19-2063; Rev 0; 6/01 MAX1778 Evaluation Kit Features ♦ +2.7V to +5.5V Input Range ♦ Output Voltages +8V, >200mA (Step-Up Switching Regulator) +20V, >10mA (Positive Charge-Pump Regulator) -5V, >20mA (Negative Charge-Pump Regulator) +2.5V, >200mA (LDO Linear Regulator) +4V, >150mA Peak (VCOM Buffer) ♦ All Outputs Are Adjustable with Resistors ♦ >91% Efficiency ♦ Internal MOSFET Switches ♦ <1µA (typ) IC Shutdown Current ♦ 1MHz Step-Up Switching Regulator Frequency ♦ 500kHz Charge-Pump Regulator Switching Frequency ♦ Adjustable Fault-Trip Level ♦ Low-Profile External Components ♦ Built-In Transient Load Tester ♦ Surface-Mount Components ♦ Fully Assembled and Tested Ordering Information PART TEMP. RANGE MAX1778EVKIT 0°C to +70°C IC PACKAGE 24 TSSOP Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY C1, C16, C17, C18, C21 5 3.3µF ±10%, 10V X7R ceramic capacitors (1210) Taiyo Yuden LMK325BJ335KD C5, C7, C11, C13, C25−C29 9 1µF ±10%, 16V X7R ceramic capacitors (1206) Murata GRM42-6X7R105K016 C2 1 0.47µF ±10%, 10V X7R ceramic capacitor (0603) Taiyo Yuden LMK107BJ474KA C8 1 1000pF ±10%, 50V X7R ceramic capacitor (0603) Murata GRM39X7R102K050AD C3, C14 2 0.01µF ±10%, 50V X7R ceramic capacitors (0603) Murata GRM39X7R103K050AD C9 1 0.22µF ±10%, 10V X7R ceramic capacitor (0603) Taiyo Yuden LMK107BJ224KA 0 Not installed (0603) 4 0.1µF ±20%, 16V X7R ceramic capacitors (0603) Taiyo Yuden EMK107BJ104MA C12, C20, C24 C4, C6, C10, C22 DESCRIPTION ________________________________________________________________ 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: MAX1778/MAX1880/MAX1881/MAX1882 General Description The MAX1778 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that contains a step-up switching regulator, two charge-pump voltageregulator circuits, a VCOM buffer, and a low-drop out linear regulator (LDO). The step-up switching circuit is configured for a +8V output that provides up to 250mA of current from a +3.0V supply. The EV kit can be powered from a +2.7V to +5.5V supply. The positive charge-pump circuit is configured for a +20V output that provides more than 10mA of current. The negative charge-pump circuit is configured for a -5V output and provides more than 20mA of current. Power for both charge-pump inputs is provided from the step-up switching regulator output. The EV kit also features an LDO linear regulator circuit, which is configured for a +2.5V output that provides more than 200mA of current. Power for the LDO regulator circuit is provided from the input supply. The VCOM buffer provides a +4V output and more than 150mA of peak current. The step-up switching regulator output provides power to the VCOM buffer. The MAX1778 EV kit demonstrates low quiescent current and high efficiency (over 91%). High-frequency operation (500kHz/1MHz) allows the use of tiny surfacemount components and fast transient response. The MAX1778 TSSOP package (1.1mm max) with low-profile external components allows this circuit to be less than 1.2mm in height. A built-in transient load tester facilitates transient load tests. The MAX1778 EV kit can also be used to evaluate the MAX1880, MAX1881, and MAX1882 ICs. MAX1778 Evaluation Kit Evaluates: MAX1778/MAX1880/MAX1881/MAX1882 Component List (continued) DESIGNATION C19 D1 D2, D3, D4 2 QTY 1 1 3 PHONE FAX 470pF ±5%, 50V COH ceramic capacitor (0603) Taiyo Yuden UMK107CH4715Z Central Semiconductor 516-435-1110 516-435-1824 Coilcraft 847-639-6400 847-639-1469 3A, 30V Schottky diode (M-flat) Toshiba CMS02 Fairchild 408-822-2000 408-822-2102 IRC 512-992-7900 512-992-3377 200mA, 25V Schottky diodes (SOT23) Fairchild BAT54S Murata 814-237-1431 814-238-0490 Taiyo Yuden 408-573-4150 408-573-4159 Toshiba 949-455-2000 949-859-3963 D5 1 L1 1 6.8µH inductor Coilcraft LPO25061B-682 1 Q1 1 SUPPLIER DESCRIPTION 200mA, 75V ultra-fast diode (SOT23) Fairchild MMBD4148 N1 Component Suppliers 30V, 11.5A, N-channel MOSFET (SOT223) Fairchild Semiconductor