Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - LDO voltage regulator Positivbe, adjustable TQFN 16 (5x5)

General Description

The MAX8556/MAX8557 low-dropout linear regulators

operate from input voltages as low as 1.425V and are

able to deliver up to 4A of continuous output current

with a typical dropout voltage of only 100mV. The out-

put voltage is adjustable from 0.5V to V

- 0.2V.

Designed with an internal p-channel MOSFET pass tran-

sistor, the MAX8556/MAX8557 maintain a low 800µA typi-

cal supply current, independent of the load current and

dropout voltage. Using a p-channel MOSFET eliminates

the need for an additional external supply or a noisy inter-

nal charge pump. Other features include a logic-con-

trolled shutdown mode, built-in soft-start, short-circuit

protection with foldback current limit, and thermal-over-

load protection. The MAX8556 features a POK output that

transitions high when the regulator output is within ±10%

of its nominal output voltage. The MAX8557 offers a

power-on reset output that transitions high 140ms after the

output has achieved 90% of its nominal output voltage.

The MAX8556/MAX8557 are available in a 16-pin thin

QFN 5mm x 5mm package with exposed paddle.

Applications

Servers and Storage Devices

Networking

Base Stations

Optical Modules

Point-of-Load Supplies

ATE

Features

o 1.425V to 3.6V Input Voltage Range

o Guaranteed 4A Output Current

o ±1% Output Accuracy Over Load/Line/

Temperature

o 100mV Dropout at 4A Load (typ)

o Built-In Soft-Start

o 800µA (typ) Operating Supply Current

o 150µA (max) Shutdown Supply Current

o Short-Circuit Current Foldback Protection

o Thermal-Overload Protection

o ±10% Power-OK (MAX8556)

o 140ms Power-On Reset Output (MAX8557)

o Fast Transient Response

o 16-Pin Thin QFN (5mm x 5mm) Package

MAX8556/MAX8557

4A Ultra-Low-Input-Voltage

LDO Regulators

________________________________________________________________

Maxim Integrated Products

12 11 10 9

OUT

TOP VIEW

N.C.

GND

1234

MAX8556

(MAX8557)

POK (POR)

OUT

THIN QFN

5mm x 5mm

Pin Configuration

Ordering Information

GND

OUT

N.C.

POK

(POR)

1.425V TO 3.6V

OUT

0.5V TO V

- 0.2V

MAX8556

(MAX8557)

Typical Operating Circuit

19-3257; Rev 2; 8/09

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.

EVALUATION KIT

AVAILABLE

PART

TEMP

RANGE

PIN-

PACKAGE

FEATURE

MAX8556ETE+ - 40°C to + 85°C 16 Thin QFN-EP* POK

M AX 8556E TE /V + - 40°C to + 85°C 16 Thin QFN-EP* POK

MAX8557ETE+ - 40°C to + 85°C 16 Thin QFN-EP* POR

Denotes a lead(Pb)-free/RoHS-compliant package.

/V Denotes an automotive qualified part.

*EP = Exposed pad.

Summary of content (10 pages)

