MAX1795/MAX1796/ Low-Supply Current, Step-Up DC-DC Converters MAX1797 with True Shutdown General Description Features The MAX1795/MAX1796/MAX1797 are high-efficiency, > 95% Efficiency step-up DC-DC converters intended for small portable True-Shutdown Circuitry hand-held devices. These devices feature Maxims True Output Disconnects from Input in Shutdown Shutdown circuitry, which fully disconnects the out- No External Schottky Diode Needed put from the input in shutdown, improves efficiency, 25A Quiescent Supply Current and eliminates costly external components. All three devices also feature Maxims proprietary LX-damping Low-Noise Antiringing Feature circuitry for reduced EMI in noise-sensitive applications. LBI/LBO Comparator Enabled in Shutdown For additional in-system flexibility, a battery monitoring 2A Shutdown Current comparator (LBI/LBO) remains active even when the 8-Pin MAX Package DC-DC converter is in shutdown. The input voltage range is +0.7V to V , where V OUT OUT Ordering Information can be set from +2V to +5.5V. Startup is guaranteed from +0.85V. The MAX1795/MAX1796/MAX1797 have a PART TEMP RANGE PIN-PACKAGE preset, pin-selectable 5V or 3.3V output. The output can MAX1795EUA -40C to +85C 8 MAX also be adjusted to other voltages, using two external MAX1796EUA -40C to +85C 8 MAX resistors. The three devices differ only in their current limits, allowing optimization of external components for MAX1797EUA -40C to +85C 8 MAX different loads: The MAX1795, MAX1796, and MAX1797 have current limits of 0.25A, 0.5A, and 1A, respectively. All devices are packaged in a compact, 8-pin MAX package that is only 1.09mm tall and half the size of an 8-pin SO. Applications Portable Digital Audio Players PDAs/Palmtops Wireless Handsets Portable Terminals Pin Configuration Typical Operating Circuit IN 0.7V TO 5.5V TOP VIEW BATT LX LBI 1 8 BATT MAX1795 OUT OUT MAX1795 FB 2 7 OUT MAX1796 LBI MAX1796 FB MAX1797 LBO 3 6 LX MAX1797 LBO SHDN 4 5 GND OFF SHDN MAX ON GND True Shutdown is a trademark of Maxim Integrated Products. 19-1798 Rev 0 12/00MAX1795/MAX1796/ Low-Supply Current, Step-Up DC-DC Converters MAX1797 with True Shutdown Absolute Maximum Ratings OUT, LX, SHDN, LBI, LBO, BATT to GND ..............-0.3V to +6V Operating Temperature Range ........................... -40C to +85C FB ...........................................................-0.3V to (V + 0.3V) Junction Temperature ......................................................+150C OUT I , I .............................................................................1.5A Storage Temperature Range ............................ -65C to +150C LX OUT Output Short-Circuit Duration .................................................. 5s Lead Temperature (soldering, 10s) .................................+300C Continuous Power Dissipation 8-Pin MAX (derate 4.1mW/C above +70C) ............330mW 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 = +2V, OUT = FB (V = +3.3V), SHDN = LBI = GND, T = 0C to +85C, unless otherwise noted. Typical values are at BATT OUT A T = +25C.) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Minimum Input Voltage After startup 0.7 V Operating Voltage V (Note 1) 1.0 5.5 V BATT Startup Voltage T = +25C, R = 3k 0.85 1.0 V A L Startup Voltage Tempco -2.2 mV/C FB = OUT 3.17 3.3 3.43 Output Voltage V V OUT FB = GND 4.80 5.0 5.20 Adjustable Output Voltage Range 2.0 5.5 V MAX1795 100 180 BATT = +2V, FB = OUT MAX1796 200 300 (V = +3.3V) OUT MAX1797 400 550 Steady-State Output Current I mA OUT MAX1795 50 120 BATT = +2V, FB = GND MAX1796 100 200 (V = +5.0V) OUT MAX1797 250 370 Feedback Set-Point Voltage V V = +2V to +5.5V 1.20 1.24 1.28 V FB OUT (Adjustable Mode) Feedback Input Current I V = +1.24V 4 100 nA FB FB NFET 0.17 0.3 Internal NFET, PFET V = +3.3V, OUT R DS(ON) On-Resistance I = 100mA LX PFET 0.27 0.45 MAX1795 0.2 0.25 0.35 LX Switch Current Limit I MAX1796 0.4 0.5 0.625 A LIM (NFET only) MAX1797 0.8 1.0 1.25 LX Leakage Current I V = 0 and +5.5V, V = +5.5V 0.2 A LEAK LX OUT Synchronous Rectifier Turn-Off 25 mA Current Limit Damping Switch On-Resistance R 100 200 400 DAMP Operating Current into OUT V = +1.4V 25 45 A FB (Note 2) Maxim Integrated 2 www.maximintegrated.com