MAX8888EZK21 [MAXIM]
Fixed Positive LDO Regulator, 2.1V, BICMOS, PDSO5, LOW PROFILE, SOT-23, 5 PIN;
| 型号： | MAX8888EZK21 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Fixed Positive LDO Regulator, 2.1V, BICMOS, PDSO5, LOW PROFILE, SOT-23, 5 PIN 信息通信管理 光电二极管 |
| 文件： | 总8页 (文件大小：391K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1859; Rev 0; 12/00
Low-Dropout, 300mA Linear Regulators in SOT23
General Description
Features
o Guaranteed 300mA Ouput Current (500mA for
The MAX8887/MAX8888 low-dropout linear regulators
operate from a +2.5V to +5.5V input and deliver up to
300mA continuous (500mA pulsed) current. The
MAX8887 is optimized for low-noise operation, while the
MAX8888 includes an open-drain POK ouput flag. Both
regulators feature exceptionally low 100mV dropout at
200mA. These devices are available in a variety of pre-
set output voltages in the +1.5V to +3.3V range.
pulsed loads)
o Low 100mV Dropout at 200mA Load
o POK Output (MAX8888)
o 42µV
Ouput Noise (MAX8887)
RMS
o Preset Output Voltages (1.5V, 1.8V, 2.85V, and
3.3V)
An internal PMOS pass transistor allows the low 55µA
supply current to remain independent of load, making
these devices ideal for portable battery-powered equip-
ment such as personal digital assistants (PDAs), cellu-
lar phones, cordless phones, and notebook computers.
Other features include a micropower shutdown mode,
short-circuit protection, thermal shutdown protection,
and an active-low open-drain power-OK (POK) output
that indicates when the output is out of regulation. The
MAX8887/MAX8888 are available in a thin 5-pin SOT23
package that is only 1mm high.
o 55µA No-Load Supply Current
o Thermal-Overload and Short–Circuit Protection
o Foldback Ouput Current-Limit Protection
o 60dB PSRR at 1kHz
o 0.1µA Shutdown Current
o Thin 5-Pin SOT23 Package, 1mm High
Ordering Information
TEMP
RANGE
PIN-
PACKAGE
TOP
MARK
PART
MAX8887EZK15
-40°C to +85°C
5-SOT23
5-SOT23
5-SOT23
5-SOT23
5-SOT23
5-SOT23
5-SOT23
5-SOT23
5-SOT23
5-SOT23
ADQD
ADPX
ADPY
ADPZ
–
________________________Applications
MAX8887EZK18 -40°C to +85°C
MAX8887EZK29 -40°C to +85°C
MAX8887EZK33 -40°C to +85°C
MAX8887EZKxy* -40°C to +85°C
Notebook Computers
Wireless Handsets
PDAs and Palmtop Computers
Digital Cameras
MAX8888EZK15
-40°C to +85°C
ADQE
ADQA
ADQB
ADQC
–
PCMCIA Cards
MAX8888EZK18 -40°C to +85°C
MAX8888EZK29 -40°C to +85°C
MAX8888EZK33 -40°C to +85°C
MAX8888EZKxy* -40°C to +85°C
Hand-Held Instruments
*Other versions (xy) between +1.5 and +3.3V are available in
100mV increments. Contact factory for other versions. Minimum
order quantity is 25,000 units.
Typical Operating Circuit
Pin Configurations
V
OUT
300mA
INPUT
+2.5V TO +5.5V
IN
OUT
TOP VIEW
C
C
OUT
IN
2.2µF
2.2µF
MAX8887
MAX8888
IN
GND
1
2
3
5
4
OUT
IN
GND
1
2
3
5
OUT
POK
(BP)
ON
MAX8887
MAX8888
SHDN
OFF
C
BP
GND
0.01µF
SHDN
BP
SHDN
4
POK
( ) ARE FOR MAX8887 ONLY.
