19-2599; Rev 0; 10/02
500mA, Low-Voltage Linear Regulator
in Tiny QFN
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.
o
Guaranteed 500mA Output Current
o
Output Down to 0.8V
o
Low 175mV Dropout at 500mA
o
±1.5% Output Voltage Accuracy
Preset at 1.5V
Adjustable from 0.8V to 4.5V
o
Power-OK Output
o
Low 210µA Ground Current
o
0.02µA Shutdown Current
o
Thermal-Overload Protection
o
Output Current Limit
o
Tiny 1.9W, 8-Pin 3mm x 3mm Thin QFN Package
Features
MAX1935
Ordering Information
Applications
Notebook Computers
Cellular and Cordless Telephones
PDAs
Palmtop Computers
Base Stations
USB Hubs
Docking Stations
PART
MAX1935ETA
MAX1935ETA15
PART
MAX1935ETA*
MAX1935ETA15*
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 Thin QFN
3mm x 3mm
8 Thin QFN
3mm x 3mm
*Contact
factory for preset output voltages.
Selector Guide
OUTPUT
VOLTAGE
Adjustable
1.5V
TOP MARK
ADB
ADB
Typical Operating Circuit
R
POK
100kΩ
POK
TO
µC
V
IN
2.25V TO 5.5V
C
IN
1µF
ON
SHDN
OFF
GND
OUT
C
OUT
10µF
V
OUT
0.8V TO 4.5V
Pin Configuration
TOP VIEW
R
1
IN
IN
POK
SHDN
1
2
3
4
8
OUT
OUT
SET
GND
MAX1935
IN
SET
MAX1935
7
6
5
R
2
THIN QFN
3mm x 3mm
________________________________________________________________
Maxim Integrated Products
1
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.
500mA, Low-Voltage Linear Regulator
in Tiny QFN
MAX1935
ABSOLUTE MAXIMUM RATINGS
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
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(SETPOINT)
+ 500mV or V
IN
= 2.25V whichever is greater, SET = GND,
SHDN
= IN,
T
A
= 0°C to +85°C,
unless otherwise
noted. Typical values are at T
A
= +25°C.)
PARAMETER
Input Voltage
Input Undervoltage Lockout
Output Voltage Accuracy
(Preset Mode)
Adjustable Output Voltage
T
A
= +25°C, I
OUT
= 100mA
SET Voltage Threshold
(Adjustable Mode)
Maximum Output Current
Short-Circuit Current Limit
SET Dual Mode
™
Threshold
SET Input Bias Current
Ground-Pin Current
I
SET
I
Q
V
SET
= 0.8V
I
OUT
= 1mA
I
OUT
= 500mA
V
OUT
= 2.25V
Dropout Voltage (Note 1)
Line Regulation
Load Regulation
Output Voltage Noise
SHUTDOWN
Shutdown Supply Current
SHDN
Input Threshold
SHDN
Input Bias Current
Startup Time
I
OFF
V
IH
V
IL
I
SHDN
t
START
SHDN
= GND or IN
C
OUT
= 10µF, time from
SHDN
high to POK high
10
40
SHDN
= GND, V
IN
= 5.5V
1.6
0.6
100
0.02
5
µA
V
nA
µs
∆V
LNR
∆V
LDR
I
OUT
= 500mA
V
OUT
= 2.8V
V
OUT
= 4V
V
IN
from (V
OUT
+ 100mV) to 5.5V, I
LOAD
= 5mA
I
OUT
= 1mA to 500mA
10Hz to 1MHz, C
OUT
= 10µF (ESR < 0.1Ω)
V
SET
T
A
= +25°C, I
OUT
= 1mA to 500mA
T
A
= 0°C to +85°C, I
OUT
= 1mA to 500mA,
V
IN
> V
OUT
+ 0.5V
V
OUT
= 0V
SYMBOL
V
IN
V
UVLO
Rising, 40mV hysteresis
T
A
= +25°C, I
OUT
= 100mA
V
OUT
T
A
= +25°C, I
OUT
= 1mA to 500mA
T
A
= 0°C to +85°C, I
OUT
= 1mA to 500mA,
V
IN
> V
OUT
+ 0.5V
CONDITIONS
MIN
2.25
1.85
-1.5
-2.5
-3
0.8
788
780
774
500
600
35
-100
210
575
259
201
147
0
15.5
300
400
350
275
0.125
35
%/V
ppm/mA
µV
RMS
mV
1400
80
2300
125
+100
600
800
2
TYP
MAX
5.50
2.15
+1.5
+2.5
+3
4.5
812
820
826
mA
RMS
mA
mV
nA
µA
mV
V
%
UNITS
V
V
I
OUT
I
LIM
Dual Mode is a trademark of Maxim Integrated Products, Inc.