NDT455N 40V, 600mA, NPN transistor (SOT23) Central Semiconductor CMPT2222A R1 1 274kΩ ±1% resistor (0805) R2, R4, R6 3 49.9kΩ ±1% resistors (0805) R3 1 750kΩ ±1% resistor (0805) R5 1 200kΩ ±1% resistor (0805) R7 1 24kΩ ±5% resistor (0805) R8, R10, R12 3 100kΩ ±1% resistors (0805) R9 1 1MΩ ±5% resistor (0805) R11, R13, R16 0 Not installed (0805) R14, R15 2 10kΩ ±1% resistors (0805) R17 1 51Ω ±5% resistor (0805) R18 1 1.0Ω ±1%, 1W resistor (2010) IRC LRC-LR 2010-01-1R00-F R19 1 1.5kΩ ±5% resistor (0805) R20 1 10Ω ±5% resistor (0805) R21 1 10kΩ ±5% resistor (0805) U1 1 MAX1778EUG (24-pin TSSOP) JU1 1 2-pin header None 1 Shunt (JU1) None 1 MAX1778 PC board None 1 MAX1778 data sheet None 1 MAX1778 EV kit data sheet Note: Please indicate that you are using the MAX1778, MAX1880, MAX1881, or MAX1882 when contacting these component suppliers. Quick Start The MAX1778 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. Output Verification 1) Verify that jumper JU1 (SHDN) does not have a shunt across its pins. 2) Connect a voltmeter to the V1 pad. 3) Connect a +2.7V to +5.5V DC power supply to the PIN pad. Connect the supply ground to the GND pad. 4) Turn on the power supply, and verify that the main output (V1) is +8V. 5) Verify that the negative charge-pump regulator output (VN) is -5V. 6) Verify that the positive charge-pump regulator output (VP) is +20V. 7) Verify that the LDO output (LDOOUT) is +2.5V. 8) Verify that the V COM buffer output (BUFOUT) is +4V. For instructions on selecting the feedback resistors for other output voltages, see Evaluating Other Output Voltages. The input voltage range is +2.7V to +5.5V when selecting the output voltage. Detailed Description The MAX1778 evaluation kit step-up switching regulator circuit can be configured for an output voltage up to +13V. A built-in transient load tester (TRANS_LOAD, CSEN) for the step-up switching regulator allows transient load tests up to 1A. _______________________________________________________________________________________ MAX1778 Evaluation Kit The EV kit’s LDO linear regulator circuit is configured for a +2.5V output (LDOOUT) at more than 200mA of current and can be reconfigured for other output voltages by replacing feedback resistors. When using an external transistor (Q1) for the LDO, regulator power for the LDO output is provided by PIN. When an external transistor (Q1) is not used, power is provided by the step-up switching regulator (V1). For even higher output current, the SOT23 NPN transistor (Q1) can be replaced with a larger D-PAK device. The VCOM buffer output (BUFOUT) is a scaled down voltage of the step-up switching regulator (V1) and can be reconfigured for other voltages by replacing the voltage-divider resistors (R10, R11). The step-up switching regulator provides power to the VCOM buffer. A separate analog ground pad (GND) for the VCOM buffer output is provided to reduce noise coupling to the output. The EV kit features an adjustable fault-trip level that can be reconfigured for different fault-trip levels. Unpopulated feedback-compensation PC board pads are provided for the step-up switching regulator. The linear regulator can be configured for different voltages and output currents. The MAX1778 EV kit can also evaluate the MAX1880, MAX1881, and MAX1882. Order the IC from the phone number listed on page 1, and replace the MAX1778 with the appropriate IC. Jumper Selection Shutdown Mode The MAX1778 EV kit features a shutdown mode that reduces the MAX1778 quiescent current. The 2-pin jumper (JU1) selects the MAX1778 shutdown mode. Table 1 lists the selectable jumper options. Output Voltage Selection and Transient Load Test Step-Up SwitchingRegulator Output Voltages The MAX1778 EV kit’s step-up switching-regulator output is set to +8V by feedback resistors (R1, R2). To generate output voltages other than +8V (up to +13V), select different external voltage-divider resistors (R1, R2). The