19-4662; Rev 0; 6/09
Low-Noise, High PSRR,
Low-Dropout, 120mA Linear Regulator
General Description
The MAX8940 low-noise, low-dropout (LDO) linear reg-
ulator is designed to deliver up to 120mA continuous
output current. This regulator achieves a low 120mV
dropout for 120mA load current. The MAX8940 uses an
advanced architecture to achieve low output voltage
noise of 25µV
RMS
and PSRR of 45dB at 100kHz.
The MAX8940 is preset to either 2.8V or 3.0V. Designed
with a p-channel MOSFET series pass transistor, the
MAX8940 maintain very low ground current (40µA).
The regulator is designed and optimized to work with low-
value, low-cost ceramic capacitors. The MAX8940
requires only 1µF (typ) of output capacitance for stability
with any load. When disabled, current consumption drops
to below 1µA.
Package is a 5-pin SC70.
Features
♦
Space-Saving SC70
♦
25µV
RMS
Output Noise at 100Hz to 100kHz
Bandwidth
♦
♦
♦
♦
♦
65dB PSRR at 10kHz
120mV Dropout at 120mA Load
Stable with 1µF Ceramic Capacitor for Any Load
Guaranteed 120mA Output
Output Voltages: 2.8V or 3V
MAX8940
♦
Low 40µA Ground Current
♦
Excellent Load/Line Transient
♦
Overcurrent and Thermal Protection
Applications
Cellular and Cordless Phones
PDA and Palmtop Computers
Base Stations
Bluetooth Portable Radios and Accessories
Wireless LANs
Digital Cameras
Personal Stereos
Portable and Battery-Powered Equipment
PART*
MAX8940EXKxy-T
MAX8940EXKxy+T
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
5 SC70
5 SC70
*xy
is the output voltage code (see Output Voltage Selector
Guide).
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Output Voltage Selector Guide
PART
MAX8940EXK28-T
MAX8940EXK30-T
V
OUT
(V)
2.8
3
TOP MARK
AUE
AUD
Pin Configuration
TOP VIEW
IN 1
5 OUT
Typical Operating Circuit
INPUT
2V TO 6V
C
IN
= 1µF
ON
OFF
IN
OUT
PRESET OUTPUT
2.8V OR 3.0V
GND 2
MAX8940
4 BP
MAX8940
SHDN
GND
BP
C
BP
= 10nF
C
OUT
= 1µF
SHDN 3
SC70
________________________________________________________________
Maxim Integrated Products
1
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.
Low-Noise, High PSRR,
Low-Dropout, 120mA Linear Regulator
MAX8940
ABSOLUTE MAXIMUM RATINGS
IN to GND .................................................................-0.3V to +7V
Output Short-Circuit Duration ............................................Infinite
OUT,
SHDN
to GND ......................................-0.3V to (IN + 0.3V)
FB, BP, N.C. to GND..................................-0.3V to (OUT + 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SC70 (derate 3.1mW/°C above +70°C) ..............0.247W
θ
JA
5-Pin SC70 ................................................................324°C/W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°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.
