Datasheet

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General Description

The MAX1935 low-dropout linear regulator operates

from a 2.25V to 5.5V supply and delivers a guaranteed

500mA load current with low 175mV dropout. The high-

accuracy (±1.5%) output voltage is preset at an inter-

nally trimmed voltage or can be adjusted from 0.8V to

4.5V with an external resistive-divider.

An internal PMOS pass transistor allows low 210µA

supply current, making this device ideal for portable

equipment such as personal digital assistants (PDAs),

cellular phones, cordless phones, and other equip-

ment, including base stations and docking stations.

Other features include an active-low, power-OK output

that indicates when the output is out of regulation, a

0.02µA shutdown mode, short-circuit protection, and

thermal-shutdown protection. The MAX1935 comes in a

tiny 1.9W, 8-pin 3mm x 3mm thin QFN package.

Applications

Notebook Computers

Cellular and Cordless Telephones

PDAs

Palmtop Computers

Base Stations

USB Hubs

Docking Stations

Features

♦ Guaranteed 500mA Output Current

♦ Output Down to 0.8V

♦ Low 175mV Dropout at 500mA

♦ ±1.5% Output Voltage Accuracy

Preset at 1.5V

Adjustable from 0.8V to 4.5V

♦ Power-OK Output

♦ Low 210µA Ground Current

♦ 0.02µA Shutdown Current

♦ Thermal-Overload Protection

♦ Output Current Limit

♦ Tiny 1.9W, 8-Pin 3mm x 3mm Thin QFN Package

MAX1935

500mA, Low-Voltage Linear Regulator

in Tiny QFN

________________________________________________________________ Maxim Integrated Products 1

OUT

SET

GNDSHDN

POK

MAX1935

THIN QFN

3mm x 3mm

TOP VIEW

Pin Configuration

Ordering Information

OUT

SET

GND

SHDN

POK

OUT

10µF

OUT

0.8V TO 4.5V

1µF

OFF

MAX1935

TO µC

POK

100kΩ

2.25V TO 5.5V

Typical Operating Circuit

19-2599; Rev 0; 10/02

PART T EM P R A N G E PIN-PACKAGE

MAX1935ETA* -40°C to +85°C

8 Thin QFN

3mm x 3mm

MAX1935ETA15* -40°C to +85°C

8 Thin QFN

3mm x 3mm

Selector Guide

PART

O U T PU T

VO L T A G E

TOP MARK

MAX1935ETA Adjustable ADB

MAX1935ETA15 1.5V ADB

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

*Contact factory for preset output voltages.

Summary of content (10 pages)