PAGE 1
9-3257; Rev 2; 8/09 KIT ATION EVALU E L B AVAILA 4A Ultra-Low-Input-Voltage LDO Regulators The MAX8556/MAX8557 low-dropout linear regulators operate from input voltages as low as 1.425V and are able to deliver up to 4A of continuous output current with a typical dropout voltage of only 100mV. The output voltage is adjustable from 0.5V to VIN - 0.2V.
PAGE 2
MAX8556/MAX8557 4A Ultra-Low-Input-Voltage LDO Regulators ABSOLUTE MAXIMUM RATINGS IN, EN, POK, POR to GND .......................................-0.3V to +4V FB, OUT to GND ..........................................-0.3V to (VIN + 0.3V) Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (TA = +70°C) 16-Pin Thin QFN (derate 33.3mW/°C above +70°C) (Note 1)............................................2666.7mW Operating Temperature Range .................
PAGE 3
4A Ultra-Low-Input-Voltage LDO Regulators (VEN = VIN = 1.8V, VOUT = 1.5V, IOUT = 2mA, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) (Note 2) PARAMETER CONDITIONS POK Output Current, High VPOK = 3.6V VFB = 0.5 POK Delay Time From FB rising to POK high MIN 25 TYP MAX UNITS 0.001 1 µA 50 100 µs EN Enable Input Threshold VIN = 1.425V to 3.6V Enable Input Bias Current VEN = 0V or 3.6V EN rising 1.25 EN falling V 0.
PAGE 4
Typical Operating Characteristics (continued) (VEN = VIN = +1.8V, VOUT = +1.5V, IOUT = 4A, COUT = 20µF, CIN = 20µF, and TA = +25°C, unless otherwise noted.) DROPOUT VOLTAGE vs. LOAD CURRENT GND CURRENT vs. TEMPERATURE 700 ILOAD = 2A 600 500 400 80 DROPOUT VOLTAGE (mV) 800 ILOAD = 0A 300 70 30 10 0 0 35 60 VIN 40 100 10 2.5V 50 20 -15 MAX8556 toc06 1.
PAGE 5
4A Ultra-Low-Input-Voltage LDO Regulators PSRR vs. FREQUENCY STARTUP WAVEFORMS MAX8556 toc12 MAX8556 toc11 90 80 70 2V/div PSRR (dB) 60 VIN 2A/div 50 40 IIN 30 1V/div 20 VOUT VIN = 2.5V ILOAD = 1A 10 0 1 10 1000 100 100µs/div FREQUENCY (kHz) EXPOSED PADDLE TEMPERATURE vs. AMBIENT TEMPERATURE FB REGULATION vs. TEMPERATURE 90 80 MAX8556 toc14 0.510 MAX8556 toc13 0.505 70 FB (V) 60 50 0.500 40 30 0.495 20 DATA TAKEN USING MAX8556 EVALUATION KIT 10 ILOAD = 50mA 0.
PAGE 6
4A Ultra-Low-Input-Voltage LDO Regulators MAX8556/MAX8557 Pin Description PIN NAME FUNCTION 1–6 IN LDO Input. Connect to a 1.425V to 3.6V input voltage. Bypass with a 22µF ceramic capacitor to GND. 7–11 OUT LDO Output. Bypass with 2 x 10µF ceramic capacitors to GND. A smaller capacitance can be used if the maximum load current is less than 4A. POK (MAX8556) Power-OK Output. Open-drain output that pulls low when VOUT is outside ±10% of the expected regulation voltage or when EN is low.
PAGE 7
4A Ultra-Low-Input-Voltage LDO Regulators The MAX8556/MAX8557 low-dropout linear regulators are capable of delivering up to 4A from low-input voltage supplies ranging from 1.425V to 3.6V with only 200mV of dropout (max). The pMOS output stage can be driven from input voltages down to 1.425V without sacrificing stability or transient performance. Supply current is not a significant function of load or input headroom because this regulator has a pMOS output device.
PAGE 8
MAX8556/MAX8557 4A Ultra-Low-Input-Voltage LDO Regulators Applications Information Output Voltage Selection The MAX8556/MAX8557 feature an adjustable output voltage from 0.5V to 3.4V. Set the output voltage using an external resistor-divider from the output to GND with FB connected to the center tap as shown in Figures 1 and 2. Choose R3 ≤ 1kΩ for light-load stability. Determine R2 using the following equation: ⎛V ⎞ R2 = R 3 x ⎜ OUT − 1⎟ ⎝ VFB ⎠ VIN 1.425V TO 3.
PAGE 9
4A Ultra-Low-Input-Voltage LDO Regulators How much power the package can dissipate strongly depends on the mounting method of the IC to the PCB and the copper area for cooling. Using the JEDEC test standard, the maximum power dissipation allowed in the package is 2667mW. This data is obtained with +70°C ambient temperature and +150°C maximum junction temperature. The test board has dimensions of 3in x 3in with four layers of 2oz copper and FR-4 material with 62mil finished thickness.
PAGE 10
MAX8556/MAX8557 4A Ultra-Low-Input-Voltage LDO Regulators Revision History REVISION NUMBER REVISION DATE 0 4/04 Initial release — 1 8/08 Revised Pin Configuration. 1 2 8/09 Added automotive version of the MAX8556. 1 DESCRIPTION PAGES CHANGED Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.