ELECTRICAL CHARACTERISTICS
(V
IN
= V
OUT
+ 0.5V, T
A
= -40°C to +85°C, unless otherwise noted. C
IN
= 1µF, C
OUT
= 1µF, C
BP
= 10nF. Typical values are at +25°C;
the MAX8940 is tested with 2.45V output, unless otherwise noted.) (Note 1)
PARAMETER
Input Voltage Range
Output Voltage Accuracy
Maximum Output Current
Current Limit
I
OUT
I
LIM
OUT = 90% of nominal value
V
OUT
= 3V, I
OUT
= 80mA
Dropout Voltage (Note 2)
V
OUT
= 3V, I
OUT
= 120mA
V
OUT
= 2.8V, I
OUT
= 80mA
V
OUT
= 2.8V, I
OUT
= 120mA
Ground Current
Line Regulation
Load Regulation
Shutdown Supply Current
Ripple Rejection
I
Q
V
LNR
V
LDR
I
SHDN
PSRR
I
OUT
= 0.05mA
V
IN
= V
OUT
(nom) - 0.1V, I
OUT
= 0mA
V
IN
= (V
OUT
+ 0.5V) to 6V, I
OUT
= 0.1mA
I
OUT
= 1mA to 80mA
SHDN
= 0V
f = 10kHz, I
OUT
= 10mA
f = 100kHz, I
OUT
= 10mA
T
A
= +25°C
T
A
= +85°C
SYMBOL
V
IN
I
OUT
= 1mA, T
A
= +25°C
I
OUT
= 100µA to 80mA, T
A
= +25°C
I
OUT
= 100µA to 80mA
CONDITIONS
MIN
2.8
-1
-2
-3
120
130
200
80
120
90
135
40
220
0.001
0.003
0.003
0.05
65
45
1
90
500
µA
%/V
%/mA
µA
dB
200
300
170
mV
TYP
MAX
6
+1
+2
+3
mA
mA
%
UNITS
V
2
_______________________________________________________________________________________
Low-Noise, High PSRR,
Low-Dropout, 120mA Linear Regulator
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
OUT
+ 0.5V, T
A
= -40°C to +85°C, unless otherwise noted. C
IN
= 1µF, C
OUT
= 1µF, C
BP
= 10nF. Typical values are at +25°C;
the MAX8940 is tested with 2.45V output, unless otherwise noted.) (Note 1)
PARAMETER
Output Noise Voltage
(RMS)
Shutdown Exit Delay
SHDN
Logic Low Level
SHDN
Logic High Level
SHDN
Input Bias Current
Thermal Shutdown
Thermal-Shutdown
Hysteresis
SYMBOL
CONDITIONS
f = 100Hz to 100kHz, I
LOAD
= 10mA
f = 100Hz to 100kHz, I
LOAD
= 80mA
R
LOAD
= 50Ω (Note 3)
V
IN
= 2.8V to 6V
V
IN
= 2.8V to 6V
V
IN
= 6V,
SHDN
= 0V or
6V
T
A
= +25°C
T
A
= +85°C
0.01
160
10
1.5
MIN
TYP
25
13
300
0.4
MAX
UNITS
µV
µs
V
V
µA
°C
°C
MAX8940
Note 1:
Limits are 100% tested at +25°C. Limits over operating temperature range are guaranteed by design.
Note 2:
Dropout is defined as V
IN
- V
OUT
when V
OUT
is 100mV below the value of V
OUT
for V
IN
= V
OUT
+ 0.5V.
Note 3:
Time needed for V
OUT
to reach 90% of final value.
Typical Operating Characteristics
(V
IN
= V
OUT
+ 0.5V, C
IN
= 1µF, C
OUT
= 1µF, C
BP
= 10nF, T
A
= +25°C, unless otherwise noted.)
OUTPUT VOLTAGE ACCURACY
vs. LOAD CURRENT
MAX8940 toc01
MAX8940 toc02
OUTPUT VOLTAGE vs. INPUT VOLTAGE
3.0
2.5
OUTPUT VOLTAGE (V)
I
OUT
= 0mA
% DEVIATION (%)
2.0
1.5
1.0
0.5
0.0
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
I
OUT
= 120mA
0.2
0
-0.2
-0.4
-0.6
0
0.6
0.4
OUTPUT VOLTAGE ACCURACY
vs. TEMPERATURE
0.8
0.6
% DEVIATION (%)
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
IOUT = 1mA
MAX8940 toc03
1.0
20
40
60
80
100
120
-40
-15
10
35
60
85
LOAD CURRENT (mA)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
Low-Noise, High PSRR,
Low-Dropout, 120mA Linear Regulator
MAX8940
Typical Operating Characteristics (continued)
(V
IN
= V
OUT
+ 0.5V, C
IN
= 1µF, C
OUT
= 1µF, C
BP
= 10nF, T
A
= +25°C, unless otherwise noted.)