ceramic capacitors (C17, C18, C21) are rated Table 1. Jumper JU1 Functions SHUNT LOCATION SHDN PIN None Connected to PIN through R8 Enabled Connected to GND Shutdown Installed MAX1778 OUTPUT to +10V, so replace them with higher voltage-rated capacitors for output voltages over 10V. Refer to the Output Voltage Selection section in the MAX1778 data sheet for instructions on selecting the resistors. Positive Charge-Pump Output Voltages The MAX1778 EV kit’s positive charge-pump regulator output is set to +20V by feedback resistors (R3, R4). To generate output voltages other than +20V (up to +35V), select different external voltage-divider resistors (R3, R4). Refer to the Output Voltage Selection section in the MAX1778/MAX1880–MAX1885 data sheet for instructions on selecting the resistors. Check that the capacitor voltage rating is adequate for the configuration. Negative Charge-Pump Output Voltages The MAX1778 EV kit’s negative charge-pump regulator output is set to -5V by feedback resistors (R5, R6). To generate output voltages other than -5V (down to -11V), select different external voltage-divider resistors (R5, R6). Refer to the Output Voltage Selection section in the MAX1778/MAX1880–MAX1885 data sheet for instructions on selecting the resistors. LDO Regulator Output Voltages The MAX1778 EV kit’s LDO linear regulator output is set to +2.5V by feedback resistors (R14, R15). To generate output voltages other than +2.5V (+1.25V to V PIN -300mV), select different external voltage-divider resistors (R14, R15). Refer to the Output Voltage Selection section in the MAX1778 data sheet for instructions on selecting the resistors. The power dissipation of the NPN transistor (Q1, 350mW) must not be exceeded. If a larger transistor is required, a “DPAK” surface-mount case may be used to replace Q1 (MJD31, On Semiconductor, or similar recommended). Refer to the External Pass Transistor section in the MAX1778/ MAX1880–MAX1885 data sheet for instructions on selecting a transistor. VCOM Buffer Output Voltages The MAX1778 EV kit’s VCOM buffer output (BUFOUT) is configured to one half of V1’s output voltage (i.e., 0.5 ✕ 8V = +4V) by using the MAX1778 IC’s internal 0.5 volt- _______________________________________________________________________________________ 3 Evaluates: MAX1778/MAX1880/MAX1881/MAX1882 The positive charge-pump circuit can be reconfigured to provide up to +35V by changing feedback resistors, provided that the step-up switching regulator (V1) has been changed to a higher voltage. The negative charge-pump circuit can also be reconfigured to provide up to -11V by changing feedback resistors, provided that the step-up switching regulator (V1) has been adjusted to a higher voltage. Evaluates: MAX1778/MAX1880/MAX1881/MAX1882 MAX1778 Evaluation Kit age divider. Select different external voltage-divider resistors (R10, R11) to generate output voltages other than +4V (+1.2V to +(VSUPB - 1.2V)). Refer to the Output Voltage Selection section in the MAX1778/MAX1880–MAX1885 data sheet for instructions on selecting the resistors. The VCOM buffer has a separate analog ground pad (GND) next to the VCOM buffer output (BUFOUT) to reduce any noise coupling. Transient Load Tester The MAX1778 EV kit features a built-in transient load tester for the step-up switching regulator. Connect a square-wave function generator (50Ω output) to the TRANS_LOAD and GND pads. Set the frequency and duty cycle as required. Note that varying the function generator output voltage (2.0V typ to 10V max) will vary the gate drive and thus will vary the amount of load connected to V1. Set the low and high voltage of the square-wave output according to the desired low- and high-load currents. Load currents can be calculated by measuring the voltage at the CSEN pad (across R18, 1Ω) and GND. Divide the measured voltage by 1Ω to obtain the actual load current. Faults and Maximizing Transient Performance Maximizing Transient