Datasheet MAX8874TEUK-T, MAX8874SEUK-T, MAX8874REUK-T, MAX8873TEUK-T, MAX8873SEUK-T Datasheet (Maxim)

_______________General Description

The MAX8873T/S/R and MAX8874T/S/R low-dropout lin­ear regulators operate from a +2.5V to +6.5V input
range and deliver up to 120mA. A PMOS pass transis­tor allows the low, 82µA supply current to remain inde­pendent of load, making these devices ideal for
battery-operated portable equipment such as cellular
phones and cordless phones.

The devices feature Dual Mode™ operation: their out­put voltage is preset (at 3.15V for the T versions, 2.84V
for the S versions, or 2.80V for the R versions) or can be
adjusted with an external resistor divider. Total error on
the output is ±3.5%. Output voltages are set on the low
side of popular ranges so that power drain is minimized
for longer battery life. Other features include low-power
shutdown, short-circuit protection, thermal shutdown
protection, and reverse battery protection. The
MAX8874 also includes an auto-discharge function,
which actively discharges the output voltage to ground
when the device is placed in shutdown mode. Both
devices come in a miniature 5-pin SOT23 package.

For dual versions, refer to the MAX8865/MAX8866 data
sheet. For low-noise versions with 30µV

RMS

output

noise, refer to the MAX8877/MAX8878.

________________________Applications

Cordless Telephones Modems
PCS Telephones Hand-Held Instruments
Cellular Telephones Palmtop Computers
PCMCIA Cards Electronic Planners

____________________________Features

♦ LP2980 Pin-Compatible SOT23 Package
♦ Low, 55mV Dropout Voltage at 50mA I

OUT

(130mV at 120mA)

♦ Low, 73µA No-Load Supply Current

Low, 82µA Operating Supply Current (even in
dropout)

♦ Miniature External Components
♦ Thermal Overload Protection
♦ Output Current Limit
♦ Reverse Battery Protection
♦ Dual Mode Operation: Fixed or Adjustable

(1.25V to 6.5V) Output

♦ Low-Power Shutdown

MAX8873T/S/R, MAX8874T/S/R

Low-Dropout, 120mA Linear Regulators

________________________________________________________________

Maxim Integrated Products

1

SOT23-5

TOP VIEW

GND

SET

SHDN

1

5

OUT

IN

MAX8873
MAX8874

2

3

4

__________________Pin Configuration

MAX8873
MAX8874

OUT

GND SET

IN

SHDN

C

OUT

1µF

C

IN

1µF

BATTERY

OUTPUT
VOLTAGE

__________Typical Operating Circuit

19-1257; Rev 1; 3/98

PART

MAX8873TEUK-T

MAX8873SEUK-T

MAX8874TEUK-T

-40°C to +85°C

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE

PIN-

PACKAGE

5 SOT23-5
5 SOT23-5

5 SOT23-5

______________Ordering Information

SOT TOP

MARK

ABZH

ABZI

ABZJ

MAX8874SEUK-T -40°C to +85°C 5 SOT23-5 ABZK

Dual Mode is a trademark of Maxim Integrated Products.

MAX8873REUK-T -40°C to +85°C 5 SOT23-5 ABZL

MAX8874REUK-T -40°C to +85°C 5 SOT23-5 ABZM

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone].
For small orders, phone [phone] ext. 3468.

MAX8873T/S/R, MAX8874T/S/R

Low-Dropout, 120mA Linear Regulators

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= +3.6V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

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.