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX8940 toc04
GROUND PIN CURRENT vs. INPUT VOLTAGE
MAX8940 toc05
GROUND PIN CURRENT vs. LOAD CURRENT
V
IN
= 5.5V
MAX8940 toc 06
150
T
A
= +85°C
DROPOUT VOLTAGE (mV)
120
T
A
= +25°C
90
350
I
OUT
= 120mA
300
GROUND PIN CURRENT (µA)
250
200
150
100
50
I
OUT
= 0mA
240
200
160
V
IN
= 3.8V
120
80
40
0
60
T
A
= -40°C
30
0
0
20
40
60
80
100
120
LOAD CURRENT (mA)
0
0
1
2
3
4
5
INPUT VOLTAGE (V)
GROUND PIN CURRENT (µA)
0
20
40
60
80
100
120
LOAD CURRENT (mA)
GROUND PIN CURRENT vs. TEMPERATURE
MAX8940 toc07
PSRR vs. FREQUENCY
80
70
60
PSRR (dB)
50
40
30
MAX8940 toc08
50
90
GROUND PIN CURRENT (µA)
45
40
35
20
10
I
LOAD
= 10mA
C
BP
= 10nF
0.01
0.1
1
10
100
1000
30
-40
-15
10
35
60
85
TEMPERATURE (°C)
0
FREQUENCY (kHz)
OUTPUT NOISE
MAX8940 toc09
OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
1.E+04
OUTPUT NOISE DENSITY (nV/√Hz)
MAX8940 toc10
V
IN
= 3.8V
I
LOAD
= 10mA
V
NOISE
= 25µV
RMS
1.E+03
1.E+02
20µV/div
400µs/div
1.E+01
0.01
0.1
1
10
100
1000
FREQUENCY (kHz)
4
_______________________________________________________________________________________
Low-Noise, High PSRR,
Low-Dropout, 120mA Linear Regulator
Typical Operating Characteristics (continued)
(V
IN
= V
OUT
+ 0.5V, C
IN
= 1µF, C
OUT
= 1µF, C
BP
= 10nF, T
A
= +25°C, unless otherwise noted.)
OUTPUT NOISE vs. BP CAPACITANCE
MAX8940 toc11
MAX8940
LOAD TRANSIENT RESPONSE
MAX8940 toc12
LOAD TRANSIENT
RESPONSE NEAR DROPOUT
MAX8940 toc13
25
20
OUTPUT NOISE (µV)
V
IN
= 3.5V
I
LOAD
= 0 TO 50mA
V
IN
= 3.1V
I
LOAD
= 0 TO 50mA
V
OUT
= 3V
15
10
V
OUT
10mV/div
5
V
OUT
10mV/div
0
1
10
BP CAPACITANCE (nF)
100
1ms/div
1ms/div
LINE TRANSIENT RESPONSE
MAX8940 toc14
EXITING SHUTDOWN WAVEFORM
SHUTDOWN VOLTAGE
ENTERING SHUTDOWN DELAY
MAX8940 toc16
MAX8940 toc15
V
IN
= 3.5V TO 4V
V
OUT
= 2.8V
R
LOAD
= 47Ω
SHUTDOWN
VOLTAGE
C
BP
= 0.01µF
V
OUT
= 2.8V
OUTPUT VOLTAGE
2V/div
V
OUT
2mV/div
200µs/div
20µs/div
OUTPUT VOLTAGE
2V/div
40µs/div
SHUTDOWN EXIT DELAY
V
OUT
= 3V
C
BP
= 100nF
REGION OF STABLE C
OUT
ESR
vs. LOAD CURRENT
MAX8940 toc18
MAX8940 toc17
100
V
OUT
1V/div
C
OUT
ESR (Ω)
10
1
SHUTDOWN
VOLTAGE
0.1
STABLE REGION
0.01
20µs/div
0
20
40
60
80
100
120
LOAD CURRENT (mA)
_______________________________________________________________________________________
5
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