General Description
The MAX1819 low-dropout linear regulator operates from
a 2.5V to 5.5V supply and delivers a guaranteed 500mA
load current with low 120mV dropout. The high-accuracy
(±1%) output voltage is preset at an internally trimmed
voltage (see the Selector Guide) or can be adjusted from
1.25V to 5V with an external resistive-divider.
An internal PMOS pass transistor allows the low 125µA
supply current to remain independent of load, making
this device ideal for portable battery-operated equip-
ment such as personal digital assistants (PDAs), cellu-
lar phones, cordless phones, base stations, and
notebook computers.
Other features include an active-low, open-drain reset
output that indicates when the output is out of regula-
tion, a 0.1µA shutdown, short-circuit protection, and
thermal shutdown protection. The device is available in
a miniature 6-pin UCSP™ package.
Applications
Notebook Computers
Cellular and Cordless Telephones
Personal Digital Assistants (PDAs)
Palmtop Computers
Base Stations
USB Hubs
Docking Stations
Features
♦Guaranteed 500mA Output Current
♦Low 90mV Dropout at 500mA
♦±1% Initial Output Accuracy
♦Preset Output at 1.5V, 1.8V, 2V, 2.5V, 3.3V, 5V
♦Adjustable Output from 1.25V to 5V
♦Power-OK Output
♦Low 125µA Ground Current
♦0.1µA Shutdown Current
♦Thermal Overload Protection
♦Output Current Limit
♦Tiny 840mW 6-Pin UCSP Package
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
________________________________________________________________ Maxim Integrated Products 1
19-2072; Rev 0; 1/02
Ordering Information
*Insert the desired two-digit suffix (see Selector Guide) into the
blanks to complete the part number.
PART
TEMP RANGE
PIN-PACKAGE
MAX1819EBL_ _ -T*
-40°C to +85°C
6 UCSP
PART AND
SUFFIX VOUT UCSP MARK
MAX1819EBL 15 1.5V or Adj AAH
MAX1819EBL 18 1.8V or Adj AAG
MAX1819EBL 20 2V or Adj AAC
MAX1819EBL 25 2.5V or Adj AAD
MAX1819EBL 33 3.3V or Adj AAE
MAX1819EBL 50 5V or Adj AAF
Selector Guide
Typical Operating Circuit
NC
MAX1819
IN
ON
OFF
CIN
1µF
SHDN
OUT
POK
GNDSET
COUT
3.3µF
VOUT
TO
µC
VIN = 2.5V TO 5.5V
RPOK
100kΩ
Pin Configuration
IN SHDN
GND
OUT
UCSP
(TOP OF PC BOARD/
BALLS SOLDERED DOWN)
A1 A3
C1 C3
A
B
C
123
TOP VIEW
POK
A2
SET
C2
MAX1819
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.
UCSP is a trademark of Maxim Integrated Products, Inc.
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
2_______________________________________________________________________________________
500mA Low-Dropout
Linear Regulator in
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = (VOUT + 500mV) or VIN = 2.5V, whichever is greater; SHDN = IN, TA= -40°C to +85°C, unless otherwise noted. Typical values
are at TA= +25°C.) (Note 2)
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 (VIN + 0.3V)
Output Short-Circuit Duration ...............................................1min
Continuous Power Dissipation (TA= +70°C) (Note 1)
6-Pin UCSP (derate 10.5mW/°C above +70°C) ............840mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Soldering Temperature (10s) ...........................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
Input Voltage VIN 2.5 5.5 V
Input Undervoltage Lockout
VUVLO
Rising, 75mV hysteresis 2.0
2.15
2.3 V
IOUT = 100mA, TA = +25°C, VOUT ≥ 2V -1 +1
IOUT = 100mA, TA = +25°C, VOUT < 2V
-1.5 +1.5
IOUT = 100mA, TA = -40°C to +85°C
-2.5 +2.5
Output Voltage Accuracy
(Preset Mode) VOUT
IOUT = 1mA to 500mA, VIN > VOUT + 0.5V,
TA = -40°C to +85°C-3 +3
%
Adjustable Output
Voltage Range
1.25 5.00
V
TA = 0°C to +85°C
1.225 1.250 1.275
SET Voltage Threshold
(Adjustable Mode) VSET
VIN = 2.7V,
IOUT = 100mA,
VOUT set to 2V TA = -40°C to +85°C
1.213 1.288
V
Guaranteed Output Current
(RMS) IOUT VIN ≥ 2.7V
500
mA
Short-Circuit Current Limit ILIM VOUT = 0, VIN ≥ 2.7V
0.55 1.39 2.50
A
In-Regulation Current Limit VOUT > 96% of nominal value, VIN ≥ 2.7V 2 A
SET Dual Mode™ Threshold 50 100 150 mV
SET Input Bias Current ISET VSET = 1.25V
-100 +100
nA
IOUT = 100µA 125 250
Ground-Pin Current IQIOUT = 500mA 150 µA
VOUT = 5V 125 220
VOUT = 3.3V 133 232
Dropout Voltage (Note 3)
VIN - VOUT
IOUT = 500mA
VOUT = 2.5V 165 280
mV
Line Regulation
∆VLNR
VIN from (VOUT + 100mV) to 5.5V,
ILOAD = 5mA
-0.15
0
+0.15
%/V
Dual Mode is a trademark of Maxim Integrated Products, Inc.
