MAX1556/MAX1556A/MAX1557 19-3336 Rev 3 1/11 16A I , 1.2A PWM Q Step-Down DC-DC Converters General Description Features The MAX1556/MAX1556A/MAX1557 are low-operating- Up to 97% Efficiency current (16A), fixed-frequency step-down regulators. 95% Efficiency at 1mA Load Current High efficiency, low-quiescent operating current, low Low 16A Quiescent Current dropout, and minimal (27A) quiescent current in dropout make these converters ideal for powering 1MHz PWM Switching portable devices from 1-cell Li-ion or 3-cell alkaline/NiMH Tiny 3.3H Inductor batteries. The MAX1556 delivers up to 1.2A has pin- Selectable 3.3V, 2.5V, 1.8V, 1.5V, 1.3V, 1.2V, 1.0V, selectable 1.8V, 2.5V, and 3.3V outputs and is also and Adjustable Output adjustable. The MAX1557 delivers up to 600mA has pin- selectable 1V, 1.3V, and 1.5V outputs and is also 1.2A Guaranteed Output Current adjustable. (MAX1556/MAX1556A) The MAX1556/MAX1556A/MAX1557 contain a low-on- Voltage Positioning Optimizes Load-Transient resistance internal MOSFET switch and synchronous Response rectifier to maximize efficiency and dropout perfor- Low 27A Quiescent Current in Dropout mance while minimizing external component count. A Low 0.1A Shutdown Current proprietary topology offers the benefits of a high fixed- frequency operation while still providing excellent effi- No External Schottky Diode Required ciency at both light and full loads. A 1MHz PWM Analog Soft-Start with Zero Overshoot Current switching frequency keeps components small. Both Small, 10-Pin, 3mm x 3mm TDFN Package devices also feature an adjustable soft-start to minimize battery transient loading. Ordering Information The MAX1556/MAX1556A/MAX1557 are available in a tiny 10-pin TDFN (3mm x 3mm) package. TOP PART TEMP RANGE PIN-PACKAGE Applications MARK MAX1556ETB+ -40C to +85C 10 TDFN-EP* ACQ PDAs and Palmtop Computers MAX1556ETB/V+T -40C to +85C 10 TDFN-EP* AWS Cell Phones and Smart Phones MAX1556AETB+ -40C to +85C 10 TDFN-EP* AUJ Digital Cameras and Camcorders MAX1557ETB+ -40C to +85C 10 TDFN-EP* ACR Portable MP3 and DVD Players *EP = Exposed paddle. Hand-Held Instruments +Denotes a lead(Pb)-free/RoHS-compliant package. /V denotes an automotive qualified part. T = Tape and reel. Pin Configuration Typical Operating Circuit OUTPUT TOP VIEW INPUT 0.75V TO V IN 2.6V TO 5.5V INP LX MAX1556 1 IN 10 D1 MAX1556A GND 2 9 INP MAX1557 IN PGND MAX1556 SS 3 8 LX D1 MAX1556A VOLTAGE OUT 4 7 PGND SELECT OUT D2 MAX1557 SHDN 5 6 D2 ON SS OFF SHDN GND TDFN Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLE16A I , 1.2A PWM DC-DC Q Step-Down Converters ABSOLUTE MAXIMUM RATINGS IN, INP, OUT, D2, SHDN to GND ..........................-0.3V to +6.0V Operating Temperature Range ...........................-40C to +85C Junction Temperature......................................................+150C SS, D1 to GND.............................................-0.3V to (V + 0.3V) IN PGND to GND .......................................................-0.3V to +0.3V Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C LX Current (Note 1)...........................................................2.25A Soldering Temperature (reflow) .......................................+260C Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (T = +70C) A 10-Pin TDFN (derate 24.4mW/C above +70C) .......1951mW Note 1: LX has internal clamp diodes to GND and IN. Applications that forward bias these diodes should take care not to exceed the ICs package power-dissipation limits. 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 = V = V = 3.6V, T = -40C to +85C. Typical values are at T = +25C, unless otherwise noted.) (Note 2) IN INP SHDN A A PARAMETER CONDITIONS MIN TYP MAX UNITS Input Voltage 2.6 5.5 V Undervoltage-Lockout Threshold V rising and falling, 35mV hysteresis (typ) 2.20 2.35 2.55 V IN No switching, D1 = D2 = GND 16 25 Quiescent Supply Current A Dropout 27 42 T = +25C 0.1 1 A Shutdown Supply Current SHDN = GND A T = +85C 0.1 A Output Voltage Range 0.75 V V IN No load -0.25 +0.75 +1.75 300mA load -0.75 0 +0.75 T = 0C to +85C A 600mA load -1.5 -0.75 0 (Note 3) 1200mA load, MAX1556 -2.75 -2.25 -1.25 Output Accuracy 1200mA load, MAX1556A -2.25 % No load -0.75 +2.25 300mA load -1.5 +1.5 T = -40C to +85C A (Note 3) 600mA load -2.25 +0.50 1200mA load, MAX1556 -4.0 -1.0 MAX1556/MAX1556A 1200 Maximum Output Current mA MAX1557 600 T = +25C 0.01 0.1 A D1 = D2 = GND OUT Bias Current MAX1556/MAX1557 A T = +85C 0.01 A For preset output voltages 3 4.5 D1 = D2 = GND, No load -0.50 +0.75 +1.75 V = 0.75V at OUT 300mA load -1.2 0 +1.2 300mA (typ), 600mA load -1.75 -0.75 +0.25 T = 0C to +85C A MAX1556/MAX1557 1200mA load, MAX1556 only -3.25 -2.25 -1.25 FB Threshold Accuracy % D1 = D2 = GND, No load -1.25 +2.25 V = 0.75V OUT 300mA load -1.75 +1.50 at 300mA (typ), 600mA load -2.75 +0.25 T = -40C to +85C A 1200mA load, MAX1556 only -4.25 -1.00 MAX1556/MAX1557 2 MAX1556/MAX1556A/MAX1557