Performance The MAX1778 EV kit features several surface-mount, unpopulated PC board pads for installing feedback compensation components (R7, C19, C20). To maximize the transient load performance, remove capacitor C8, connect the INTG pin (pin 2) to the REF pin (pin 9) of IC U1, and remove resistor R7 and capacitor C19. Refer to the Feedback Compensation section in the MAX1778/MAX1880–MAX1885 data sheet for instructions on selecting other resistors and capacitors. Evaluating Other ICs and Different Linear Regulator Configurations Evaluating a MAX1880, MAX1881, or MAX1882 The MAX1778 EV kit can be reconfigured for evaluating the MAX1880, MAX1881, and MAX1882 ICs. U1 (MAX1778) must be removed and replaced with the new IC (24-pin TSSOP package). The linear regulator will not function when evaluating a MAX1880 or MAX1882. Refer to the MAX1778/MAX1880–MAX1885 IC data sheet for information on the various step-up switching frequency and LDO features. Fault-Trip Level The MAX1778 EV kit’s fault-trip level for the step-up switching regulator and the positive charge pump is configured for a +1.1V (0.67 ✕ VREF to 0.87 ✕ VREF) fault-trip level. To reconfigure the EV kit for other fault-trip levels (+0.84V to +1.09V), select different external voltagedivider resistors (R12, R13). Refer to the Fault-Trip Level (FLTSET) section in the MAX1778/MAX1880–MAX1885 data sheet for instructions on selecting the resistors. Linear Regulator Voltages The MAX1778 EV kit can be reconfigured for evaluating other linear regulator voltages and currents. Several components must be replaced to obtain higher voltages or currents. Table 2 lists the components to replace. Table 2. Component List for Evaluating Other Linear Regulators 4 DESIGNATOR CASE 1 CASE 2 CASE 3 CASE 4 LDO Output Voltage (LDOOUT) +7.6V (V1 set to 8V) +9V to +12.4V (V1 set to 13V) +3.3V +2.5V LDO Output Current (LDOOUT) 40mA 40mA 300mA to 500mA 200mA Q1 (external NPN) Not installed Not installed D-PAK (MJD31) SOT23 (2N2222A) C3 Not installed Not installed 0.01µF 0.01µF C14 Not installed Not installed 0.01µF 0.01µF C27 3.3µF 2.2µF 1.0µF 1.0µF C29 Not installed Not installed 1.0µF 1.0µF 10kΩ R14 10kΩ 10kΩ 10kΩ R15 51.1kΩ 60kΩ to 89kΩ 16.5kΩ 10kΩ R16 0Ω 0Ω Not installed Not installed R19 13kΩ 13kΩ 4.02kΩ 3.01kΩ _______________________________________________________________________________________ _______________________________________________________________________________________ R 1 L 2 D3 R5 200kΩ 1% C24 OPEN C1 3.3µF 10V PIN 3 V1 R8 100kΩ 1% R6 49.9kΩ 1% C6 0.1µF BUFOUT R10 100kΩ 1% V1 C2 0.47µF C16 3.3µF 10V REF JU1 C9 0.22µF C26 1.0µF 16V C25 1.0µF R11 OPEN C8 1000pF R20 10Ω 12 9 11 18 7 5 6 4 17 2 23 3 SHDN REF FBN DRVN BUFOUT BUF- SUPB BUF+ SUPN INTG TGND IN MAX1778 U1 L1 6.8µH SUPL LDOOUT GND FBP FLTSET FBL RDY DRVP SUPP PGND FB LX 13 14 8 10 16 15 24 20 19 21 1 22 C28 1.0µF 16V C27 1.0µF 16V R4 49.9kΩ 1% REF FBLDO PIN R2 49.9kΩ 1% R1 274kΩ 1% RDY R13 OPEN R9 1MΩ V1 D1 V1 C4 0.1µF C10 0.1µF R3 750kΩ 1% R12 100kΩ 1% C12 OPEN C19 470pF R7 24kΩ C17 3.3µF 10V 3 3 R19 1.5kΩ C20 OPEN C18 3.3µF 10V D2 D4 2 2 L 1 R L 1 R C21 3.3µF 10V V1 C22 0.1µF C5 1.0µF CSEN N1 4 1 V1 R18 1.0Ω 1% 3 2 FBLDO 1 R14 10kΩ 1% L 2 R 1 C3 0.01µF C11 1.0µF R 2 L R21 10kΩ C14 0.01µF R15 10kΩ 1% R16 OPEN 3 D5 V1 +8V Q1 3 GND VP +20V GND C29 1.0µF 16V C13 1.0µF 16V TRANS_LOAD R17 51Ω GND LDOOUT +2.5V PIN Evaluates: MAX1778/MAX1880/MAX1881/MAX1882 NOTE: REMOVE C8, R7, AND C19, AND SHORT U1-2 (INTG) TO U1-9 (REF) FOR IMPROVED TRANSIENT RESPONSE. C7 1.0µF VN -5V GND GND PIN MAX1778 Evaluation Kit Figure 1. MAX1778 EV Kit Schematic 5 Evaluates: MAX1778/MAX1880/MAX1881/MAX1882 MAX1778 Evaluation Kit 1.0" 1.0" Figure 2. MAX1778 EV Kit Component Placement Guide— Component Side Figure 3. MAX1778 EV Kit PC Board Layout—Component Side 1.0" Figure 4. MAX1778 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. 6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.