VINto GND ..................................................................-7V to +7V

Output Short-Circuit Duration ............................................Infinite

SET to GND..............................................................-0.3V to +7V

SHDN

to GND..............................................................-7V to +7V

SHDN

to IN .................................................................-7V to 0.3V

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

IN

+ 0.3V)

Continuous Power Dissipation (T

A

= +70°C)

SOT23-5 (derate 7.1mW/°C above +70°C).................571mW

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

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

θJA..................................................................................140°C/W

Storage Temperature Range.............................-65°C to +160°C

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

Ω

300

Shutdown Discharge
Resistance (MAX8874)

0.05

0 100

I

SHDN

SHDN Input Bias Current

V

0.4V

IL

SHDN Input Threshold

2.0V

IH

µV

RMS

220

Output Voltage Noise

350

%/mA

0.011 0.030

%/V-0.15 0 0.15∆V

LNR

Line Regulation

mV

55 120

Dropout Voltage (Note 5)

V2.5 6.5V

IN

Input Voltage (Note 2)

1.1

µA

73 150

I

Q

Ground Pin Current

3.05 3.15 3.25

V

OUT

Output Voltage

VV

SET

6.5V

OUT

Adjustable Output Voltage
Range (Note 3)

mA120Maximum Output Current

UNITSMIN TYP MAXSYMBOLPARAMETER

V

SHDN

= V

IN

C

OUT

= 100µF

I

OUT

= 0mA

VIN= 2.5V to 6.5V, SET tied to OUT,
I

OUT

= 1mA

0mA ≤ I

OUT

≤ 50mA,

SET = GND

I

OUT

= 50mA

CONDITIONS

mA280I

LIM

Current Limit (Note 4)

V

MAX887_T

10Hz to 1MHz

I

OUT

= 1mA

SET = GND

C

OUT

= 1µF

MAX887_S 2.75 2.84 2.93

I

OUT

= 50mA 82

0.02

µA

0.0001 1

I

QSHDN

Shutdown Supply Current V

OUT

= 0V

TA= T

MAX

TA= +25°C

TA= T

MAX

TA= +25°C

nA

MAX887_R 2.70 2.80 2.88

I

OUT

= 0mA to 50mA

0.006

∆V

LDR

Load Regulation

SET tied to OUT

SET = GND

SHUTDOWN

MAX8873T/S/R, MAX8874T/S/R

Low-Dropout, 120mA Linear Regulators

_______________________________________________________________________________________

3

__________________________________________Typical Operating Characteristics

(V

IN

= +3.6V, CIN= 1µF, C

OUT

= 1µF, MAX887_T, TA= +25°C, unless otherwise noted.)

UNITSMIN TYP MAXSYMBOLPARAMETER CONDITIONS

ELECTRICAL CHARACTERISTICS (continued)

(VIN= +3.6V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

Note 1: Limits are 100% production tested at T

A

= +25°C. Limits over the operating temperature range are guaranteed through cor-

relation using Statistical Quality Control (SQC) methods.

Note 2: Guaranteed by line-regulation test.
Note 3: Adjustable mode only.
Note 4: For design purposes, the current limit should be considered 120mA minimum to 420mA maximum.
Note 5: The dropout voltage is defined as (V

IN

- V

OUT

) when V

OUT

is 100mV below the value of V

OUT

for VIN= V

OUT

+ 2V.

T

SHDN

°CThermal Shutdown Temperature 170

∆T

SHDN

°CThermal Shutdown Hysteresis 20

SET Input Leakage Current
(Note 3)

nA

0.015 2.5

I

SET

V

SET

= 1.3V

SET Reference Voltage (Note 3) V

1.225 1.25 1.275

V

SET

V

IN

= 2.5V to 6.5V,

I

OUT

= 1mA

SET INPUT

THERMAL PROTECTION

TA= +25°C

TA= +25°C
TA= T

MIN

to T

MAX

TA= T

MAX

0.5

1.215 1.25 1.285

3.00

3.05

3.10

3.15

3.20

3.25

3.30

0 20 60 100

120

OUTPUT VOLTAGE

vs. LOAD CURRENT

MAX8873/74-01

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

40 80

100

50

0 20 60

120

100

SUPPLY CURRENT

vs. LOAD CURRENT

60

90

MAX8873/74-02

LOAD CURRENT (mA)

SUPPLY CURRENT (µA)

40

80

80

70

95

55

85

75

65

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1 2 4 6 7

OUTPUT VOLTAGE

vs. INPUT VOLTAGE

MAX8873/74-03

INPUT VOLTAGE (V)

OUTPUT VOLTAGE (V)

3 5

NO LOAD

MAX8873T/S/R, MAX8874T/S/R

Low-Dropout, 120mA Linear Regulators

4 _______________________________________________________________________________________

____________________________Typical Operating Characteristics (continued)

(VIN= +3.6V, CIN= 1µF, C

OUT

= 1µF, MAX887_T, TA= +25°C, unless otherwise noted.)