2
_______________________________________________________________________________________
500mA, Low-Voltage Linear Regulator
in Tiny QFN
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
OUT(SETPOINT)
+ 500mV or V
IN
= 2.25V whichever is greater, SET = GND,
SHDN
= IN,
T
A
= 0°C to +85°C,
unless otherwise
noted. Typical values are at T
A
= +25°C.)
PARAMETER
POWER-OK
POK Output Low Voltage
Operating Voltage Range for
Valid POK Output
Output High Leakage Current
Threshold
THERMAL PROTECTION
Thermal-Shutdown Temperature
Thermal-Shutdown Hysteresis
T
SHDN
∆T
SHDN
170
20
°C
°C
V
OL
Sinking 2mA
Sinking 100µA
V
POK
= 5.5V
Rising edge, referred to V
OUT(NOMINAL)
90
93
1.0
5
50
5.5
100
96
mV
V
nA
%
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1935
ELECTRICAL CHARACTERISTICS
(V
IN
= V
OUT(SETPOINT)
+ 500mV or V
IN
= 2.25V whichever is greater, SET = GND,
SHDN
= IN,
T
A
= -40°C to +85°C,
unless otherwise
noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Input Voltage
Input Undervoltage Lockout
Output Voltage Accuracy
(Preset Mode)
Adjustable Output Voltage
SET Voltage Threshold
(Adjustable Mode)
Maximum Output Current
Short-Circuit Current Limit
SET Dual Mode Threshold
SET Input Bias Current
Ground-Pin Current
SHUTDOWN
Shutdown Supply Current
SHDN
Input Threshold
SHDN
Input Bias Current
I
OFF
V
IH
V
IL
I
SHDN
SHDN
= GND, V
IN
= 5.5V
2.5V < V
IN
< 5.5V
2.5V < V
IN
< 5.5V
SHDN
= GND or IN
1.6
0.6
100
5
µA
V
nA
I
SET
I
Q
V
SET
= 0.8V
I
OUT
= 1mA
V
SET
I
OUT
I
LIM
V
OUT
= 0V
I
OUT
= 1mA to 500mA
SYMBOL
V
IN
V
UVLO
V
OUT
Rising, 40mV hysteresis
I
OUT
= 1mA to 500mA
CONDITIONS
MIN
2.25
1.85
-4
0.8
766
500
600
35
-100
2500
125
+100
400
TYP
MAX
5.50
2.15
+4
4.5
834
UNITS
V
V
%
V
mV
mA
RMS
mA
mV
nA
µA
_______________________________________________________________________________________
3
500mA, Low-Voltage Linear Regulator
in Tiny QFN
MAX1935
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
OUT(SETPOINT)
+ 500mV or V
IN
= 2.25V whichever is greater, SET = GND,
SHDN
= IN,
T
A
= -40°C to +85°C,
unless otherwise
noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
POWER-OK
POK Output Low Voltage
Operating Voltage Range for
Valid POK Output
Output High Leakage Current
Threshold
V
OL
Sinking 2mA
Sinking 100µA
V
POK
= 5.5V
Rising edge, referred to V
OUT(NOMINAL)
89
1.0
50
5.5
100
97
mV
V
nA
%
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
Dropout voltage is defined as V
IN
- V
OUT
, when V
OUT
is 100mV below the value of V
OUT
and when V
IN
= 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, V
IN
= V
OUT
+ 500mV,
SHDN
= IN, C
IN
= 1µF, C
OUT
= 10µF, T
A
= +25°C, unless otherwise noted.)
