Maxim MAX689CSA, MAX689CUA, MAX689EPA, MAX688CSA, MAX688EPA Datasheet

19-0329; Rev 0; 12/94

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

High-Accuracy, Low-Dropout

Linear Regulators

_______________General Description

The MAX687/MAX688/MAX689 low-dropout linear regula­tors operate with an input-to-output voltage differential lim­ited only by an external PNP transistor. Outputs are fixed
at 3.3V (MAX687/MAX688) or 3.0V (MAX689). The only
external components required are a PNP pass transistor
and output, compensation, and bypass capacitors. Base
drive to the external transistor is at least 10mA, permitting
output currents to exceed 1A when using high-gain tran­sistors (β > 100). Output current limiting is implemented
by limiting the external transistor’s base current. Output
voltage monitoring and shutdown functions are included.

The 3.3V MAX687 automatically shuts down whenever
the output voltage drops below 2.96V. An internal
power-fail comparator also monitors the output and pro­vides an early warning of low output voltage before the
device shuts down. When shut down, the output is
latched off until the ON input is pulsed. Turning off the
power supply in this way prevents battery damage due
to excessive discharge or cell-reversal. Typical applica­tions include portable telephones and other battery-pow­ered equipment where the power supply must be
disabled when the battery voltage is low.

The MAX688 and MAX689 do not have an automatic
shutdown function, and are identical except for their
output voltages. Each device has an active-low shut­down-control input, used to turn its output on or off at
any time. As SHDN falls, the device enters a standby
mode before fully shutting down. When in standby, the
reference and comparators are fully operational, per­mitting the transition from normal mode to standby
mode to occur at a precise voltage level on SHDN.

________________________Applications

High-Efficiency Linear Regulator
Battery-Powered Devices
Portable Instruments
Portable Telephones
Power Supply or Backup Supply for Memory

__________________Pin Configuration

____________________________Features

♦ Fixed Outputs:

3.3V (MAX687/MAX688)

3.0V (MAX689)

♦ Directly Drives External PNP Transistor
♦ 10mA Min Base-Current Drive for >1A Output
♦ Low Dropout Voltage:

100mV Dropout at 650mA Output (FZT749)
40mV Dropout at 200mA Output (FZT749)

0.8V Dropout at 4A Output

♦ Power-Fail Output Monitors the Output Voltage
♦ Automatic, Latched Shutdown when Output Falls Out

of Regulation (MAX687)

♦ Precision Threshold Shutdown Control

(MAX688/MAX689)

♦ Low Supply Current:

150µA Operating
<1µA Shutdown

♦ 2.7V to 11.0V Supply Range
♦ 8-Pin DIP/SO/µMAX Packages
♦ <2mV Line Transient with 3.4V to 3.6V Input
♦ Output Accuracy <±2%

______________Ordering Information

PART

MAX687CPA

MAX687CSA
MAX687CUA 0°C to +70°C
MAX687EPA
MAX687ESA -40°C to +85°C

Ordering Information continued at end of data sheet.

TEMP. RANGE PIN-PACKAGE

0°C to +70°C
0°C to +70°C

-40°C to +85°C 8 Plastic DIP

8 Plastic DIP
8 SO
8 µMAX

8 SO

__________Typical Operating Circuit

+3.5V to +5V INPUT

Q1

FZT749

12Ω



R

B

3.3V @ 500mA

MAX687/MAX688/MAX689

TOP VIEW

(ON) SHDN

( ) ARE FOR MAX687

IN

1
2

MAX687
MAX688

3

PFO

GND

MAX689

4

DIP/SO/µMAX

________________________________________________________________

CC

8

BASE

7

BLIM

6

OUT

5

2.2µF

ON

C1

GND

BASE

IN

ON

BLIM

MAX687

GND

Maxim Integrated Products

Call toll free 1-800-998-8800 for free samples or literature.

OUT

PFO

C2

68µF

POWER-FAIL

OUTPUT

CC

C3
10nF

1

High-Accuracy, Low-Dropout
Linear Regulators

ABSOLUTE MAXIMUM RATINGS

Input Supply Voltage IN to GND............................................12V

Terminal Voltages to GND

(MAX687)........................................-0.3V to V

PFO

(MAX688/MAX689) ......................................-0.3V to 12V

PFO

All Remaining Pins .....................................-0.3V to V

Sink Current ...............................................................10mA

PFO

Source Current (MAX687)...........................................10mA

PFO

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.