1 10

MAX8873/74-08

FREQUENCY (kHz)

PSRR (dB)

70

60

50

40

30

20

10

0

100 1000

0.10.01

V

OUT

= 3.15V

R

L

= 100Ω

C

OUT

= 10µF

C

OUT

= 1µF

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

10

0.01

0.1 10 1001 1000

OUTPUT SPECTRAL NOISE DENSITY

vs. FREQUENCY

0.10

MAX8873/74-8A

FREQUENCY (kHz)

OUTPUT SPECTRAL NOISE DENSITY (µV/√Hz)

1

RL = 50Ω

C

OUT

= 1µF

C

OUT

= 100µF

1000

0.01
0 60 8020 40 100

120

REGION OF STABLE C

OUT

ESR

vs. LOAD CURRENT

0.1

MAX8873/74-8B

LOAD CURRENT (mA)

C

OUT

ESR (Ω)

1

10

100

INTERNAL FEEDBACK

STABLE REGION

C

OUT

= 1µF

EXTERNAL FEEDBACK

0

20

40

60

80

100

120

140

160

0 20 60 100

120

DROPOUT VOLTAGE
vs. LOAD CURRENT

MAX8873/74-07

LOAD CURRENT (mA)

DROPOUT VOLTAGE (mV)

40 80

TA = +85°C

TA = +25°C

TA = -40°C

I

LOAD

= 50mA, V

OUT

IS AC COUPLED

OUTPUT NOISE DC TO 1MHz

V

OUT

1ms/div

0

10

20

30

40

60
50

70

80

90

100

0 1 2 5 7

SUPPLY CURRENT

vs. INPUT VOLTAGE

MAX8873/74-04

INPUT VOLTAGE (V)

3 4 6

SUPPLY CURRENT (µA)

I

LOAD

= 0mA

I

LOAD

= 50mA

3.00

3.05

3.10

3.15

3.20

3.25

3.30

0 20-20 60 100

OUTPUT VOLTAGE

vs. TEMPERATURE

MAX8873/74-05

TEMPERATURE (°C)

OUTPUT VOLTAGE (V)

40-40 80

I

LOAD

= 50mA

0

10

20

30

40

50

60

70

80

90

100

100806040200-20-40

SUPPLY CURRENT

vs. TEMPERATURE

MAX8863/4-06

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

I

LOAD

= 50mA

MAX8873T/S/R, MAX8874T/S/R

Low-Dropout, 120mA Linear Regulators

_______________________________________________________________________________________ 5

I

LOAD

= 0mA to 50mA, CIN = 10µF, V

OUT

IS AC COUPLED

LOAD-TRANSIENT RESPONSE

3.16V

V

OUT

3.15V

3.14V

I

LOAD

50mA

0mA

10µs/div

VIN = V

OUT

+ 0.2V, I

LOAD

= 0mA to 50mA, CIN = 10µF,

V

OUT

IS AC COUPLED

LOAD-TRANSIENT RESPONSE

I

LOAD

3.16V

V

OUT

3.15V

3.14V

50mA

0mA

10µs/div

____________________________Typical Operating Characteristics (continued)

(VIN= +3.6V, CIN= 1µF, C

OUT

= 1µF, MAX887_T, TA= +25°C, unless otherwise noted.)