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX1935 toc01
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX1935 toc02
OUTPUT VOLTAGE vs. TEMPERATURE
V
IN
= V
OUT
+ 500mV
I
OUT
= 0
MAX1935 toc03
3.5
I
OUT
= 0mA
3.0
OUTPUT VOLTAGE (V)
2.5
2.0
1.5
1.0
0.5
0
I
OUT
= 500mA
3.32
3.31
OUTPUT VOLTAGE (V)
3.30
3.29
3.28
3.27
3.26
3.25
3.34
3.33
OUTPUT VOLTAGE (V)
3.32
3.31
3.30
3.29
3.28
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
INPUT VOLTAGE (V)
0
100 200 300 400 500 600 700 800
LOAD CURRENT (mA)
-40
-15
10
35
60
85
TEMPERATURE (°C)
DROPOUT VOLTAGE vs. LOAD CURRENT
350
DROPOUT VOLTAGE (mV)
300
250
200
150
100
50
0
0
100 200 300 400 500 600 700 800
LOAD CURRENT (mA)
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
MAX1935 toc04
DROPOUT VOLTAGE
vs. OUTPUT VOLTAGE
0.28
DROPOUT VOLTAGE (V)
0.26
0.24
0.22
0.20
0.18
0.16
0.14
2.0
2.5
3.0
3.5
4.0
4.5
OUTPUT VOLTAGE (V)
600
550
500
450
400
350
300
250
200
150
100
50
0
2.0
2.5
MAX1935 toc05
GROUND-PIN CURRENT
vs. INPUT VOLTAGE
MAX1935 toc06
400
GROUND-PIN CURRENT (µA)
I
OUT
= 500mA
I
OUT
= 0mA
3.0
3.5
4.0
4.5
5.0
5.5
6.0
INPUT VOLTAGE (V)
4
_______________________________________________________________________________________
500mA, Low-Voltage Linear Regulator
in Tiny QFN
MAX1935
Typical Operating Characteristics (continued)
(V
OUT
= 3.3V, V
IN
= V
OUT
+ 500mV,
SHDN
= IN, C
IN
= 1µF, C
OUT
= 10µF, T
A
= +25°C, unless otherwise noted.)
GROUND-PIN CURRENT
vs. LOAD CURRENT
MAX1935 toc07
GROUND-PIN CURRENT
vs. TEMPERATURE
V
IN
= V
OUT
+ 500mV
I
OUT
= 0
MAX1935 toc08
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX1935 toc09
500
450
GROUND-PIN CURRENT (µA)
400
350
300
250
200
150
V
IN
= 5.5V
V
IN
= 3.8V
200
-60
-50
-40
GROUND-PIN CURRENT (µA)
190
180
PSRR (dB)
-30
-20
170
160
-10
0
-40
-15
10
35
60
85
TEMPERATURE (°C)
150
C
OUT
= 10µF
I
OUT
= 50mA
0.01
0.1
1
10
100
1000
FREQUENCY (kHz)
100
0
100 200 300 400 500 600 700 800
LOAD CURRENT (mA)
OUTPUT SPECTRAL NOISE DENSITY
vs. FREQUENCY
OUTPUT SPECTRAL NOISE DENSITY (µV/
√
Hz)
C
OUT
= 10µF
I
OUT
= 50mA
MAX1935 toc10
OUTPUT NOISE DC TO 1MHz
MAX1935 toc11
10
1
0.1
V
OUT
1mV/div
0.01
V
OUT
= 3.3V
R
OUT
= 66Ω (50mA)
0.1
1
10
FREQUENCY (kHz)
100
1000
20ms/div
0.001
REGION OF STABLE C
OUT
ESR
vs. LOAD CURRENT
MAX1935 toc12
LOAD-TRANSIENT RESPONSE
MAX1935 toc13
100
REGION OF C
OUT
ESR
10
C
OUT
= 10µF
1
STABLE REGION
0.1
V
IN
= V
OUT
+ 500mV
C
IN
= 10µF
R
OUT
= 660Ω TO 6.6Ω (5mA TO 500mA)
0
100 200 300 400 500 600 700 800
FREQUENCY (kHz)
10µs/div
I
OUT
200mA/div
V
OUT
20mV/div
0.01
_______________________________________________________________________________________
5
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