Note 1: Thermal properties are specified with product mounted on PC board with one square-inch of copper area and still air.
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VIN = (VOUT + 500mV) or VIN = 2.5V, whichever is greater; SHDN = IN, TA= -40°C to +85°C, unless otherwise noted. Typical values
are at TA= +25°C.) (Note 2)
Note 2: All devices are 100% production tested at TA= +25°C and up to 100mA. Limits over the operating temperature range and
above 100mA are guaranteed by design.
Note 3: The dropout voltage is defined as VIN - VOUT, when VOUT is 100mV below the value of VOUT measured for VIN = VOUT(NOM)
+ 500mV. Since the minimum input voltage is 2.5V, this specification is only meaningful when VOUT(NOM) > 2.5V. For
VOUT(NOM) between 2.5V and 3.5V, use the following equations: Typical Dropout = -40mV/V ✕VOUT(NOM) + 265mV;
Guaranteed Maximum Dropout = -60mV/V ✕VOUT(NOM) + 430mV. For VOUT(NOM) > 3.5V, Typical Dropout = 125mV;
Maximum Dropout = 220mV.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
UNITS
Load Regulation
∆VLDR
IOUT = 1mA to 500mA 0.4 1.0 %
Output Voltage Noise 10Hz to 1MHz, COUT = 3.3µF (ESR < 0.1Ω)115
µVRMS
SHUTDOWN
Shutdown Supply Current IOFF SHDN = GND, VIN = 5.5V 0.1 15 µA
VIH 2.5V < VIN < 5.5V 1.6
SHDN Input Threshold VIL 2.5V < VIN < 5.5V 0.6 V
SHDN = IN or GND, TA = +25°C 1 70
SHDN Input Bias Current I SHDN TA = +85°C 5 nA
POK OUTPUT
POK Output Low Voltage VOL POK sinking 1mA
0.01
0.1 V
Operating Voltage Range for
Valid POK POK sinking 100µA 1.0 5.5 V
POK = 5.5V, TA = +25°C 1 30
POK Output High
Leakage Current TA = +85°C 5 nA
POK Threshold Rising edge, referred to VOUT(NOMINAL) 90 93 96 %
THERMAL PROTECTION
Thermal Shutdown Temperature
TSHDN
170 °C
Thermal Shutdown Hysteresis
∆TSHDN
20 °C
Typical Operating Characteristics
(VIN = (VOUT + 500mV) or 2.5V, whichever is greater; SHDN = IN, CIN = 3.3µF, COUT = 3.3µF, TA= +25°C, unless otherwise noted.)