I

LOAD

= 50mA, V

OUT

IS AC COUPLED

LINE-TRANSIENT RESPONSE

3.16V

V

OUT

3.15V

3.14V

4.6V

3.6V

V

IN

50µs/div

VIN = V

OUT

+ 0.1V, I

LOAD

= 0mA to 50mA, CIN = 10µF,

V

OUT

IS AC COUPLED

LOAD-TRANSIENT RESPONSE

0mA

50mA

10µs/div

3.16V

V

OUT

3.15V

3.14V

I

LOAD

NO LOAD

MAX8874 SHUTDOWN (NO LOAD)

0V

V

SHDN

4V

V

OUT

0V

2V

2V

500µs/div

I

LOAD

= 50mA

MAX8874 SHUTDOWN

0V

V

SHDN

V

OUT

4V
2V

0V

2V

200µs/div

MAX8873T/S/R, MAX8874T/S/R

Low-Dropout, 120mA Linear Regulators

6 _______________________________________________________________________________________

_______________Detailed Description

The MAX8873/MAX8874 are low-dropout, low-quiescent­current linear regulators designed primarily for battery­powered applications. They supply an adjustable 1.25V to

6.5V output or a preselected 2.80V (MAX887_R), 2.84V
(MAX887_S), or 3.15V (MAX887_T) output for load currents
up to 120mA. These devices consist of a 1.25V reference,
error amplifier, MOSFET driver, P-channel pass transistor,
dual-mode comparator, and internal feedback voltage
divider (Figure 1).

The 1.25V bandgap reference is connected to the error
amplifier’s inverting input. The error amplifier compares this
reference with the selected feedback voltage and amplifies
the difference. The MOSFET driver reads the error signal

and applies the appropriate drive to the P-channel pass
transistor. If the feedback voltage is lower than the refer­ence, the pass-transistor gate is pulled lower, allowing more
current to pass and increasing the output voltage. If the
feedback voltage is too high, the pass-transistor gate is
pulled up, allowing less current to pass to the output.

The output voltage is fed back through either an internal
resistor voltage divider connected to the OUT pin, or an
external resistor network connected to the SET pin. The
dual-mode comparator examines the SET voltage and
selects the feedback path. If SET is below 60mV, internal
feedback is used and the output voltage is regulated to the
preset output voltage. Additional blocks include a current
limiter, reverse battery protection, thermal sensor, and shut­down logic.

SHUTDOWN

LOGIC

ERROR

AMP

1.25V
REF

P

N

*

SET

OUT

DUAL-MODE
COMPARATOR

60mV

* AUTO-DISCHARGE, MAX8874 ONLY

GND

IN

SHDN

MAX8873

MAX8874

MOS DRIVER

WITH I

LIMIT

THERMAL

SENSOR

REVERSE
BATTERY

PROTECTION

______________________________________________________________Pin Description

Figure 1. Functional Diagram

OUT

GND2

Ground. This pin also functions as a heatsink. Solder to large pads or the circuit board ground plane to max­imize thermal dissipation.

3

Active-Low Shutdown Input. A logic low reduces the supply current to 0.1nA. On the MAX8874, a logic low
also causes the output voltage to discharge to GND. Connect to IN for normal operation.

SET4

Feedback Input for Setting the Output Voltage. Connect to GND to set the output voltage to the preset 2.80V
(MAX887_R), 2.84V (MAX887_S), or 3.15V (MAX887_T). Connect to an external resistor divider for
adjustable-output operation. DO NOT LEAVE THIS PIN UNCONNECTED.

5

Regulator Output. Fixed or adjustable from 1.25V to 6.5V. Sources up to 120mA. Bypass with a 1µF, <0.2Ω
typical ESR capacitor to GND.

SHDN

Regulator Input. Supply voltage can range from 2.5V to 6.5V. Bypass with 1µF to GND (see

Capacitor

Selection and Regulator Stability

).

IN1

PIN FUNCTIONNAME

MAX8873T/S/R, MAX8874T/S/R

Low-Dropout, 120mA Linear Regulators

_______________________________________________________________________________________ 7

Internal P-Channel Pass Transistor

The MAX8873/MAX8874 feature a 1.1Ω typical P-chan­nel MOSFET pass transistor. This provides several
advantages over similar designs using PNP pass tran­sistors, including longer battery life.

