Maxim MAX1935ETA Schematic [ru]

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 high­accuracy (±1.5%) output voltage is preset at an inter­nally 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 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

0.02µA 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

Pin Configuration

Ordering Information

OUT

SET

GND

IN

SHDN

POK

C

OUT

10µF

V

OUT

0.8V TO 4.5V

C

IN

1µF

ON

OFF

R

2

MAX1935

R

1

TO µC

R

POK

100kΩ

V

IN

2.25V TO 5.5V

Typical Operating Circuit

19-2599; Rev 0; 10/02

Selector Guide

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.

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

MAX1935ETA* -40°C to +85°C

MAX1935ETA15* -40°C to +85°C

PART

MAX1935ETA Adjustable ADB

MAX1935ETA15 1.5V ADB

8 Thin QFN
3mm x 3mm

8 Thin QFN
3mm x 3mm

O U T PU T

VO L T A G E

TOP MARK

TOP VIEW

IN

IN

POK

OUT

1

2

MAX1935

3

4

THIN QFN

3mm x 3mm

8

OUT

7

SET

6

GNDSHDN

5

MAX1935

500mA, Low-Voltage Linear Regulator
in Tiny QFN

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= V

OUT(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 T

A

= +25°C.)

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.

IN, SHDN, POK, SET to GND ...................................-0.3V to +6V

OUT to GND ................................................-0.3V to (V

IN

+ 0.3V)

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

Continuous Power Dissipation (T

A

= +70°C)

8-Pin Thin QFN (derate 24.4mW/°C above +70°C) .......1.95W

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

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

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

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

Dual Mode is a trademark of Maxim Integrated Products, Inc.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input Voltage V

Input Undervoltage Lockout V

Output Voltage Accuracy
(Preset Mode)

Adjustable Output Voltage

SET Voltage Threshold
(Adjustable Mode)

Maximum Output Current I

Short-Circuit Current Limit I

SET Dual Mode™ Threshold 35 80 125 mV

SET Input Bias Current I

Ground-Pin Current I

Line Regulation ∆V
Load Regulation ∆V

Output Voltage Noise 10Hz to 1MHz, C

SHUTDOWN

Shutdown Supply Current I

S HDN Input Threshold

S HDN Input Bias Current I

Startup Time t

IN

UVLO

V

OUT

V

SET

OUT

LIM

SET

OFF

V

V

SHDN

STARTC OUT

Rising, 40mV hysteresis 1.85 2 2.15 V

TA = +25°C, I

TA = +25°C, I

OUT

OUT

TA = 0°C to +85°C, I

> V

OUT

+ 0.5V

OUT

OUT

V

IN

TA = +25°C, I

TA = +25°C, I

TA = 0°C to +85°C, I
V

> V

IN

V

OUT

V

SET

I

OUT

Q

I

OUT

OUT

LNRV I N

LDRIOUT

+ 0.5V

OUT

= 0V 600 1400 2300 mA

= 0.8V -100 +100 nA

= 1mA 210 600

= 500mA 575

= 500mA

fr om ( V

+ 100m V ) to 5.5V , I

OU T

= 1mA to 500mA 15.5 35 p p m /m A

S HDN = GND, VIN = 5.5V 0.02 5 µA

IH

IL

S HDN = GND or IN 10 100 nA

= 10µF, ti m e fr om S HDN hig h to P OK hig h40 µs

2.25 5.50 V

= 100mA -1.5 +1.5

= 1mA to 500mA -2.5 +2.5

= 1mA to 500mA,

OUT

-3 +3

0.8 4.5 V

= 100mA 788 812

= 1mA to 500mA 780 820

= 1mA to 500mA,

OUT

774 800 826

500 m A

V

= 2.25V 259 400

OUT

V

= 2.8V 201 350Dropout Voltage (Note 1) I

OUT

= 4V 147 275

V

OUT

= 5m A 0 0.125 %/V

L OA D

= 10µF (ESR < 0.1Ω) 300 µV

OUT

1.6

0.6

%

mV

RM S

µA

mV

RMS

V

MAX1935

500mA, Low-Voltage Linear Regulator

in Tiny QFN

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= V

OUT(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 T

A

= +25°C.)

