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| 19-1403; Rev 1; 8/99 MAX1677 Evaluation Kit General Description The MAX1677 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that contains two separate switching-regulator circuits. The first circuit is configured for a +3.3V main output and +20V LCD bias voltage. It accepts inputs from +0.7V to +3.3V. The main +3.3V output supplies up to 350mA from a 2-cell input, or 140mA from a 1-cell input, while the LCD bias output supplies up to 12mA at +20V. The second circuit converts a +0.7V to +3.3V battery voltage to a +3.3V main output and a -20V LCD bias voltage. The main +3.3V output supplies up to 350mA from a 2-cell input, or 140mA from a 1-cell input, while the LCD bias output supplies 10mA at -20V. The MAX1677 features internal N-channel MOSFET switches, a synchronous rectifier, low-battery comparator, and selectable PFM/PWM mode. The MAX1677 EV kit provides low quiescent current and high efficiency-- up to 95% for maximum battery life. Operation at 300kHz allows the use of tiny surface-mount inductors. Features o +0.7V to MAINOUT Battery Input Voltage o Dual Output Voltages +3.3V Main Output and +20V LCD Bias Output +3.3V Main Output and -20V LCD Bias Output o All Outputs Also Adjustable with External Resistors o Up to 350mA from 2-Cell Input (Main Output ) o Up to 140mA from 1-Cell Input (Main Output) o Up to 12mA Output Current (LCD Bias Output) o Internal N-Channel Switches and Synchronous Rectifier o 1A IC Shutdown Current o 300kHz Switching Frequency o Surface-Mount Components o Fully Assembled and Tested Evaluates: MAX1677 Ordering Information PART MAX1677EVKIT TEMP. RANGE 0C to +70C IC PACKAGE 16 QSOP Component List DESIGNATION QTY C1, C2, C10, C11 C3, C5, C13, C14 C4, C12 4 DESCRIPTION 100F, 10V low-ESR tantalum caps AVX TPSD107M010R0100 or Sprague 593D107X0010D2T 0.1F ceramic capacitors 4.7F, 35V tantalum capacitors AVX TPSC475M035R0600 or Sprague 595D475X0035C2T 2.2F, 25V ceramic capacitor United Chemi-Con/Marcon THCR30E1E225Z 1F, 16V ceramic capacitors Taiyo Yuden EMK316BJ105KL TDK C3216X7R1C105M Not installed 20V, 0.5A Schottky diodes Motorola MBR0520LT3 40V, 0.5A Schottky diodes Motorola MBR0540T3 DESIGNATION QTY L1, L3 2 DESCRIPTION 10H inductors Sumida CR54-100 10H inductors Murata LQH4N100K04 TDK NLC32522T-100K 1.5M 5% resistor 100k 5% resistors 10 5% resistors 1.6M 5% resistor Not installed MAX1677EEE 3-pin headers Shunts MAX1677 PC board MAX1677 data sheet 4 L2, L4 R3 R4, R12 R5, R13 R11 R1, R2, R6-R10, R14-R16 U1, U2 JU1-JU6 2 1 2 2 1 0 2 6 6 1 1 2 C8 1 C16, C17 C6, C7, C9, C15, D6 D1, D3 D2, D4, D5 2 0 2 3 None None None ________________________________________________________________ Maxim Integrated Products 1 For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. MAX1677 Evaluation Kit Evaluates: MAX1677 Component Suppliers SUPPLIER AVX Dale-Vishay Motorola Murata Sprague Sumida Taiyo Yuden TDK United ChemiCon/Marcon PHONE 803-946-0690 402-564-3131 602-303-5454 814-237-1431 603-224-1961 708-956-0666 408-573-4150 847-390-4373 847-696-2000 FAX 803-626-3123 402-563-6418 602-994-6430 814-238-0490 603-224-1430 708-956-0702 408-573-4159 847-390-4428 847-696-9278 Detailed Description The MAX1677 EV kit contains two separate switchingregulator circuits. The first circuit provides a +3.3V main output and +20V LCD bias output. The second