PAGE 1
9-2599; Rev 0; 10/02 500mA, Low-Voltage Linear Regulator in Tiny QFN An internal PMOS pass transistor allows low 210µA supply current, making this device ideal for portable equipment such as personal digital assistants (PDAs), cellular phones, cordless phones, and other equipment, including base stations and docking stations. Other features include an active-low, power-OK output that indicates when the output is out of regulation, a 0.
PAGE 2
MAX1935 500mA, Low-Voltage Linear Regulator in Tiny QFN ABSOLUTE MAXIMUM RATINGS IN, SHDN, POK, SET to GND ...................................-0.3V to +6V OUT to GND ................................................-0.3V to (VIN + 0.3V) Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (TA = +70°C) 8-Pin Thin QFN (derate 24.4mW/°C above +70°C) .......1.95W Operating Temperature .......................................
PAGE 3
500mA, Low-Voltage Linear Regulator in Tiny QFN (VIN = VOUT(SETPOINT) + 500mV or VIN = 2.25V whichever is greater, SET = GND, SHDN = IN, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5 50 mV 5.5 V 100 nA 96 % POWER-OK POK Output Low Voltage VOL Operating Voltage Range for Valid POK Output Sinking 2mA Sinking 100µA 1.0 Output High Leakage Current VPOK = 5.
PAGE 4
ELECTRICAL CHARACTERISTICS (continued) (VIN = VOUT(SETPOINT) + 500mV or VIN = 2.25V whichever is greater, SET = GND, SHDN = IN, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 50 mV 5.5 V 100 nA 97 % POWER-OK POK Output Low Voltage VOL Sinking 2mA Operating Voltage Range for Valid POK Output Sinking 100µA 1.0 Output High Leakage Current VPOK = 5.
PAGE 5
00mA, Low-Voltage Linear Regulator in Tiny QFN GROUND-PIN CURRENT vs. LOAD CURRENT 350 VIN = 3.8V 300 250 200 190 MAX1935 toc09 -60 MAX1935 toc08 VIN = VOUT + 500mV IOUT = 0 -50 -40 PSRR (dB) VIN = 5.5V GROUND-PIN CURRENT (µA) 450 180 170 -30 -20 160 -10 COUT = 10µF IOUT = 50mA 150 0 150 100 -40 -15 100 200 300 400 500 600 700 800 10 35 60 0.01 85 0.1 1 10 100 1000 FREQUENCY (kHz) TEMPERATURE (°C) LOAD CURRENT (mA) OUTPUT SPECTRAL NOISE DENSITY vs.
PAGE 6
MAX1935 500mA, Low-Voltage Linear Regulator in Tiny QFN Typical Operating Characteristics (continued) (VOUT = 3.3V, VIN = VOUT + 500mV, SHDN = IN, CIN = 1µF, COUT = 10µF, TA = +25°C, unless otherwise noted.) LOAD-TRANSIENT RESPONSE NEAR DROPOUT LINE-TRANSIENT RESPONSE MAX1935 toc15 MAX1935 toc14 6V VIN 1V/div IOUT 200mA/div 3V VOUT 50mV/div VIN = VOUT + 100mV CIN = 10µF ROUT = 660Ω TO 6.
PAGE 7
500mA, Low-Voltage Linear Regulator in Tiny QFN The MAX1935 is a low-dropout, low-quiescent-current linear regulator. The device supplies loads up to 500mA and is available with preset output voltages. As illustrated in Figure 1, the MAX1935 includes a 0.8V reference, error amplifier, P-channel pass transistor, and internal feedback voltage-divider. The reference is connected to the error amplifier, which compares it with the feedback voltage and amplifies the difference.
PAGE 8
MAX1935 500mA, Low-Voltage Linear Regulator in Tiny QFN VIN 2.25V TO 5.5V IN CIN 1µF IN THERMAL SENSOR MOSFET DRIVER WITH ILIM PRESET MODE OUT ON VOUT 0.8V TO 3.3V SHDN OUT OFF SHUTDOWN LOGIC COUT 10µF VREF 0.8V ERROR AMPLIFIER LOGIC SUPPLY VOLTAGE (VOUT) RPOK 100kΩ MAX1935 POK TO µC SET 93% VREF 80mV GND Figure 1. Functional Diagram a direct heat conduction path from the die to the PC board.
PAGE 9
500mA, Low-Voltage Linear Regulator in Tiny QFN MAX1935 600 IN OUT IN OUT 0.8V VIN +2.25V TO +5.5V -1 VOUT CIN 1µF COUT 10µF MAX1935 R1 ON SHDN TA = +70°C MAXIMUM OUTPUT CURRENT (A) R1 = R2 VOUT 500 400 TA = +85°C 300 200 100 SET OFF 0 0 R2 POK GND 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT-OUTPUT VOLTAGE DIFFERENCE (V) Figure 3. Power Operating Regions: Maximum Output Current vs. Input-Output Voltage Difference Figure 2.
PAGE 10
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) 6, 8, &10L, QFN THIN.EPS MAX1935 500mA, Low-Voltage Linear Regulator in Tiny QFN PACKAGE OUTLINE, 6, 8 & 10L, QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm 21-0137 C COMMON DIMENSIONS SYMBOL A MIN. 0.70 MAX. 0.80 D 2.90 3.10 E 2.90 3.10 A1 0.00 0.05 L k 0.20 0.40 0.25 MIN A2 0.20 REF.