OUT

IN

+ 0.3V
+ 0.3V

Continuous Power Dissipation (T

Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW

SO (derate 5.88mW/°C above +70°C).........................471mW

µMAX (derate 4.1mW/°C above +70°C) ......................330mW

Operating Temperature Ranges

MAX68_C_A .......................................................0°C to +70°C

MAX68_E_A ....................................................-40°C to +85°C

Storage Temperature Range.............................-65°C to +165°C

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

ELECTRICAL CHARACTERISTICS

(VIN= 3.8V, SHDN = VIN(MAX688/MAX689), RB= 0Ω, C1 = 2.2µF, C2 = 10µF, C3 = 10nF, TA= T
noted. Typical values are at T

LINEAR REGULATOR

Supply Voltage

MAX687/MAX688/MAX689

Output Voltage

Dropout Voltage (Note 2)

Line Regulation

Supply Current

BASE Sink Current

Base-Current Limit

= +25°C.)

A

V

OUT

I

GND

BASE

CONDITIONS

(Note 1)

IN

MAX687/MAX688

MAX689

PNP = FZT749, I

OUT

MAX687/MAX688

MAX689
1µA ≤ I

VIN= 3.8V,
PNP = FZT749,
no load

V

BASE

RBis connected from BASE to BLIM (Ω),
RB= 0Ω to 100Ω

(Note 3)

PNP = FZT749, I

≤ 10mA

BASE

= VIN- 1V

= 200mA, C2 = 20µF

LOAD

= 100mA (Note 4)

LOAD

VIN= 3.8V, I

3.8V ≤ VIN≤ 11.0V,
1µA ≤ I

VIN= 3.5V, I

3.5V ≤ VIN≤ 11.0V,
1µA ≤ I

3.8V ≤ VIN≤ 11.0V,
I

= 1mA

BASE

3.5V ≤ VIN≤ 11.0V,
I

= 1mA

BASE

On
Standby,

MAX688/MAX689
Shutdown

BASE

BASE

BASE

≤ 10mA

BASE

≤ 10mA

= 1mA

= 1mA

= +70°C)

A

to T

MIN

3.2 3.3 3.4

3.13 3.3 3.47

2.9 3.0 3.1

2.85 3.0 3.15

70 100 130

+ 5Ω RB+ 5Ω RB+ 5Ω

R

B

, unless otherwise

MAX

0.4 1.4

0.4 1.4

150 250

11 25

< 0.02 1

UNITSMIN TYP MAXSYMBOLPARAMETER

V2.7 11.0V

V

mV40VIN- V

mV/V

mV45 60Load Regulation

µA

mA10 20 40I

mA

µs300Start-Up Time

%2Start-Up Overshoot

µF10C2Load Capacitance

2 _______________________________________________________________________________________

High-Accuracy, Low-Dropout

Linear Regulators

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 3.8V, SHDN = VIN(MAX688/MAX689), RB= 0Ω, C1 = 2.2µF, C2 = 10µF, C3 = 10nF, TA= T
noted. Typical values are at T

= +25°C.)

A

CONDITIONS

MAX687: ON, PFO, SHDN

V

PFT

NOM

V

PFT

SD
OH
OL

-

- V

SD

IH
IL

Falling V

Falling V
Falling V

I

SOURCE

I

SINK

, comparators monitor V

OUT

, comparators monitor V

OUT

, comparators monitor V

OUT

= 50µA, part on, VIN= 2.7V VV

= 1.2mA, VIN= 2.7V V0.06 0.3V
Output turns on
Output remains off 0.2V

OUT

OUT

OUT

PFO Threshold Voltage Below
V

(Note 5)

NOM

Shutdown Threshold Voltage
Below V

PFT

Shutdown Threshold Voltage
PFO Output Voltage High
PFO Output Voltage Low

ON Threshold Voltage

MAX688/MAX689: SHDN, PFO

PFO Threshold Voltage

SHDN Threshold Voltages

V

PFT

SON

SSY

SSD

Falling V
parators monitor V

OUT

, com-

On, SHDN falling
Standby
Shutdown

MAX688

OUT

MAX689 2.77 2.85 2.89

Rising SHDN, standby→on
V

= 1.23V nA-25 25SHDN Input Current

SHDN

Glitch immunity
I

PFO Output Voltage Low

OL

PFO Off Leakage Current
Output Noise Voltage

Note 1: Minimum VINfor regulated V

ence and comparators are functional down to the minimum voltage specified, but the output may not be in regulation.

Note 2: Dropout voltage is defined as V
Note 3: The start-up time specification is the time taken from ON or SHDN

e

n

depends on the characteristics of the external PNP transistor, and on the load. The refer-

OUT

- V

IN

and is a function of load capacitance, C2, and load resistance, R

Note 4: Minimum load capacitance is a function of RL. Minimum C2 = 10µF for loads up to 100mA and 1µF/10mA for higher loads.

