MAX856MAX859 19-0211 Rev 4 5/96 3.3V/5V or Adjustable-Output, Step-Up DC-DC Converters General Description Features 0.8V to 6.0V Input Supply Voltage The MAX856MAX859 are high-efficiency, CMOS, step- up, DC-DC switching regulators for small, low input volt- 0.8V Typ Start-Up Supply Voltage age or battery-powered systems. The MAX856/MAX858 85% Efficiency at 100mA accept a positive input voltage between 0.8V and V OUT 25A Quiescent Current and convert it to a higher, pin-selectable output voltage of 1A Shutdown Mode 3.3V or 5V. The MAX857/MAX859 adjustable versions accept 0.8V to 6.0V input voltages and generate higher 125mA and 500mA Switch-Current Limits Permit Use of Low-Cost Inductors adjustable output voltages in the 2.7V to 6.0V range. Typical efficiencies are greater than 85%. Typical quies- Up to 500kHz Switching Frequency cent supply current is 25A (1A in shutdown). 1.5% Reference Tolerance Over Temperature The MAX856MAX859 combine ultra-low quiescent supply Low-Battery Detector (LBI/LBO) current and high efficiency to give maximum battery life. An 8-Pin SO and MAX Packages internal MOSFET power transistor permits high switching frequencies. This benefit, combined with internally set peak inductor current limits, permits the use of small, low-cost Ordering Information inductors. The MAX856/MAX857 have a 500mA peak PART TEMP. RANGE PIN-PACKAGE inductor current limit. The MAX858/MAX859 have a 125mA MAX856CSA 0C to +70C 8 SO peak inductor current limit. MAX856CUA 0C to +70C 8 MAX Applications MAX856C/D 0C to +70C Dice* 3.3V to 5V Step-Up Conversion MAX856ESA -40C to +85C 8 SO Palmtop Computers MAX856MJA -55C to +125C 8 CERDIP Portable Data-Collection Equipment MAX857CSA 0C to +70C 8 SO Personal Data Communicators/Computers MAX857CUA 0C to +70C 8 MAX Medical Instrumentation MAX857C/D 0C to +70C Dice* 2-Cell & 3-Cell Battery-Operated Equipment MAX857ESA -40C to +85C 8 SO Glucose Meters MAX857MJA -55C to +125C 8 CERDIP Ordering Information continued at end of data sheet. * Dice are tested at T = +25C only. A Typical Operating Circuit Contact factory for availability. INPUT Pin Configuration 0.8V TO V OUT TOP VIEW OUTPUT 1 SHDN 8 5V AT 100mA LX 47H OR 2 7 3/5 GND 3.3V AT 125mA MAX856 3 6 OUT REF ON/OFF SHDN LX MAX858 1N5817 4 5 LBI LBO 68F MAX856 SO/MAX 3V/5V SELECT 3/5 OUT LOW-BATTERY 1 SHDN 8 LBI LX DETECTOR 2 7 INPUT FB GND LOW-BATTERY MAX857 REF LBO 3 6 OUT REF GND DETECTOR OUTPUT MAX859 4 5 LBI LBO SO/MAX Maxim Integrated Products 1 For free samples & the latest literature: 3.3V/5V or Adjustable-Output, Step-Up DC-DC Converters ABSOLUTE MAXIMUM RATINGS Supply Voltage (OUT to GND) ...................................-0.3V, +7V Reverse Battery Current (T +45C, Note 1) .................750mA A Switch Voltage (LX to GND) .......................................-0.3V, +7V Operating Temperature Ranges SHDN, LBO to GND ....................................................-0.3V, +7V MAX85 C ......................................................0C to +70C LBI, REF, 3/5, FB to GND .........................-0.3V, (V + 0.3V) MAX85 E ....................................................-40C to +85C OUT Reference Current (I ) ..................................................2.5mA MAX85 MJA .................................................-55C to +125C REF Continuous Power Dissipation (T = +70C) Junction Temperature .....................................................+150C A SO (derate 5.88mW/C above +70C) .........................471mW Storage Temperature Range ............................-65C to +160C MAX (derate 4.1mW/C above +70C) ......................330mW Lead Temperature (soldering, 10sec) ............................+300C CERDIP (derate 8.00mW/C above +70C) .................640mW Note 1: Reverse battery current is measured from the Typical Operating Circuits battery input terminal to GND when the battery is connected backwards. A reverse current of 750mA will not exceed the SO or CERDIP package dissipation limits but, if left for an extended time (more than ten minutes), may degrade performance. 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 (Circuits of Figure 2, V = 2.5V, I = 0mA, T = T to T , unless otherwise noted. Typical values are at T = +25C.) IN LOAD A MIN MAX A PARAMETER CONDITIONS MIN TYP MAX UNITS MAX856, 3/5 = 0V, 0mA I 100mA 4.80 5.0 5.20 LOAD MAX856, 3/5 = 3V, 0mA I 150mA 3.17 3.3 3.43 LOAD MAX857, V = 5V, 0mA I 100mA 4.80 5.0 5.20 OUT LOAD Output Voltage 2V V 3V V IN MAX858, 3/5 = 0V, 0mA I 25mA 4.80 5.0 5.20 LOAD MAX858, 3/5 = 3V, 0mA I 35mA 3.17 3.3 3.43 LOAD MAX859, V = 5V, 0mA I 25mA OUT LOAD 4.80 5.0 5.20 Minimum Start-Up I = 0mA 0.8 1.8 V LOAD Supply Voltage Minimum Operating Voltage 0.8 V Quiescent Supply Current in I = 0mA, 3/5 = 3V, LBI = 1.5V, V = 3.47V, LOAD OUT 25 60 A 3.3V Mode (Note 2) (FB = 1.5V, MAX857/MAX859 only) No Load Battery Current Output set for 3.3V, measured at V in Figure 2, R3 omitted. 60 A IN MAX85 C 1 Shutdown Quiescent Current SHDN = 0V, 3/5 = 3V, LBI = 1.5V, V = 3.47V, OUT A (Note 2) (FB = 1.5V, MAX857/MAX859 only) MAX85 E/M 15 MAX856/MAX857 500 Peak Inductor Current Limit mA MAX858/MAX859 125 Reference Voltage No REF load 1.23 1.25 1.27 V Reference-Voltage Regulation 3/5 = 3V, -20A REF load 250A, C = 0.22F 0.8 2.0 % REF LBI Input Threshold With falling edge 1.22 1.25 1.28 V LBI Input Hysteresis 25 mV LBO Output Voltage Low I = 2mA 0.4 V SINK LBO Output Leakage Current LBO = 5V 1 A 2 MAX856MAX859