circuit provides a +3.3V main output and -20V LCD bias output. Both circuits require a +0.7V to +3.3V input voltage range. The main +3.3V output supplies up to 350mA from a 2-cell input, or 140mA from a 1-cell input, while the LCD bias output supplies up to 12mA. The main output voltage can also be adjusted from +2.5V to +5.5V with external resistors. The LCD output is also adjustable. The main boost converter has three operational modes: a low-power PFM mode, a highpower PWM mode, and a high-power PWM mode with the internal oscillator synchronized to an external clock. Note: Please indicate that you are using the MAX1677 when contacting these component suppliers. Jumper Selection Shutdown Mode The MAX1677 EV kit features a shutdown mode that reduces the MAX1677 quiescent current to less than 1mA (typ), preserving battery life. The 3-pin headers, JU1 and JU4, select the shutdown mode for each circuit. Table 1 lists the selectable jumper options. Controlling the LCD Using LCDON Pin LCDON is used to turn on the LCD bias voltage. Jumpers JU2 and JU5 control the LCDON pins for the +LCD and -LCD output circuits, respectively. The 3.3V outputs must also be on for the LCD outputs to operate. Table 2 lists the LCDON jumper options. _________________________Quick Start The MAX1677 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 and +LCD Output 1) Connect a +1.1V to +3.3V supply to the VIN pad. Connect the ground to the GND pad. Note: The input voltage may drop as low as 0.7V after startup. 2) Connect voltmeters to the VOUT and +LCDOUT pads. 3) Verify that the shunts are across pins 2 and 3 on JU1, JU2, and JU3. 4) Turn on the power supply and verify that the main output is at +3.3V and the LCD bias output is at +20V. Table 1. Jumper JU1/JU4 Functions SHUNT LOCATION 1&2 2&3 ON PIN Connected to GND Connected to VOUT VOUT OUTPUT Shutdown mode, VOUT = VIN - VDIODE MAX1677 enabled, VOUT = +3.3V +3.3V and -LCD Output 1) Connect a +1.1V to +3.3V supply to the VIN pad. Connect the ground to the GND pad. Note: The input voltage may drop as low as 0.7V after start-up. 2) Connect voltmeters to the VOUT and -LCDOUT pads. 3) Verify that the shunts are across pins 2 and 3 on JU4, JU5, and JU6. 4) Turn on the power supply and verify that the main output is at +3.3V and the -LCD Bias output is at -20V. For instructions on selecting the feedback resistors for other output voltages, refer to the Design Procedure section in the MAX1677 data sheet. Table 2. Jumper JU2/JU5 Functions SHUNT LOCATION 1&2 2&3 LCDON PIN Connected to GND Connected to VOUT LCDOUT OUTPUT +LCDOUT = VIN - VDIODE, -LCDOUT = 0V +LCDOUT = +20V, -LCDOUT = -20V 2 _______________________________________________________________________________________ MAX1677 Evaluation Kit Operating Mode The main boost converter has three operational modes: a low-power PFM mode; a high-power, low-noise PWM mode; and a high-power PWM mode with the internal oscillator synchronized to an external clock. The EV kit operates at 300kHz switching frequency and allows the use of small inductor values. The switching frequency can also be synchronized to an external clock ranging from 200kHz to 400kHz. The 3-pin headers JU3 and JU6 select the operating mode for each circuit. Table 3 lists the jumper options. Evaluating Other Output Voltages The main output is set to +3.3V by grounding the