The P-channel MOSFET requires no base drive current,
which reduces quiescent current considerably. PNP­based regulators waste considerable amounts of cur­rent in dropout when the pass transistor saturates. They
also use high base-drive currents under large loads.
The MAX8873/MAX8874 do not suffer from these prob­lems, and consume only 82µA of quiescent current,
whether in dropout, light load, or heavy load applica­tions (see

Typical Operating Characteristics

).

Output Voltage Selection

The MAX8873/MAX8874 feature Dual Mode operation:
they operate in either a preset voltage mode or an
adjustable mode.

In preset voltage mode, internal, trimmed feedback
resistors set the MAX887_R output to 2.80V, the
MAX887_S output to 2.84V, and the MAX887_T output to

3.15V. Select this mode by connecting SET to ground.
In adjustable mode, select an output between 1.25V

and 6.5V using two external resistors connected as a
voltage divider to SET (Figure 2). The output voltage is
set by the following equation:

V

OUT

= V

SET

(1 + R1 / R2)

where V

SET

= 1.25V. To simplify resistor selection:

Choose R2 = 100kΩ to optimize power consumption,
accuracy, and high-frequency power-supply rejection.
The total current through the external resistive feedback
and load resistors should not be less than 10µA. Since
the V

SET

tolerance is typically less than ±25mV, the out­put can be set using fixed resistors instead of trim pots.
Connect a 10pF to 25pF capacitor across R1 to com­pensate for layout-induced parasitic capacitances.

In preset voltage mode, impedances between SET and
ground should be less than 100kΩ. Otherwise, spurious
conditions could cause the voltage at SET to exceed
the 60mV dual-mode threshold.

Shutdown

A low input on the SHDN pin shuts down the
MAX8873/MAX8874. In shutdown mode, the pass tran­sistor, control circuit, reference, and all biases are
turned off, reducing the supply current to typically

0.1nA. Connect SHDN to IN for normal operation. The
MAX8874 output voltage is actively discharged to
ground when the part is placed in shutdown (see

Typical Operating Characteristics

).

Current Limit

The MAX8873/MAX8874 include a current limiter that
monitors and controls the pass transistor’s gate volt­age, estimating the output current and limiting it to
about 280mA. For design purposes, the current limit
should be considered 120mA to 420mA. The output
can be shorted to ground for an indefinite time period
without damaging the part.

Thermal Overload Protection

Thermal overload protection limits total power dissipa­tion in the MAX8873/MAX8874. When the junction tem­perature exceeds TJ= +170°C, the thermal sensor
sends a signal to the shutdown logic, turning off the
pass transistor and allowing the IC to cool. The thermal
sensor turns the pass transistor on again after the IC’s
junction temperature typically cools by 20°C, resulting
in a pulsed output during continuous thermal overload
conditions.

Thermal overload protection is designed to protect the
MAX8873/MAX8874 in the event of fault conditions.
Stressing the device with high load currents and high
input-output differential voltages (which result in die tem­peratures above +125°C) may cause a momentary over­shoot (2% to 8% for 200ms) when the load is completely
removed. This can be remedied by raising the minimum
load current from 0µA (+125°C) to 100µA (+150°C). For
continuous operation, do not exceed the absolute maxi­mum junction temperature rating of TJ= +150°C.