ELECTRICAL CHARACTERISTICS

(VIN= V

OUT(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 T

A

= +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER-OK

POK Output Low Voltage V

Operating Voltage Range for
Valid POK Output

Output High Leakage Current V

Threshold Rising edge, referred to V

THERMAL PROTECTION

Ther m al- S hutd own Tem p erature T
Thermal-Shutdown Hysteresis ∆T

Sinking 2mA 5 50 mV

OL

Sinking 100µA 1.0 5.5 V

= 5.5V 100 nA

POK

OUT(NOMINAL)

SHDN

SHDN

90 93 96 %

170 °C

20 °C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input Voltage V

Input Undervoltage Lockout V

Output Voltage Accuracy
(Preset Mode)

Adjustable Output Voltage

SET Voltage Threshold
(Adjustable Mode)

Maximum Output Current I

Short-Circuit Current Limit I

SET Dual Mode Threshold 35 125 mV

SET Input Bias Current I

Ground-Pin Current I

SHUTDOWN

Shutdown Supply Current I

S HDN Input Threshold

S HDN Input Bias Current I

IN

UVLO

V

OUTIOUT

V

SETIOUT

OUT

LIM

SET

Q

OFF

V

IH

V

IL

SHDN

Rising, 40mV hysteresis 1.85 2.15 V

= 1mA to 500mA -4 +4 %

= 1mA to 500mA 766 834 mV

V

= 0V 600 2500 mA

OUT

V

= 0.8V -100 +100 nA

SET

I

= 1mA 400 µA

OUT

S HDN = GND, VIN = 5.5V 5 µA

2.5V < V

2.5V < V
S HDN = GND or IN 100 nA

< 5.5V 1.6

IN

< 5.5V 0.6

IN

2.25 5.50 V

0.8 4.5 V

500 m A

RM S

V

MAX1935

500mA, Low-Voltage Linear Regulator
in Tiny QFN

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VIN= V

OUT(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 T

A

= +25°C.) (Note 2)

Note 1: Dropout voltage is defined as VIN- V

OUT

, when V

OUT

is 100mV below the value of V

OUT

and when VIN= V

OUT(NOM)

+ 0.5V.

For 2.25V ≤ V

OUT

≤ 4V, dropout voltage limits are linearly interpolated from the values listed. For V

OUT

< 4V, dropout

voltage limit is equal to the value for V

OUT

= 4V.

Note 2: Specifications to -40°C are guaranteed by design, not production tested.

Typical Operating Characteristics

(V

OUT

= 3.3V, VIN= V

OUT

+ 500mV, SHDN = IN, CIN= 1µF, C

OUT

= 10µF, TA= +25°C, unless otherwise noted.)

0

1.0

0.5

2.0

1.5

3.0

2.5

3.5

1.5 2.5 3.02.0 3.5 4.0 4.5 5.0 5.5

OUTPUT VOLTAGE vs. INPUT VOLTAGE

MAX1935 toc01

INPUT VOLTAGE (V)

OUTPUT VOLTAGE (V)

I

OUT

= 0mA

I

OUT

= 500mA

6.0

3.25

3.26

3.28

3.27

3.30

3.31

3.29

3.32

0 200 300100 400 500 600 700 800

OUTPUT VOLTAGE vs. LOAD CURRENT

MAX1935 toc02

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

3.28

3.30

3.29

3.32

3.31

3.33

3.34

-40 10-15 35 60 85

OUTPUT VOLTAGE vs. TEMPERATURE

MAX1935 toc03

TEMPERATURE (°C)

OUTPUT VOLTAGE (V)

VIN = V

OUT

+ 500mV

I

OUT

= 0

0

100

50

200

150

250

300

350

400

0 200 300100 400 500 600 700 800

DROPOUT VOLTAGE vs. LOAD CURRENT

MAX1935 toc04

LOAD CURRENT (mA)

DROPOUT VOLTAGE (mV)

TA = +85°C

TA = +25°C

TA = -40°C

0.14

0.16

0.18

0.20

0.22

0.24

0.26

0.28

2.0 2.5 3.0 3.5 4.0 4.5

DROPOUT VOLTAGE

vs. OUTPUT VOLTAGE

MAX1935 toc05

OUTPUT VOLTAGE (V)

DROPOUT VOLTAGE (V)

0

100

50

150

200

250

300

350

400

450

500

550

600

2.0 3.0 4.0 5.0 6.0

GROUND-PIN CURRENT

vs. INPUT VOLTAGE

MAX1935 toc06

INPUT VOLTAGE (V)

GROUND-PIN CURRENT (µA)

3.52.5 4.5 5.5

I

OUT

= 0mA

I

OUT

= 500mA

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER-OK

POK Output Low Voltage V

Operating Voltage Range for
Valid POK Output

Output High Leakage Current V

Threshold Rising edge, referred to V

Sinking 2mA 50 mV

OL

Sinking 100µA 1.0 5.5 V

= 5.5V 100 nA

POK

OUT(NOMINAL)

89 97 %