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Low-Dropout, 300mA Linear Regulators in SOT23
ABSOLUTE MAXIMUM RATINGS
IN, SHDN, POK, to GND........................................-0.3V to +6.0V
OUT, BP to GND............................................-0.3 to (V + 0.3V)
Output Short-Circuit Duration.....................................Continuous
Operating Temperature Ranges..........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+500°C
IN
Continuous Power Dissipation (T = +70°C)
A
5-Pin SOT23 (derate 9.1mW/°C above +70°C)............727mW
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 = V
+ 1V, SHDN = IN, T = -40°C to +85°C, unless otherwise noted.) (Note 1)
A
IN
OUT
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage
V
2.5
5.5
V
IN
V
rising
IN
Input Undervoltage Lockout
2.15
-1.2
-2
2.4
+1.2
+2
V
(2% typical hysteresis)
T
A
= +25°C, I
= 100mA
OUT
I
= 100µA to 300mA,
= 0°C to +85°C
OUT
Output Voltage Accuracy
%
T
A
I
= 100µA to 300mA
-3
+3
OUT
Continuous
10ms pulse
300
Maximum Output Current
Current Limit
mA
mA
µA
500
300
420
V
V
= 0
OUT
OUT
> 93% of nominal value
No load
55
65
100
Ground-Pin Current
I
= 300mA
OUT
0.5
I
I
I
= 1mA
OUT
OUT
OUT
Dropout Voltage (Note 2)
Line Regulation
V
= +3.3V
mV
= 200mA
= 300mA
100
150
200
OUT
V
=2.5V or (V
= 5mA
+ 0.4V) to 5.5V,
IN
OUT
-0.15
0
0.15
%/V
I
OUT
10Hz to 100kHz, C = 0.01µF,
BP
MAX8887
MAX8888
MAX8887
MAX8888
42
360
60
40
C
= 2.2µF, ESR
< 0.1Ω
OUT
COUT
Output Noise
PSRR
µV
RMS
10Hz to 100kHz, C
= 2.2µF,
OUT
ESR
< 0.1Ω
COUT
f < 1kHz, C = 0.01µF,
BP
C
= 4.7µF, ESR
< 0.1Ω
OUT
COUT
dB
f < 1kHz, C
= 2.2µF,
OUT
ESR
< 0.1Ω
COUT
2
_______________________________________________________________________________________
Low-Dropout, 300mA Linear Regulators in SOT23
ELECTRICAL CHARACTERISTICS (continued)
(V = V
+ 1V, SHDN = IN, T = -40°C to +85°C, unless otherwise noted.) (Note 1)
A
IN
OUT
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SHUTDOWN
Shutdown Supply Current
SHDN = GND, V = 5.5V
0.1
2
µA
V
IN
V
2.5V ≤ V ≤ 5.5V
1.6
IH
IN
SHDN Input Threshold
V
2.5V ≤ V ≤ 5.5V
0.6
IL
IN
SHDN Input Bias Current
SHDN = IN or GND
10
100
nA
Ω
OUT Discharge Resistance in
Shutdown
SHDN = GND
650
1100
POK (MAX8888 ONLY)
POK Trip Level, Referred to OUT
Set Point
V
falling
OUT
90
92.5
95
%
V
(1% typical hysteresis)
Operating IN Voltage Range for
Valid POK
1.0
5.5
POK Output Voltage Low
V
I
= 1mA
0.1
V
OL
SINK
POK Output Leakage Current
THERMAL PROTECTION
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
V
= 5.5V, SHDN = IN
100
nA
POK
170
20
°C
°C
Note 1: All parts are 100% tested at T = +25°C. Limits over the operating temperature range are guaranteed by design.
A
Note 2: Typical and maximum dropout voltage for different output voltages are shown in Typical Operating Characteristics curve.
Typical Operating Characteristics
(Typical Operating Circuit, T = +25°C, unless otherwise noted.)
