Part: MAX1556/MAX1556A/MAX1557 — Maxim Integrated Products

Type: Synchronous Buck Converter

Description: Low-operating-current (16 μA), fixed-frequency step-down regulators with up to 97% efficiency, 1 MHz PWM switching, and 1.2 A guaranteed output current (MAX1556/MAX1556A).

Operating Conditions:

• Supply voltage: 2.6–5.5 V
• Operating temperature: -40 to +85 °C
• Output voltage range: 0.75 V to V_IN

Absolute Maximum Ratings:

• Max supply voltage: 6.0 V
• Max junction temperature: +150 °C
• Max storage temperature: -65 to +150 °C

Key Specs:

• Quiescent supply current: 16 μA (typ)
• Quiescent supply current in dropout: 27 μA (typ)
• Shutdown supply current: 0.1 μA (typ)
• Maximum output current (MAX1556/MAX1556A): 1200 mA
• Maximum output current (MAX1557): 600 mA
• Internal oscillator frequency: 1 MHz (typ)
• p-Channel On-Resistance (MAX1556/MAX1556A, V_IN = 3.6V): 0.19 Ω (typ)
• n-Channel On-Resistance (V_IN = 3.6V): 0.27 Ω (typ)
• p-Channel Current-Limit Threshold (MAX1556/MAX1556A): 1.8 A (typ)

Features:

• Up to 97% Efficiency
• 95% Efficiency at 1mA Load Current
• Low 16 μA Quiescent Current
• 1MHz PWM Switching
• Selectable 3.3V, 2.5V, 1.8V, 1.5V, 1.3V, 1.2V, 1.0V, and Adjustable Output
• Voltage Positioning Optimizes Load-Transient Response
• Low 27 μA Quiescent Current in Dropout
• Low 0.1 μA Shutdown Current
• No External Schottky Diode Required
• Analog Soft-Start with Zero Overshoot Current

Applications:

• PDAs and Palmtop Computers
• Cell Phones and Smart Phones
• Digital Cameras and Camcorders
• Portable MP3 and DVD Players
• Hand-Held Instruments

Package:

• 10-pin TDFN-EP (3mm x 3mm)

PDAs and Palmtop Computers

Cell Phones and Smart Phones

Digital Cameras and Camcorders

Portable MP3 and DVD Players

Hand-Held Instruments

MAX1556ETB+T Pinout

Package: TDFN-10 (3mm × 3mm)

Notes

• TDFN-10 package with exposed pad (pin 7, PGND) for thermal management
• Pin diagram shows all three variants (MAX1556/MAX1556A/MAX1557) share identical pinout
• D1 and D2 are external boost diode connections for the charge pump topology

(VIN = VINP = V SHDN = 3.6V, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2)

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IN, INP, OUT, D2, SHDN

to GND ..........................-0.3V to +6.0V

SS, D1 to GND.............................................-0.3V to (VIN + 0.3V)

PGND to GND .......................................................-0.3V to +0.3V

LX Current (Note 1)...........................................................±2.25A

Output Short-Circuit Duration.....................................Continuous

Continuous Power Dissipation (TA = +70°C)

10-Pin TDFN (derate 24.4mW/°C above +70°C) .......1951mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range.............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

Soldering Temperature (reflow) .......................................+260°C

Note 1: LX has internal clamp diodes to GND and IN. Applications that forward bias these diodes should take care not to exceed the IC's 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.

As soon as the junction temperature of the MAX1556/MAX1556A/MAX1557 exceeds +160°C, the ICs go into thermal shutdown. In this mode the internal p-channel switch and the internal n-channel synchronous rectifier are turned off. The device resumes normal operation when the junction temperature falls below +145°C.

For the latest package outline information and land patterns, go to www.maxim-ic.com/packages . Note that a '+', '#', or '-' in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.

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