01.01.50.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
GROUND-PIN CURRENT
vs. INPUT VOLTAGE
MAX1819 toc01
INPUT VOLTAGE (V)
GROUND-PIN CURRENT (µA)
0
50
25
125
100
75
150
175
225
200
250
6.0
3.3V OUTPUT
1.8V OUTPUT
2.5V OUTPUT
IOUT = 150mA
115
135
125
155
145
175
165
GROUND-PIN CURRENT
vs. LOAD CURRENT
MAX1819 toc02
LOAD CURRENT (A)
GROUND-PIN CURRENT (µA)
0 0.2 0.3 0.4 0.50.1 0.6 0.7 0.8 0.9 1.0
3.3V OUTPUT
2.5V OUTPUT
1.8V OUTPUT
130
140
160
150
170
180
-40 10-15 35 60 85
GROUND-PIN CURRENT
vs. TEMPERATURE
MAX1819 toc03
TEMPERATURE (°C)
GROUND-PIN CURRENT (µA)
1.5V OUTPUT
5V OUTPUT
ILOAD = 150mA
-1.0
-0.8
-0.4
-0.6
0
-0.2
0.2
0.4
0.8
0.6
1.0
OUTPUT VOLTAGE ACCURACY
vs. LOAD CURRENT
MAX1819 toc05
LOAD CURRENT (A)
OUTPUT VOLTAGE ACCURACY (%)
00.20.3 0.40.1 0.5 0.6 0.7 0.90.8 1.0
VOUT = 3.3V
VOUT = 1.8V
VOUT = 0.5V
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
4_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VIN = (VOUT + 500mV) or 2.5V, whichever is greater; SHDN = IN, CIN = 3.3µF, COUT = 3.3µF, TA= +25°C, unless otherwise noted)
0
100
40
20
120
140
180
160
260
0100
80
60
200
200
220
240
400 500 600 700 800
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX1819 toc04
LOAD CURRENT (A)
DROPOUT VOLTAGE (mV)
300
VOUT = 3.3V
TA = +85°C
TA = +25°C
TA = -40°C
-0.5
-0.2
-0.3
-0.4
-0.1
0
0.1
0.2
0.3
0.4
0.5
OUTPUT VOLTAGE ACCURACY
vs. TEMPERATURE
MAX1819 toc06
TEMPERATURE (°C)
OUTPUT VOLTAGE ACCURACY (%)
-40 -15 10 35 60 85
ILOAD = 150mA
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX1819 toc07
80
0
20
10
PSRR (dB)
40
30
50
60
70
0.01 0.1 1 10 100 1000
FREQUENCY (kHz)
COUT = 3.3µF
VOUT = 3.3V
RLOAD = 100Ω
LINE TRANSIENT
MAX1819 toc08
VIN
VOUT 10mV/div
3.5V
100µs/div
3V
VOUT = 2.5V
IOUT = 5mA
LOAD TRANSIENT RESPONSE
MAX1819 toc09
IOUT
VOUT
380mA
50mA
20mV/div
40µs/div
VIN = 3.8V
VOUT = 3.3V
LOAD TRANSIENT RESPONSE
NEAR DROPOUT
MAX1819 toc10
50mV/div
200mA
20mA
40µs/div
IOUT
VOUT
VIN = 3.35V
VOUT = 3.5V
POWER-ON RESET
MAX1819 toc11
VIN
VPOK
VOUT
0
0
0
2V/div
10ms/div
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
_______________________________________________________________________________________ 5
SHUTDOWN WAVEFORM
MAX1819 toc12
POK
SHUTDOWN
VOLTAGE
VOUT
0
0
2V/div
0
200µs/div
1.35
1.36
1.38
1.37
1.39
1.40
2.5 3.0 3.5 4.0 4.5 5.0 5.5
SHORT-CIRCUIT CURRENT LIMIT
vs. SUPPLY VOLTAGE
MAX1819 toc13
SUPPLY VOLTAGE (V)
SHORT-CIRCUIT CURRENT LIMIT (A)
VOUT(NOM) = 2V
Detailed Description
The MAX1819 is a low-dropout, low-quiescent-current
linear regulator designed primarily for battery-powered
applications. The device supplies loads up to 500mA
and is available with preset output voltages. As illustrat-
ed in Figure 1, the MAX1819 consists of a 1.25V refer-
ence, error amplifier, P-channel pass transistor, and
internal feedback voltage-divider.
The 1.25V reference is connected to the error amplifier,
which compares this reference with the feedback volt-
age and amplifies the difference. If the feedback voltage
is lower than the reference voltage, the pass-transistor
gate is pulled lower, which allows more current to pass
to the output and increases 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 inter-
nal resistive-divider connected to OUT or an external
resistor network connected to SET. The Dual Mode
comparator examines VSET and selects the feedback
path. If VSET is below 50mV, the internal feedback path
is used and the output is regulated to the factory-preset
voltage.
Pin Description
PIN
NAME
FUNCTION
A1 IN Regulator Input. Supply voltage can range from 2.5V to 5.5V. Bypass with a 1µF capacitor to GND (see the
Capacitor Selection and Regulator Stability section).