A
OUTPUT VOLTAGE ACCURACY
vs. LOAD CURRENT
OUTPUT VOLTAGE ACCURACY
vs. TEMPERATURE
OUTPUT VOLTAGE vs. INPUT VOLTAGE
0.05
0.04
0.03
0.02
0.01
0.0
1.0
0.8
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
I
V
= 0
OUT
I
= 0
OUT
= V + 500mV
OUT
IN
0.6
I
= 300mA
OUT
0.4
0.2
0.0
-0.01
-0.02
-0.03
-0.04
-0.05
-0.2
-0.4
-0.6
-0.8
-1.0
0
50
100
150
200
250
300
-40
-15
10
35
60
85
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
Low-Dropout, 300mA Linear Regulators in SOT23
Typical Operating Characteristics (continued)
(Typical Operating Circuit, T = +25°C, unless otherwise noted.)
A
DROPOUT VOLTAGE vs. OUTPUT VOLTAGE
DROPOUT VOLTAGE vs. LOAD CURRENT
GROUND-PIN CURRENT vs. INPUT VOLTAGE
300
250
200
150
100
50
160
140
120
100
80
150
I
= 200mA
OUT
125
100
75
50
25
0
T
= +25°C
A
MAXIMUM
TYPICAL
T
= +85°C
A
I
= 300mA
LOAD
60
I
= 0
LOAD
T
A
= -40°C
40
20
0
0
2.5
2.7
2.9
3.1
3.3
0
50
100
150
200
250
300
0
1.0
2.0
3.0
4.0
5.0
V
OUT
(V)
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
GROUND-PIN CURRENT vs. LOAD CURRENT
GROUND-PIN CURRENT vs. TEMPERATURE
70
100
80
60
40
20
0
70
60
I
= 0
OUT
OUT
68
66
64
62
60
58
56
54
52
50
V
= +5.5V
= +3.8V
IN
V
= V + 500mV
IN
C
C
= 2.2µF
OUT
= 0.01µF
BP
50
40
V
IN
30
20
V
LOAD
= +3.30V
= 30mA
OUT
10
0
I
MAX8887 ONLY
100 1000
0
50
100
150
200
250
300
-40
-15
10
35
60
85
0.01 0.1
1
10
LOAD CURRENT (mA)
TEMPERATURE (°C)
FREQUENCY (kHz)
MAX8887
OUTPUT NOISE DC TO 1MHz
LOAD-TRANSIENT RESPONSE
MAX8887-9 toc10
MAX8887-9 toc11
300mA
10mA
I
OUT
V
OUT
50µV/div
50mV/div
AC-COUPLED
V
OUT
V
= +3.3V
= +3.8V
OUT
V
IN
V
OUT
= +1.8V, V = 3.8V, I
= 15mA
LOAD
IN
TIME (40ms/div)
TIME (10µs/div)
4
_______________________________________________________________________________________
Low-Dropout, 300mA Linear Regulators in SOT23
Typical Operating Characteristics (continued)
(Typical Operating Circuit, T = +25°C, unless otherwise noted.)
A
LOAD-TRANSIENT RESPONSE
LINE-TRANSIENT RESPONSE
NEAR DROPOUT
MAX8887-9 toc12
MAX8887-9 toc13
300mA
+4.5V
+4V
I
OUT
10mA
V
IN
V
OUT
50mV/div
AC-COUPLED
V
OUT
20mV/div
AC-COUPLED
V
= +3.3V
= +3.4V
OUT
V
LOAD
= +3.3V
OUT
= 100mA
V
IN
I
TIME (10µs/div)
TIME (100µs/div)
SHUTDOWN WAVEFORM
POK WAVEFORM
MAX8887-9 toc14
MAX8887-9 toc15
V
OUT
= +3.3V, R
= 100Ω
LOAD
V
SHDN
V
IN
2V/div
2V/div
V
V
2V/div
2V/div
OUT
V
OUT
1V/div
DC-COUPLED
POK
V
OUT
= +3.3V, R
= 10Ω
LOAD
TIME (20µs/div)
TIME (20ms/div)
Pin Description
MAX8887
MAX8888
NAME
FUNCTION
Regulator Input. Supply voltage can range from 2.5V to 5.5V. Bypass with 2.2µF
capacitor to GND (see Capacitor Selection and Regulator Stability).