feedback pins (FB) via PC traces shorting R2 and R10. To generate main output voltages other than +3.3V (+2.5V to +5.5V), cut the traces across R2 and R10 and select the external voltage divider resistors (R1, R2 or R9, and R10). Refer to Design Procedure section in the MAX1677 data sheet for instructions on selecting R1, R2 and R9, and R10. The 20V LCD bias output voltages are set with voltage dividers (R3, R4 or R11, and R12) at the LCD feedback pins (LCDFB). To generate LCD output voltages other than 20V, refer to Setting the LCD Output Voltage section in the MAX1677 data sheet. Evaluates: MAX1677 Table 3. Jumper JU3/JU6 Functions SHUNT LOCATION 1&2 CLK/SEL PIN OPERATING MODE Low-power mode, MAX1677 operates in the PFM mode. High-power, low-noise mode, MAX1677 operates in the PWM mode. Synchronized PWM highpower mode, CLK/SEL pin is driven by an external clock between 200kHz and 400kHz. Changing the LCD Current Limit The LCD inductor current limit can be set to 225mA or 350mA. The EV kit is factory-configured for 350mA. To set the limit to 225mA, cut the PC trace shorting R17 or R18 and insert a 56k resistor. This allows the use of the smallest possible inductors for low-current displays. See the LCD Boost Converter section of the MAX1677 data sheet for more information. Connected to GND 2&3 Connected to VOUT Open CLK/SEL connected to CLK/SEL pad _______________________________________________________________________________________ 3 Evaluates: MAX1677 MAX1677 Evaluation Kit Figure 1. MAX1677 EV Kit Schematic (Positive LCD) VOUT L1 10H 11 ON D1 MBR0520L 7 LCDPOL PGND 16 R5 10 C3 0.1F C7 OPEN 2 VOUT R8 OPEN 5 CLK/SEL LBO VIN L2 10H D2 MBR0540 4 R1 OPEN R2 SHORT (PC TRACE) 14 C2 100F 10V C16 1F LX 15 VOUT +3.3V 3 JU1 2 R17 SHORT VOUT (PC TRACE) VOUT 3 POUT JU2 6 LCDON OUT 1 1 2 C1 100F 10V 1 4 U1 8 REF VIN ON LCDON REF 1.25V C5 0.1F VOUT 3 JU3 2 1 VIN R6 OPEN 3 LBI LCDLX 12 FB MAX1677 CLK/SEL LBO +LCDOUT +20V C4 4.7F 35V C6 OPEN R3 1.5M R7 SHORT (PC TRACE) LCDGND 13 9 GND _______________________________________________________________________________________ LCDFB 10 R4 100k VIN VOUT L3 10H 11 ON D3 MBR0520L 7 LCDPOL PGND 16 R13 10 C13 0.1F C15 OPEN 2 VOUT R14 OPEN 5 CLK/SEL LBO VIN L4 10H 4 VIN D6 OPEN R9 OPEN R10 SHORT (PC TRACE) 14 C11 100F 10V C17 1F LX 15 VOUT +3.3V 3 JU4 2 R18 SHORT (PC TRACE) VOUT 3 POUT JU5 6 LCDON OUT 1 1 2 C10 100F 10V ON 1 Figure 2. MAX1677 EV Kit Schematic (Negative LCD) U2 8 REF LCDON REF 1.25V C14 0.1F VOUT 3 JU6 2 1 R15 OPEN 3 LBI LCDLX R16 SHORT (PC TRACE) LCDGND 12 C8 2.2F 13 FB MAX1677 CLK/SEL LBO VIN D5 MBR0540 D4 MBR0540 C12 4.7F 35V -LCDOUT -20V C9 OPEN R11 1.6M R12 100k 9 GND Evaluates: MAX1677 _______________________________________________________________________________________ LCDFB 10 REF MAX1677 Evaluation Kit 5 MAX1677 Evaluation Kit Evaluates: MAX1677 1.0" Figure 3. MAX1677 EV Kit Component Placement Guide--Component Side 6 _______________________________________________________________________________________ MAX1677 Evaluation Kit Evaluates: MAX1677 1.0" Figure 4. MAX1677 EV Kit PC Board Layout--Component Side _______________________________________________________________________________________ 7 MAX1677 Evaluation Kit Evaluates: MAX1677 1.0" Figure 5. MAX1677 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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