A2 POK Open-Drain POK Output. POK remains low while the output voltage (VOUT) is below the POK threshold.
Connect a 100kΩ pullup resistor from POK to OUT to obtain an output voltage.
A3
SHDN
Active-Low Shutdown Input. A logic low reduces supply current below 15µA. In shutdown, the POK and
OUT are low. Connect to IN for normal operation.
C1 OUT Regulator Output. Sources up to 500mA. Bypass with a 3.3µF low-ESR capacitor to GND. Use a 4.7µF
capacitor for output voltages below 2V.
C2 SET Voltage-Setting Input. Connect to GND for preset output. Connect to a resistive voltage-divider between
OUT and GND to set the output voltage between 1.25V and 5V.
C3 GND Ground
Typical Operating Characteristics (continued)
(VIN = (VOUT + 500mV) or 2.5V, whichever is greater; SHDN = IN, CIN = 3.3µF, COUT = 3.3µF, TA= +25°C, unless otherwise noted)
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
6_______________________________________________________________________________________
Additional blocks include an output current limiter, ther-
mal sensor, and shutdown logic.
Internal P-Channel Pass Transistor
The MAX1819 features a 0.25ΩP-channel MOSFET
pass transistor. Unlike similar designs using PNP pass
transistors, P-channel MOSFETs require no base drive,
which reduces quiescent current. PNP-based regula-
tors also waste considerable current in dropout when
the pass transistor saturates and use high base-drive
currents under large loads. The MAX1819 does not suf-
fer from these problems and consumes only 125µA of
quiescent current under heavy loads as well as in
dropout.
Output Voltage Selection
The MAX1819’s Dual Mode allows operation in either a
preset voltage mode or an adjustable mode. Connect
SET to GND to select the preset output voltage. The
two-digit part number suffix identifies the output voltage
(see the Selector Guide). For example, the
MAX1819EBL33 has a preset 3.3V output voltage.
The output voltage may also be adjusted by connecting
a voltage-divider from OUT to SET to GND (Figure 2).
Select R2 in the 25kΩto 100kΩrange. Calculate R1
with the following equation:
R1 = R2 [(VOUT / VSET) - 1]
where VSET = 1.25V, and VOUT may range from 1.25V
to 5V.
Shutdown
Pull SHDN low to enter shutdown. During shutdown, the
output is disconnected from the input and supply cur-
rent drops to 0.1µA. When in shutdown, POK and OUT
pull low. SHDN can be pulled as high as 6V, regardless
of the input and output voltage.
100mV
SHDN
IN
POK
ON
OFF
CIN
1µF
VIN = 2.5V TO 5.5V
OUT VOUT = 1.25V TO 5V
COUT
3.3µF
THERMAL
SENSOR
SET
MOSFET
DRIVER WITH
ILIM
SHUTDOWN
LOGIC VREF
1.25V
ERROR
AMPLIFIER
GND
R1
R2
RPOK
100kΩ
LOGIC SUPPLY
VOLTAGE (VOUT)
93% VREF
TO
µC
5kΩ
MAX1819
Figure 1. Functional Diagram
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
_______________________________________________________________________________________ 7
POK Output
The power-OK (POK) output pulls low when OUT is less
than 93% of the nominal regulation voltage. Once OUT
exceeds 93% of the nominal voltage, POK goes high
impedance. POK is an open-drain N-channel output. To
obtain a voltage signal, connect a pullup resistor from
POK to OUT. A 100kΩresistor works well for most appli-
cations. POK can be used as a power-OK signal to a
microcontroller (µC), or drive an external LED to indicate
power failure. When the MAX1819 is shut down, POK is
held low independent of the output voltage. If unused,
leave POK grounded or unconnected.
Current Limit
The MAX1819 monitors and controls the pass transis-
tor’s gate voltage, limiting the output current to 1.0A
(typ). This current limit doubles when the output voltage
is within 4% of the nominal value to improve perfor-
mance with large load transients.
Thermal Overload Protection
Thermal overload protection limits total power dissipa-
tion in the MAX1819. When the junction temperature
exceeds TJ= +170°C, a thermal sensor turns off the
pass transistor, allowing the IC to cool. The thermal
sensor turns the pass transistor on again after the junc-
tion temperature cools by 20°C, resulting in a pulsed
output during continuous thermal overload conditions.