1
2
3
1
2
3
IN
GND
SHDN
Ground
Active-Low Shutdown Input. A logic low reduces the supply current to below 0.1µA.
In shutdown, POK and OUT are driven low. Connect to IN for normal operation.
Open-Drain Active-Low POK Output. POK remains low while the output voltage (V
) is
OUT
—
4
POK
below the reset threshold. Connect a 100kΩ pullup resistor to OUT to obtain a logic level
output. POK is driven low in shutdown. If not used, leave this pin unconnected.
4
5
—
BP
Reference Bypass. Bypass with a low-leakage 0.01µF ceramic capacitor.
Regulator Output. Sources up to 300mA guaranteed. Bypass with 2.2µF (<0.2Ω typical
ESR) ceramic capacitor to GND.
5
OUT
_______________________________________________________________________________________
5
Low-Dropout, 300mA Linear Regulators in SOT23
0.8A (typ). This current limit is reduced to 500mA (typ)
Detailed Description
when the output voltage is below 93% of the nominal
The MAX8887/MAX8888 are low-dropout, low-quies-
value to provide foldback current limiting.
cent-current linear regulators designed primarily for
battery-powered applications. The devices supply
loads up to 300mA and are available in several fixed
output voltages in the +1.5 to +3.3V range. The
MAX8887 is optimized for low-noise operation, while
the MAX8888 includes an open-drain POK output flag.
As illustrated in Figure 1, the MAX8888 consists of a
1.25V reference, error amplifier, P-channel pass tran-
sistor, and internal feedback voltage divider.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipa-
tion in the MAX8887/MAX8888. When the junction tem-
perature exceeds T =+170°C, a thermal sensor turns
J
off the pass transistor, allowing the device to cool. The
thermal sensor turns the pass transistor on again after
the junction temperature cools by 20°C, resulting in a
pulsed output during continuous thermal overload con-
ditions. Thermal overload protection protects the
MAX8887/MAX8888 in the event of fault conditions. For
continuous operation, do not exceed the absolute maxi-
Internal P-Channel Pass Transistor
The MAX8887/MAX8888 feature a 0.5Ω P-channel
MOSFET pass transistor. Unlike similar designs using
PNP pass transistors, P-channel MOSFETs require no
base drive, which reduces quiescent current. PNP-
based regulators also waste considerable current in
dropout when the pass transistor saturates and use
high base drive currents under large loads. The
MAX8887/MAX8888 do not suffer from these problems
and consume only 55µA of quiescent current under
heavy loads as well as in dropout.
mum junction-temperature rating of T =+150°C.
J
Operating Region and Power Dissipation
The MAX8887/MAX8888’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 = I
OUT
727mW or:
(V -
IN
OUT
V
). The maximum allowed power dissipation is
Ouput Voltage Selection
The MAX8887/MAX8888 are supplied with various fac-
tory-set output voltages ranging from 1.5V to 3.3V. The
part number’s two-digit suffix identifies the nominal out-
put voltage. For example, the MAX8887EUK33 has a
preset output voltage of 3.3V (see Ordering Infor-
mation).
P
MAX
= (T
- T ) / (θ + θ
)
CA
J(MAX)
A
JC
where T
-T is the temperature difference
A
J(MAX)
between the MAX8887/MAX8888 die junction and the
surrounding air; θ is the thermal resistance from the
JC
junction to the case; and θ
is the thermal resistance
CA
from the case through PC board, copper traces, and
other materials to the surrounding air.
