MAX1556/MAX1556A/MAX1557

Part: MAX1556ETB+T — Maxim Integrated (MAX1556/MAX1556A/MAX1557 family)

Type: Synchronous PWM Step-Down DC-DC Converter

Description: 2.6–5.5 V input, 1.2 A (MAX1556/MAX1556A) or 600 mA (MAX1557) synchronous step-down converter with 16 μA quiescent current, 1 MHz fixed-frequency PWM, and up to 97% efficiency.

Operating Conditions:

• Supply voltage: 2.6–5.5 V
• Operating temperature: -40 to +85 °C
• Output voltage range: 0.75 V to VIN (adjustable); pin-selectable presets
• Switching frequency: 1 MHz (typ)

Absolute Maximum Ratings:

• Max supply voltage: IN, INP, OUT, D2, SHDN to GND: -0.3 V to +6.0 V
• LX current: ±2.25 A
• Max junction temperature: +150 °C
• Storage temperature: -65 to +150 °C

Key Specs:

• Quiescent supply current: 16 μA typ, 25 μA max (no switching, D1 = D2 = GND); 27 μA typ in dropout
• Shutdown supply current: 0.1 μA typ, 1 μA max (TA = +25 °C)
• Maximum output current: 1200 mA (MAX1556/MAX1556A), 600 mA (MAX1557)
• Undervoltage lockout: 2.35 V typ (2.20–2.55 V), 35 mV hysteresis
• p-channel on-resistance (MAX1556/MAX1556A): 0.19 Ω typ, 0.35 Ω max (VIN = 3.6 V)
• n-channel on-resistance: 0.27 Ω typ, 0.48 Ω max (VIN = 3.6 V)
• p-channel current limit (MAX1556/MAX1556A): 1.5–2.1 A (1.8 A typ)
• Internal oscillator frequency: 0.9–1.1 MHz
• Thermal shutdown: +160 °C, 15 °C hysteresis

Features:

• Up to 97% efficiency; 95% at 1 mA load
• Pin-selectable outputs: 3.3 V, 2.5 V, 1.8 V (MAX1556); 1.5 V, 1.3 V, 1.0 V (MAX1557); 1.2 V and 1.5 V (MAX1556A); also adjustable
• Voltage positioning for optimized load-transient response
• 100% duty-cycle dropout operation
• Adjustable analog soft-start with zero overshoot current
• No external Schottky diode required
• Works with a tiny 3.3 μH inductor

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, 3 mm x 3 mm

PDAs and Palmtop Computers

Cell Phones and Smart Phones

Digital Cameras and Camcorders

Portable MP3 and DVD Players

Hand-Held Instruments

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Maxim Integrated Products

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For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.

Features

(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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