19-1403; Rev 1; 8/99 MAX1677 Evaluation Kit Features ♦ +0.7V to MAINOUT Battery Input Voltage ♦ Dual Output Voltages +3.3V Main Output and +20V LCD Bias Output +3.3V Main Output and -20V LCD Bias Output ♦ All Outputs Also Adjustable with External Resistors ♦ Up to 350mA from 2-Cell Input (Main Output ) ♦ Up to 140mA from 1-Cell Input (Main Output) ♦ Up to 12mA Output Current (LCD Bias Output) ♦ Internal N-Channel Switches and Synchronous Rectifier ♦ 1µA IC Shutdown Current ♦ 300kHz Switching Frequency ♦ Surface-Mount Components ♦ Fully Assembled and Tested Ordering Information PART TEMP. RANGE MAX1677EVKIT 0°C to +70°C IC PACKAGE 16 QSOP Component List DESIGNATION QTY DESCRIPTION C1, C2, C10, C11 4 100µF, 10V low-ESR tantalum caps AVX TPSD107M010R0100 or Sprague 593D107X0010D2T C3, C5, C13, C14 4 0.1µF ceramic capacitors C4, C12 2 4.7µF, 35V tantalum capacitors AVX TPSC475M035R0600 or Sprague 595D475X0035C2T DESIGNATION QTY DESCRIPTION L1, L3 2 10µH inductors Sumida CR54-100 L2, L4 2 10µH inductors Murata LQH4N100K04 TDK NLC32522T-100K R3 1 1.5MΩ ±5% resistor R4, R12 2 100kΩ ±5% resistors 2 10Ω ±5% resistors 1 2.2µF, 25V ceramic capacitor United Chemi-Con/Marcon THCR30E1E225Z R5, R13 C8 R11 1 1.6MΩ ±5% resistor C16, C17 2 1µF, 16V ceramic capacitors Taiyo Yuden EMK316BJ105KL TDK C3216X7R1C105M R1, R2, R6–R10, R14–R16 0 Not installed C6, C7, C9, C15, D6 0 Not installed U1, U2 2 MAX1677EEE JU1–JU6 6 3-pin headers 2 20V, 0.5A Schottky diodes Motorola MBR0520LT3 None 6 Shunts None 1 MAX1677 PC board None 1 MAX1677 data sheet D1, D3 D2, D4, D5 3 40V, 0.5A Schottky diodes Motorola MBR0540T3 ________________________________________________________________ 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. Evaluates: MAX1677 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. Evaluates: MAX1677 MAX1677 Evaluation Kit Component Suppliers PHONE FAX AVX SUPPLIER 803-946-0690 803-626-3123 Dale-Vishay 402-564-3131 402-563-6418 Motorola 602-303-5454 602-994-6430 Murata 814-237-1431 814-238-0490 Sprague 603-224-1961 603-224-1430 Sumida 708-956-0666 708-956-0702 Taiyo Yuden 408-573-4150 408-573-4159 TDK 847-390-4373 847-390-4428 United ChemiCon/Marcon 847-696-2000 847-696-9278 Note: Please indicate that you are using the MAX1677 when contacting these component suppliers. _________________________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. +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. 2 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. 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. Table 1. Jumper JU1/JU4 Functions SHUNT LOCATION ON PIN VOUT OUTPUT 1&2 Connected to GND Shutdown mode, VOUT = VIN - VDIODE 2&3 Connected to VOUT MAX1677 enabled, VOUT = +3.3V Table 2. Jumper JU2/JU5 Functions SHUNT LOCATION LCDON PIN 1&2 Connected to GND 2&3 Connected to VOUT LCDOUT OUTPUT +LCDOUT = VIN - VDIODE, -LCDOUT = 0V +LCDOUT = +20V, -LCDOUT = -20V _______________________________________________________________________________________ MAX1677 Evaluation Kit Table 3. Jumper JU3/JU6 Functions SHUNT LOCATION CLK/SEL PIN 1&2 Connected to GND Low-power mode, MAX1677 operates in the PFM mode. 2&3 Connected to VOUT High-power, low-noise mode, MAX1677 operates in the PWM mode. CLK/SEL connected to CLK/SEL pad Synchronized PWM highpower mode, CLK/SEL pin is driven by an external clock between 200kHz and 400kHz. Open OPERATING MODE 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. 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 56kΩ 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. _______________________________________________________________________________________ 3 Evaluates: MAX1677 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. 4 CLK/SEL REF 1.25V LCDON ON VIN VIN C5 0.1µF R6 OPEN VOUT VOUT 3 1 3 R17 SHORT 1 JU2 (PC TRACE) 2 JU1 2 9 3 5 8 6 7 11 R7 SHORT (PC TRACE) JU3 VOUT 2 1 3 VOUT GND LBI CLK/SEL REF LCDON LCDPOL ON MAX1677 U1 LCDFB LCDGND LCDLX LBO FB OUT POUT PGND LX 10 13 12 4 2 1 16 14 15 VIN L2 10µH VOUT C3 0.1µF R8 OPEN R5 10Ω D1 MBR0520L L1 10µH C4 4.7µF 35V D2 MBR0540 C2 100µF 10V C1 100µF 10V C6 OPEN C7 OPEN R4 100k R3 1.5M (PC TRACE) R2 SHORT R1 OPEN C16 1µF +LCDOUT +20V LBO VOUT +3.3V Evaluates: MAX1677 MAX1677 Evaluation Kit Figure 1. MAX1677 EV Kit Schematic (Positive LCD) _______________________________________________________________________________________ _______________________________________________________________________________________ CLK/SEL REF 1.25V LCDON ON VIN C14 0.1µF 3 1 3 R18 SHORT 1 JU5 (PC TRACE) 2 JU4 2 9 3 5 8 6 7 11 R16 SHORT (PC TRACE) JU6 VOUT 2 R15 OPEN VOUT 1 3 VOUT GND LBI CLK/SEL REF LCDON LCDPOL ON MAX1677 U2 LCDFB LCDGND LCDLX LBO FB OUT POUT PGND LX 10 13 12 4 2 1 16 14 15 VIN L4 10µH VOUT C13 0.1µF C8 2.2µF VIN R14 OPEN R13 10Ω D3 MBR0520L L3 10µH D4 MBR0540 D5 MBR0540 C15 OPEN D6 OPEN C11 100µF 10V C10 100µF 10V C12 4.7µF 35V C9 OPEN (PC TRACE) R10 SHORT R9 OPEN C17 1µF R12 100k R11 1.6M REF -LCDOUT -20V LBO VOUT +3.3V Evaluates: MAX1677 VIN MAX1677 Evaluation Kit Figure 2. MAX1677 EV Kit Schematic (Negative LCD) 5 Evaluates: MAX1677 MAX1677 Evaluation Kit 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 Evaluates: MAX1677 MAX1677 Evaluation Kit 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 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.