ESR of C2 should be no larger than 1/100 of R

Note 5: The nominal output voltage, V

, is defined under the default conditions of testing: VIN= 3.8V, I

NOM

= 1.2mA, VIN= 2.7V

SINK

V

= 11V, V

PFO

10Hz ≤ f ≤ 10kHz, I
10Hz ≤ f ≤ 1MHz, I

when V

OUT

OUT

. Guaranteed by design.

L

> 1.25V

SHDN

= 200mA

LOAD

= 200mA

LOAD

is 50mV below its value at VIN= V

rising to BASE sinking current. V

.

L

NOM

to T

, unless otherwise

MAX

OUT

MIN

- 0.3V

1.0V

3.07 3.13 3.19

1.25V

1.0 1.2V

0.2V

66

105

+ 1V.

rise time is longer

OUT

= 1mA, TA= T

BASE

MIN

UNITSMIN TYP MAXSYMBOLPARAMETER

µV

to T

MAX687/MAX688/MAX689

mV110 170
mV7PFO Hysteresis
mV20 70V

V2.96V

V

nA0.2 100ON Input Leakage Current

V

mV7PFO Hysteresis

V

mV70SHDN Hysteresis

µs100PFO, SHDN Transient Rejection

V0.06 0.3V

µA1

RMS

.

MAX

_______________________________________________________________________________________ 3

High-Accuracy, Low-Dropout
Linear Regulators

__________________________________________Typical Operating Characteristics

(Circuits of Figures 1 and 2, VIN= 5V, Q1 = FZT749, TA = +25°C, unless otherwise noted.)

MAX689

50 100 250200150

NUMBER OF UNITS

OUTPUT VOLTAGE DISTRIBUTION

3.32289

3.31932

3.31576

3.31219

3.30862

3.30505

3.30149

3.29792

OUTPUT VOLTAGE (V)

3.29435

3.29078

3.28722

3.28365

0 50 100 250200150

MAX687

NUMBER OF UNITS

3.32145

3.31920

3.31696

MAX687/9-02

3.31472

3.31248

3.31024

3.30800

3.30576

3.30352

3.30128

3.29904

OUTPUT VOLTAGE (V)

3.29679

3.29455

3.29231

3.29007

3.28783

OUTPUT VOLTAGE DISTRIBUTION

MAX688

0 50 100

NUMBER OF UNITS

MAX687/9-01

250200150

OUTPUT VOLTAGE DISTRIBUTION

3.01595

3.01420

3.01245

3.01071

3.00896

3.00721

3.00547

3.00372

3.00198

3.00023

OUTPUT VOLTAGE (V)

2.99848

2.99674

2.99499

2.99324

2.99150

2.98975

0

MAX687/9-03

DROPOUT VOLTAGE 

0.30

vs. LOAD CURRENT

Q1 = FZT749
RB = 0Ω

0.25

MAX687/MAX688/MAX689

0.20

(V)

OUT

0.15

- V

IN

V

0.10

0.05

0

0 200 600 1000 1400 1800

OBSERVE MAXIMUM POWER
DISSIPATION LIMIT OF 
EXTERNAL PASS TRANSISTOR.

MAX687/9-05

1.0

0.9

0.8

0.7

(V)

0.6

OUT

0.5

- V

IN

0.4

V

0.3

0.2

0.1
0

LOAD CURRENT (mA)

GND CURRENT vs. DROPOUT VOLTAGE

7
6

5

4

3

GND CURRENT (mA)

2

1

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

300mA LOAD

100mA LOAD

VIN - V

OUT

10mA LOAD

(V)

MAX687/9-7

GND CURRENT (mA)

7
6

5

4

3

2

1

0

DROPOUT VOLTAGE

vs. LOAD CURRENT

Q1 = 2N2907
RB = 0Ω

0 200 600 1000

400 800

LOAD CURRENT (mA)

GND CURRENT vs. DROPOUT VOLTAGE

300mA LOAD

100mA LOAD

0812345 76

VIN - V

OUT

10mA LOAD

(V)

GND CURRENT 

vs. LOAD CURRENT

6

MAX687/9-5

5

4

3

GND CURRENT (mA)

2

1

0

0 200 400 600 800 1000 1200

LOAD CURRENT (mA)

NO-LOAD SUPPLY CURRENT 

vs. TEMPERATURE

146
144

MAX687/9-8

142
140
138
136
134
132

SUPPLY CURRENT (µA)

130
128
126

-55 -25 0 25 50 75 100 125
TEMPERATURE (°C)

MAX687/9-06

MAX687/9-9

4 _______________________________________________________________________________________