LX8942IDT [MICROSEMI]
Low Dropout Dual Regulator; 低压差稳压双
| 型号： | LX8942IDT |
| 厂家： | 
Microsemi |
| 描述： | Low Dropout Dual Regulator |
| 文件： | 总8页 (文件大小：234K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LX8942
®
Low Dropout Dual Regulator
TM
PRODUCTION DATA SHEET
KEY FEATURES
DESCRIPTION
dual The high current regulator has over
2% Internally Trimmed Output
Two regulated outputs
Output current in excess of
1000mA
Low quiescent current standby
regulator
Drop-out Voltage, Input-output
differential <0.6V at 0.5A
Reverse battery protection
60V load dump protection
-50V reverse transient protection
Short circuit protection
Internal thermal overload
protection
The Microsemi LX8942 is
a
8.2V/5V positive voltage regulator. One voltage shutdown to protect both the internal
output is a high current (up to 1000mA) circuitry and the load during line transients,
regulator that can be turned on or off by a such as load dump (60V). In addition, the
high impedance low current TTL high current regulator design also has built-
compatible switch. The second or standby in protection for short circuit and thermal
output remains on regardless. The on/off overload. During these fault conditions of
switch not only shuts off the high current the primary output, the standby regulator
output but actually puts the IC in a will continue to power its load.
micropower
quiescent
mode,
current.
achieving
This
low
The LX8942 is the 8.2 volt, ±5% version
unique of a family of dual regulators with a standby
characteristic coupled with an extremely output voltage of 5V. Other high-current
low dropout, (0.55V for output current of outputs programmed for 5V and 12V
10mA) makes the LX8942 well suited for regulation are available in the SG29055,
power systems that require standby SG29125 devices. They are designed to
memory. The LX8942 includes other function over the full automotive ambient
features which were originally designed temperature range of -40°C to 85°C.
for automotive applications. These include
ON/OFF switch for high current
output
Surface Mount TO-252
APPLICATIONS
protection
from
reverse
battery
installations, double battery jumps and
load dump (transients).
Automotive electronics for
controls, entertainment and
safety functions
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
Continuous operation systems
PRODUCT HIGHLIGHT
* Required close to regulator package.
** Required for stability. May be increased without bound.
Input Voltage
(VIN)
Capacitor must be rated to operate at the minimum
temperature expected for the regulator system.
C1*
0.1µF
1
Output Voltage (VOUT1)
(8.2V, 1000mA)
2
Over Voltage
Thermal
Shutdown
C2 **
47µF
+
-
Regulator
Bias
ON/OFF Switch (for
output voltage only)
4
1.23V
Reference
Standby Output (VSB)
(5V, 60mA)
5V Standby
Regulator
5
LX8942
C3**
3
100µF
Ground
PACKAGE ORDER INFO
Plastic TO-252
5-Pin
DT
TJ (°C)
-40 to 85
RoHS Compliant / Pb-free
LX8942IDT
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX8942IDT-TR)
Copyright © 2005
Rev. 1.2, 2006-01-20
Microsemi
Integrated Products Division
Page 1
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8942
®
Low Dropout Dual Regulator
TM
PRODUCTION DATA SHEET
ABSOLUTE MAXIMUM RATINGS
PACKAGE PIN OUT
GROUND
Input Voltage (VIN) Operating .......................................................................................26V
Input Voltage (VIN) Over Voltage Transient.................................................... -15V to 60V
ON/OFF Switch ................................................................................................-0.3V to VIN
Operating Ambient Temperature Range ..................................................... -40°C to +85°C
Storage Temperature Range (TSTG)..............................................................-65°C to 150°C
Maximum Operating Junction Temperature (TJ) ....................................................... 150°C
STANDBY OUTPUT (VSB)
ON/OFF SWITCH
GROUND
OUTPUT VOLTAGE (VOUT1
)
INPUT VOLTAGE (VIN
DT PACKAGE
(Top View)
)
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
RoHS / Pb-free 100% matte Tin Lead Finish
Note: The heat sink tab is the Ground
Connection for this package.
THERMAL DATA
Plastic TO-252 5-Pin
DT
THERMAL RESISTANCE-JUNCTION TO CASE, θJC
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
9°C/W
80°C/W
Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the
above assume no ambient airflow.
