MAX1620/MAX1621 19-1214 Rev 1 1/98 Digitally Adjustable LCD Bias Supplies General Description Features The MAX1620/MAX1621 convert a 1.8V to 20V battery 1.8V to 20V Battery Input Voltage voltage to a positive or negative LCD backplane bias Automatic Disable when Display Logic voltage. Backplane bias voltage can be automatically disabled when the display logic voltage is removed, is Shut Down protecting the display. These devices use very little PC Extremely Small QSOP Package board area, come in ultra-small QSOP packages, and 32-Level Internal DAC require only small, low-profile external components. Output voltage can be set to a desired positive or nega- SMBus Serial Interface (MAX1621) tive voltage range with external resistors, and adjusted Positive or Negative Output Voltage over that range with the on-board digital-to-analog con- verter (DAC) or with a potentiometer. The MAX1620/ MAX1621 include a 5-bit DAC, allowing digital software control of the bias voltage. The MAX1620 uses up/down digital signaling to adjust the DAC, and the MAX1621 uses the System Management Bus (SMBus) 2-wire Ordering Information serial interface. PART TEMP. RANGE PIN-PACKAGE These devices use a low-cost, external, N-channel MOSFET power switch or NPN transistor, and can be configured MAX1620EEE -40C to +85C 16 QSOP for positive or negative output voltages. Operating cur- MAX1621EEE -40C to +85C 16 QSOP rent is a low 150A, typically provided from a displays logic supply of 3.0V to 5.5V. The MAX1620/MAX1621 are available in a 16-pin QSOP package. Applications Notebook Computers Typical Operating Circuit Palmtop Computers Personal Digital Assistants Portable Data-Collection Terminals 2V TO 12V Pin Configuration BATT 12.5V TO 23.5V OUT 3V TO V LX DD 5.5V TOP VIEW POL DHI DN (SDA) 1 16 DHI / ON OFF SHDN DLO UP (SCL) 2 15 DLO DOWN DN BATT 3 14 LX PGND UP UP SHDN (SUS) 4 MAX1620 13 PGND MAX1621 MAX1620 POK 5 12 AGND REF DOUT 6 REF 11 V DD FB POL 7 10 DOUT AGND LCDON 8 9 FB POK LCDON QSOP ( ) ARE FOR MAX1621 ONLY. SMBus is a trademark of Intel Corp. Maxim Integrated Products 1 For free samples & the latest literature: Digitally Adjustable LCD Bias Supplies ABSOLUTE MAXIMUM RATINGS V to AGND..............................................................-0.3V to 6V I ....................................................................................-30mA DD DLO PGND to AGND ..................................................................0.3V I ...............................................................................-10mA LCDON BATT, LX, LCDON to AGND....................................-0.3V to 30V Continuous Power Dissipation (T = +70C) A DHI, DLO to PGND.....................................-0.3V to (V + 0.3V) QSOP (derate 8.3mW/C above +70C) ......................667mW DD DOUT, FB, POL, POK, REF to AGND.........-0.3V to (V + 0.3V) Operating Temperature Range DD UP, DN, SHDN to AGND.............................................-0.3V to 6V MAX1620EEE/MAX1621EEE ............................-40C to +85C SCL, SDA, SUS to AGND............................................-0.3V to 6V Storage Temperature Range .............................-65C to +150C I ......................................................................................60mA Lead Temperature (soldering, 10sec) .............................+300C DHI Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (V = 3.3V, V = 10V, T = 0C to +85C, unless otherwise noted.) DD BATT A PARAMETER CONDITIONS MIN TYP MAX UNITS SWITCHING REGULATOR V Operating Range 3.0 5.5 V DD Operating mode, output in regulation, V = 5.5V 150 250 DD V Supply Current A DD Shutdown mode, V = V ,V = 5.5V 920 SHDN DD DD Positive Output Voltage 27 V Negative Output Voltage -27 V Undervoltage Lockout Threshold (Note 1) 1.5 2.8 V BATT = 12V, operating mode 13 20 BATT Input Current A BATT = 12V, shutdown mode 1 LX = 12V, operating mode 13 20 LX Input Current A LX = 12V, shutdown mode 1 BATT Operating Range (Note 2) 1.8 20 V 1.8V BATT 20V, T = +25C 20 A Microsecond-Volt Time Constant (k-factor) s-V 4V BATT 12V, T = 0C to +85C 16.5 23.5 A V = 4.5V 7 DD On-Resistance (DLO, DHI) V = 3.0V 14 DD DHI Output Current (Note 3) V = 5V 50 mA DD DLO Output Current (Note 3) V = 5V -25 mA DD POL = V , 3.0V V 5.5V 1.46 1.5 1.53 V DD DD FB Regulation Voltage POL = AGND, 3.0V V 5.5V -8 0 8 mV DD FB = REF + 100mV -20 10 FB Input Current (Note 3) nA FB = -50mV -10 85 LCDON Low, Sinking Current V = 0.4V, POK = 1.017V -2 -6 mA LCDON LCDON High, Leakage Current V = 28V, POK = 0.967V 1 A LCDON POK Threshold Voltage Voltage on POK rising 0.967 0.992 1.017 V POK Hysteresis 12 mV REFERENCE AND DAC OUTPUT REF Voltage No load 1.47 1.5 1.53 V REF Load Regulation 0A I 25mA 310 mV REF 2 MAX1620/MAX1621