Thermal overload protection protects the MAX1819 in
the event of fault conditions. For continuous operation,
do not exceed the absolute maximum junction-temper-
ature rating of TJ= +150°C.
Operating Region and Power Dissipation
The MAX1819’s maximum power dissipation depends
on the thermal resistance of the IC package and circuit
board, the temperature difference between the die
junction and ambient air, and the rate of air flow. The
power dissipated in the device is P = IOUT ×(VIN -
VOUT). The maximum allowed power dissipation is
840mW at TA= +70°C or:
PMAX = (TJ(MAX) - TA) / ( θJB + θBA)
where TJ- TAis the temperature difference between
the MAX1819 die junction and the surrounding air, θJB
is the thermal resistance of the junction to the base,
and θBA is the thermal resistance through the PC
board, copper traces, and other materials to the sur-
rounding air. For best heatsinking, the copper area
should be equally shared between the IN, OUT, and
GND pins.
The MAX1819 delivers up to 0.5A RMS and operates
with input voltages up to 5.5V, but not simultaneously.
High output currents can only be sustained when input-
output differential voltages are low, as shown in Figure 3.
OUT
SET
GND
IN
SHDN
POK
COUT
3.3µF
VOUT
VOUT
CIN
1µF
ON
OFF
VIN = 2.5V TO 5.5V
R2
R1 = R2 - 1
1.25V
MAX1819 R1
Figure 2. Adjustable Output Using External Feedback
Resistors
2.5 3.53.0 4.0 4.5 5.0 5.5 6.0
MAX1819 fig03
INPUT VOLTAGE (V)
MAXIMUM OUTPUT CURRENT (mA)
0
200
400
600
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
(POWER DISSIPATION LIMIT)
MAXIMUM RECOMMENDED
OUTPUT CURRENT
VOUT = 2.5V
VOUT = 1.8V
VOUT = 3.3V
TA = +85°C
MAXIMUM INPUT VOLTAGE
TA = +70°C
Figure 3. Power Operating Regions—Maximum Output vs.
Supply Voltage
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
8_______________________________________________________________________________________
Applications Information
Capacitor Selection and
Regulator Stability
Capacitors are required at the MAX1819’s input and
output for stable operation over the full temperature
range and with load currents up to 500mA. Connect a
1µF capacitor between IN and ground and a 3.3µF low-
ESR capacitor between OUT and ground. For output
voltages less than 2V, use a 4.7µF low-ESR output
capacitor. The input capacitor (CIN) lowers the source
impedance of the input supply. Reduce noise and
improve load-transient response, stability, and power-
supply rejection by using larger output capacitors, such
as 10µF.
The output capacitor’s (COUT) equivalent series resis-
tance (ESR) affects stability and output noise. Use out-
put capacitors with an ESR of 0.1Ωor less to ensure
stability and optimum transient response. Surface-
mount ceramic capacitors have very low ESR and are
commonly available in values up to 10µF. CIN and
COUT use short traces to connect to the MAX1819.
Noise, PSRR, and Transient Response
The MAX1819 is designed to operate with low dropout
voltages and low quiescent currents in battery-powered
systems while still maintaining good noise, transient
response, and AC rejection. See the Typical Operating
Characteristics for a plot of Power-Supply Rejection
Ratio (PSRR) vs. Frequency. When operating from noisy
sources, improved supply-noise rejection and transient
response can be achieved by increasing the values of
the input and output bypass capacitors and through
passive filtering techniques.
The MAX1819 load-transient response (see the Typical
Operating Characteristics) shows two components of
the output response: a DC shift from the output imped-
ance due to the load current change, and the transient
response. Increasing the output capacitor’s value and
decreasing the ESR attenuates the overshoot.
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differential
(dropout voltage) determines the lowest usable supply
voltage. In battery-powered systems, this determines the
useful end-of-life battery voltage. Because the MAX1819
uses a P-channel MOSFET pass transistor, its dropout
voltage is a function of drain-to-source on-resistance
(RDS(ON)) multiplied by the load current (see the Typical
Operating Characteristics).
VDROPOUT = VIN - VOUT = RDS(ON) × IOUT
The MAX1819 ground current remains at approximately
150µA in dropout.
Chip Information
TRANSISTOR COUNT: 845
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ______________________9
©2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
MAX1819
500mA Low-Dropout Linear Regulator in UCSP
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)