FUNCTIONAL PIN DESCRIPTION
Name
VIN
Description
Input Voltage Supply.
VOUT1
GND
+8.2V Output Voltage at up to 1000mA.
Regulator Ground.
ON/OFF
VSB
TTL Logic level input control for turning ON and OFF the high current VOUT1 regulator.
+5V Standby Output Voltage at up to 60mA.
RECOMMENDED OPERATING CONDITIONS
Range over which the device is functional.
LX8942
Typ
Parameter
Symbol
Units
Min
9
Max
26
0.8
Input Voltage
VIN
VIL
VIH
V
V
V
mA
V
µF
V
ON/OFF Threshold Voltage Low Level, (VOUT1 is OFF)
ON/OFF Threshold Voltage High level, (VOUT1 is ON)
Load Current VOUT1 (with adequate heatsinking)
Maximum Line Transient (Load Dump) VSB < 6V
Input Capacitor (VIN to GND)
Reverse Polarity D.C. Input Voltage (VIN) (VOUT1 > -0.6V, 16Ω Load)
Reverse Polarity Transient Input Voltage (VIN) (1% Duty Cycle, T <
100ms, VOUT1 > -9V, 16Ω Load)
2
5
1000
60
0.1
-15
-50
V
Output Capacitor (VOUT1 to GND & VSB to GND)
Output Capacitor ESR Value
10
0.5
µF
Ω
5.0
Copyright © 2005
Rev. 1.2, 2006-01-20
Microsemi
Page 2
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8942
®
Low Dropout Dual Regulator
TM
PRODUCTION DATA SHEET
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C ≤ TA ≤ 70°C except where
otherwise noted and the following test conditions: TA = 25°C, VIN = 14V, IO1 = 50mA for VOUT1 and 10mA for VSB and are for DC
characteristics only. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the
ambient temperature.
LX8942
Typ
Parameter
Symbol
Test Conditions
Units
Min
Max
VOLTAGE OUTPUT (VOUT1) SECTION
`
Output Voltage (NOTE 1)
VOUT1
9V < VIN < 26V, IO1 < 1000mA
9V < VIN < 16V, IO1 = 5mA
9V < VIN < 26V, IO1 = 5mA
7.6
8.0
4
10
10
200
2
8.4
25
50
50
V
mV
mV
mV
mΩ
mA
mA
mA
Line Regulation
Load Regulation
Output Impedance
5mA < IO1 < 1000mA
500mADC and 10mARMS, 100Hz – 10kHz
IO1 < 10mA, No Load on Standby
IO1 = 500mA, No Load on Standby
IO1 = 750mA, No Load on Standby
40
90
100
Quiescent Current
Output Noise Voltage
Long Term Stability
Ripple Rejection
10Hz – 100kHz
100
20
µVRMS
mV /
1000hr
dB
FO1 = 120Hz
IO1 = 500mA
IO1 = 1000mA
66
0.45
0.7
0.60
1.2
V
V
Dropout Voltage
Current Limit
Maximum Operational Input
Voltage
Maximum Line Transient
ON / OFF Switch
ON / OFF Switch
1.0
26.5
60
1.8
A
VIN
Double Battery
31
70
V
VIN
IIH
IIL
VO1 < 9V
IO1 = 10mA, Pin 4 = 2.4V
IO1 = 10mA, Pin 4 = 0.4V
V
µA
µA
10
-10
STANDBY OUTPUT (VSB) SECTION
Output Voltage (Note 1)
Line Regulation
`
VSB
6V < VIN < 26V, ISB < 60mA
6V < VIN < 26V
1mA < ISB < 35mA
4.75
5.0
4
10
25
1
5.25
50
25
V
mV
mV
mV
Ω
mA
µVRMS
mV /
1000hr
dB
Load Regulation
1mA < ISB < 60mA
50
Output Impedance
Quiescent Current
Output Noise Voltage
1mADC and 1mARMS, 100Hz – 10kHz
ISB < 10mA, VOUT1 OFF
10Hz – 100kHz
1.2
300
3
Long Term Stability
20
Ripple Rejection
Dropout Voltage
Current Limit
FSB = 120Hz
ISB < 60mA
66
0.55
100
70
0.70
V
mA
V
60
60
Maximum Line Transient
VIN
4.75V < VSB < 6V
Note 1: The Temperature Extremes are Guaranteed but not 100% Production Tested.