Shutdown
Drive SHDN low to enter shutdown. During shutdown,
the output is disconnected from the input and supply
current drops to 0.1µA. When in shutdown, POK and
OUT are driven low. SHDN can be pulled as high as
6V, regardless of the input and output voltages.
Refer to Figure 2 for the MAX8887/MAX888 valid oper-
ating region.
Noise Reduction
For the MAX8887 only, an external 0.01µF bypass
capacitor at BP creates a lowpass filter for noise reduc-
tion. The MAX8887 exhibits 42µV
of output voltage
RMS
Power-OK Output
The power-OK output (POK) 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 logic level output, connect a pullup resistor
from POK to OUT. A 100kΩ resistor works well for most
applications. POK can be used as a power-on-reset
(POR) signal to a microcontroller (µC) or to drive other
logic. Adding a capacitor from POK to ground creates
POK delay. When the MAX8887 is shut down, POK is
held low independent of the output voltage. If unused,
leave POK grounded or unconnected.
noise with C
= 0.01µF and C
= 2.2µF (see
OUT
BP
Typical Operating Characteristics).
Applications Information
Capacitor Selection and Regulator
Stability
Connect a 2.2µF ceramic capacitor between IN and
ground and a 2.2µF ceramic capacitor between OUT
and ground. The input capacitor (C ) lowers the
IN
source impedance of the input supply. Reduce noise
and improve load-transient response, stability, and
power-supply rejection by using a larger ceramic out-
put capacitor such as 4.7µF.
Current Limit
The MAX8887/MAX8888 monitor and control the pass
transistor’s gate voltage, limiting the output current to
The output capacitor’s (C
) equivalent series resis-
OUT
tance (ESR) affects stability and output noise. Use out-
6
_______________________________________________________________________________________
Low-Dropout, 300mA Linear Regulators in SOT23
IN
SHDN
P
MOS DRIVER
WITH I
LIMIT
ERROR
AMP
SHUTDOWN
LOGIC
OUT
POK
MAX8888
POK
1.25V
REF
95%
REF
THERMAL
SENSOR
GND
Figure 1. Functional Diagram
put capacitors with an ESR of 0.1Ω or less to ensure sta-
bility and optimum transient response. Surface-mount
ceramic capacitors have very low ESR and are com-
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
(POWER DISSIPATION LIMIT)
monly available in values up to 10µF. Connect C and
IN
400
C
as close to the MAX8887/MAX8888 as possible to
OUT
T = +85°C
A
minimize the impact of PC board trace inductance.
T = +70°C
A
MAXIMUM RECOMMENDED OUTPUT CURRENT
Noise, PSRR, and Transient Response
The MAX8887/MAX8888 are designed to operate with
low dropout voltages and low quiescent currents in bat-
tery-powered systems while still maintaining excellent
noise, transient response, and AC rejection. See the
Typical Operating Characteristics for a plot of power-
supply rejection ratio (PSRR) versus 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.
300
200
100
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
(V - V ) (V)
IN
OUT
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differen-
tial (dropout voltage) determines the lowest usable sup-
ply voltage at which the output is regulated. In
battery-powered systems, this determines the useful
end-of-life battery voltage. The MAX8887/MAX8888 use
a P-channel MOSFET pass transistor. Its dropout volt-
age is a function of drain-to-source on-resistance
Figure 2. Power Operating Regions: Maximum Output Current
vs. Input Voltage
(R
) multiplied by the load current (see Typical
DS(ON)
Operating Characteristics).
Chip Information
✕
V
= V - V
= R
I
OUT
DROPOUT
IN
OUT
DS(ON)
TRANSISTOR COUNT: 620
PROCESS: BiCMOS
_______________________________________________________________________________________
7
Low-Dropout, 300mA Linear Regulators in SOT23
Package Information
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 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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