MAX8873
MAX8874

OUT

SET

GND

IN

1

5

4

2

3

SHDN

C

OUT

1µF

C

IN

1µF

BATTERY

OUTPUT
VOLTAGE

R1 20pF

R2

R

L

Figure 2. Adjustable Output Using External Feedback
Resistors

R1 R2

V

V

1

OUT

SET

= −













MAX8873T/S/R, MAX8874T/S/R

Low-Dropout, 120mA Linear Regulators

Operating Region and Power Dissipation

Maximum power dissipation of the MAX8873/MAX8874
depends on the thermal resistance of the case and cir­cuit board, the temperature difference between the die
junction and ambient air, and the rate of air flow. The
power dissipation across the device is P = I

OUT(VIN

-

V

OUT

). The resulting maximum power dissipation is:

P

MAX

= (TJ- TA) / θ

JA

where (TJ- TA) is the temperature difference between
the MAX8873/MAX8874 die junction and the surround­ing air, and θJAis the thermal resistance of the chosen
package to the surrounding air.

The GND pin of the MAX8873/MAX8874 performs the
dual function of providing an electrical connection to
ground and channeling heat away. Connect the GND
pin to ground using a large pad or ground plane.

Reverse Battery Protection

The MAX8873/MAX8874 have a unique protection
scheme that limits the reverse supply current to less
than 1mA when either VINor V

SHDN

falls below ground.
The circuitry monitors the polarity of these two pins, dis­connecting the internal circuitry and parasitic diodes
when the battery is reversed. This feature prevents the
device from overheating and damaging the battery.

VIN> 5.5V Minimum Load Current

When operating the MAX8873/MAX8874 with an input
voltage above 5.5V, a minimum load current of 20µA is
required to maintain regulation in preset voltage mode.
When setting the output with external resistors, the min­imum current through the external feedback resistors
and load must be 30µA.

__________Applications Information

Capacitor Selection and

Regulator Stability

Normally, use a 1µF capacitor on the input and a 1µF
capacitor on the output of the MAX8873/MAX8874.
Larger input capacitor values and lower ESR provide
better supply-noise rejection and transient response. A
higher-value input capacitor (10µF) may be necessary
if large, fast transients are anticipated and the device is
located several inches from the power source. Improve
load-transient response, stability, and power-supply
rejection by using large output capacitors. For stable
operation over the full temperature range, with load cur­rents up to 120mA, a minimum of 1µF is recommended.

Noise

The MAX8873/MAX8874 exhibit 350µV

RMS

noise during
normal operation. When using the MAX8873/MAX8874
in applications that include analog-to-digital converters
(ADCs) of greater than 12 bits, consider the ADC’s
power-supply rejection specifications (see the Output
Noise DC to 1MHz photo in the

Typical Operating

Characteristics

). For devices with lower output noise,

refer to the MAX8877/MAX8878.

Power-Supply Rejection and Operation

from Sources Other than Batteries

The MAX8873/MAX8874 are designed to deliver low
dropout voltages and low quiescent currents in battery­powered systems. Power-supply rejection is 62dB at
low frequencies and rolls off above 300Hz. As the fre­quency increases above 20kHz, the output capacitor is
the major contributor to the rejection of power-supply
noise (see the Power-Supply Rejection Ratio vs.
Frequency graph in the

Typical Operating

Characteristics

).

When operating from sources other than batteries,
improve supply-noise rejection and transient response
by increasing the values of the input and output capac­itors, and by using passive filtering techniques (see the
supply and load-transient responses in the

Typical

Operating Characteristics

).

Load-Transient Considerations

The MAX8873/MAX8874 load-transient response
graphs (see

Typical Operating Characteristics

) show
two components of the output response: a DC shift of
the output voltage due to the different load currents
and the transient response. Typical overshoot for step
changes in the load current from 0mA to 50mA is
14mV. Increasing the output capacitor’s value and
decreasing its ESR attenuates transient spikes.

Input-Output (Dropout) Voltage

A regulator’s minimum input-output voltage differential
(or dropout voltage) determines the lowest usable sup­ply voltage. In battery-powered systems, this will deter­mine the useful end-of-life battery voltage. Because the
MAX8873/MAX8874 use a P-channel MOSFET pass
transistor, their dropout voltage is a function of R

DS(ON)

multiplied by the load current (see

Electrical

Characteristics

).

___________________Chip Information

TRANSISTOR COUNT: 148

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

8

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