MHz PWM step-down DC-to-DC converter circuit that is optimized to power a PA in wireless applications. The EV kit requires a power supply with a 2.6V to 5.5V output range. The EV kit is configured for an output voltage of 1.25V and can provide 600mA of load current. The output voltage can be reconfigured by installing feedback resistors R1 and R2 on the board. The EV kit board features jumpers that enable the user to configure the shutdown, SKIP/PWM, and high-power (HP) bypass modes. The MAX8504 EV kit board can also be used to evaluate the MAX8500/MAX8503 converters that can dynamically control the output voltage in the range of 0.4V to VIN from an analog control signal supplied by the user. Table 2. Jumper JU2 (SKIP/PWM) SHUNT LOCATION 1 and 2 2 and 3 SKIP PIN Connected to VIN Connected to GND EV KIT OPERATION PWM operation at all loads SKIP mode at light loads and PWM mode at medium and heavy loads Output Voltage The MAX8504 EV kit circuit is configured to regulate the output voltage to 1.25V. The output voltage (VOUT) can be adjusted in the range of 1.25V to 2.5V by cutting open the short across R1 and installing feedback resistors, R1 and R2. Select feedback resistor R2 between 5k and 50k, and R1 is determined by the following equation: R1 = R2 (VOUT / VFB - 1) where VFB = 1.25V and VOUT is the desired output voltage. High-Power Bypass Mode Jumper JU3 allows the user to enable or disable the high-power bypass mode of the MAX8504 converter. When the high-power mode is enabled, the converter stops regulating the output voltage and the output voltage VOUT is equal to the input voltage VIN. When the high-power mode is disabled, the converter regulates the output voltage to the programmed voltage. See Table 3 for JU3 configuration. Removing the shunt on jumper JU3 and applying a CMOS logic-level signal to the HP pad on the EV kit board can also control the high-power bypass mode. Shutdown Mode The EV kit contains jumper JU1 to allow the user to switch the MAX8504 converter from enable to shutdown mode. Shutdown mode reduces the supply current to 0.1A (typ) and sets the output voltage to 0V. See Table 1 for JU1 configurations. Table 3. Jumper JU3 (High-Power Mode) SHUNT LOCATION 1 and 2 2 and 3 HP PIN Connected to VIN Connected to GND Connected to HP pad EV KIT OPERATION High-power bypass mode enabled, VOUT = VIN High-power bypass mode disabled, VOUT = 1.25V Output controlled by the user (user-supplied control signal must be connected to HP pad). Table 1. Jumper JU1 (Shutdown) SHUNT LOCATION 1 and 2 2 and 3 SHDN PIN Connected to VIN EV KIT OPERATION Output enabled, VOUT = 1.25V Connected to GND Shutdown, VOUT = 0V None 2 _______________________________________________________________________________________ MAX8504 Evaluation Kit Evaluating MAX8500/MAX8503 The MAX8504 EV kit circuit board comes with the MAX8504 converter installed. The MAX8504 EV kit board can also be used to evaluate the MAX8500/ MAX8503 converters, which do not require feedback resistors to set the output voltage. An analog control signal connected to the REFIN pad dynamically adjusts the output voltage from 0.4V to VIN. The gain from REFIN to VOUT is internally set to 1.76 (MAX8500) or 2 (MAX8503). See Table 4 for details on the various features of the MAX8500/MAX8503/MAX8504 converters. Follow these steps to evaluate the MAX8500/MAX8503 converters on the MAX8504 EV kit board: 1) Replace the MAX8504 converter (U1) with the alternate converter (Table 4). 2) Cut open the short across R1. 3) Install a 0.01F (0603 case) capacitor on R2. 4) Connect a DC voltage signal to the REFIN pad to set the output voltage VOUT (VOUT = gain x REFIN). 5) Install a shunt across pins 1 and 2 of JU3. 6) Refer to the Compensation, Stability, and Output Capacitor section of the MAX8500-MAX8504 data sheet to verify component values for the application. Evaluates: MAX8500/MAX8503/MAX8504 Table 4. Alternate Converters PART MAX8500ETC MAX8503ETC MAX8504ETC* *Installed. GAIN 1.76x 2x N/A IC TOP MARK AABQ AABU AABS J1 VIN GND C1 10F C2 0.1F 8 9 BATTP BATT OUT 10 L1 4.7H LX 2 VOUT C3 0.22F R1 SHORT (PC TRACE) 3 R2 OPEN SKIP VIN 1 2 3 JU3 5 HP FB REF 7 VOUT U1 MAX8504 SHDN VIN 1 12 2 3 VIN 1 2 3 C4 4.7F GND JU1 REFIN GND 11 JU2 HP 4 GND 1 PGND 6 COMP R3 9.1k C5 560pF C6 OPEN Figure 1. MAX8504 EV Kit Schematic _______________________________________________________________________________________ 3 MAX8504 Evaluation Kit Evaluates: MAX8500/MAX8503/MAX8504 Figure 2. MAX8504 EV Kit Component Placement Guide-- Component Side Figure 3. MAX8504 EV Kit PC Board Layout--Component Side Figure 4. MAX8504 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) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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