Copyright © 2005
Rev. 1.2, 2006-01-20
Microsemi
Page 3
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8942
®
Low Dropout Dual Regulator
TM
PRODUCTION DATA SHEET
TYPICAL CIRCUIT WAVEFORMS
60V
Load Dump
Double Battery
33V
26V
14V
INPUT VOLTAGE
PIN 1(V)
14V
0V
4V
2V
ON/OFF SWITCH
0.8V
8.2V
8.2V
8.2V
8.2V
8.2V
5V
0V
OUTPUT
VOLTAGE 2 (V)
3.5V
5V
STANDBY
VOLTAGE
PIN 5 (V)
3.7V
LINE
NOISE,
ETC.
VOUT
SHORT
CIRCUIT
System
Conditions
TURN
ON
LOAD
DUMP
LOW
VIN
THERMAL
SHUTDOWN
TURN
OFF
Copyright © 2005
Rev. 1.2, 2006-01-20
Microsemi
Page 4
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8942
®
Low Dropout Dual Regulator
TM
PRODUCTION DATA SHEET
APPLICATION NOTE
The advantages of using a low-dropout regulator such as
the LX8942 are the need for less “headroom” for full
regulation, and the inherent reverse polarity protection
provided by the PNP output device. A typical NPN
regulator design requires an input to output differential of
approximately two volts minimum. This is due to the 2Vbe
+ Vcesat of the NPN Darlington used in the output, coupled
with the voltage drop across the current limit resistor. In
contrast, the “PNP Regulator” uses a single series pass
transistor with its single Vcesat, thus the lower input to
output voltage differential or dropout voltage.
In addition to a low dropout voltage, an important
advantage of the LX8942 series is low quiescent current in
the standby mode. When the high current or primary
regulator is shut off, the regulator enters a micropower
mode. Here all but the most essential circuitry to power the
standby output is deactivated. This allows the lowest
possible quiescent current (typical around 1.2mA), a vital
factor when used in a battery powered system.
The output capacitors chosen should be rated for the full
range of ambient temperature over which the circuit will be
exposed and expected to operate. For example, many
aluminum type electrolytic capacitors will freeze at -30°C.
The effective capacitance is reduced to zero in such a
situation. Capacitors rated for -40°C operation must be
used in order to maintain regulator stability at that
temperature. Tantalum capacitors satisfy this requirement.
STANDBY OUTPUT
The LX8942 differs from most fixed voltage regulators
in that it is equipped with two regulator outputs instead of
one. The additional output is intended for use in systems
requiring standby memory circuits. While the high current
regulator output can be controlled with the ON/OFF pin
described below, the standby remains on under all
conditions as long as sufficient input voltage is applied to
the IC. Thus, memory and other circuits powered by this
output remain unaffected by positive line transients,
thermal shutdown, etc.
In some applications the regulator output voltage is used
not only as a power supply but also as a voltage reference
for control systems. In such cases not just the temperature
stability of the output is important but also the initial
accuracy. The LX8942 fills this need as the internal
bandgap reference is trimmed allowing a typical output
voltage tolerance of ±1%.
The standby regulator circuit is designed so that the
quiescent current to the IC is very low (<1.5mA) when the
other regulator output is off.
If the standby output is not required it can be disabled.
This is accomplished by connecting a resistor from the
standby output to the supply voltage, thereby also
eliminating the requirement for a more expensive output
capacitor to prevent unwanted oscillations. The resistor
value depends upon the minimum input voltage expected
for a given system. Since the standby output is shunted
with an internal 5.6V zener, the current through the
external resistor should be sufficient to bias internal
resistors up to this point. Approximately 60mA will
suffice, resulting in a 10k external resistor for most
applications (Figure 1).
EXTERNAL CAPACITORS
To stabilize the outputs and prevent oscillation (perhaps
by many volts) external capacitors are required. The
minimum recommended value for the output capacitors is
47μF for the 8.2V output and 100µF for the 5V output. The
actual size and type will likely vary according to the
particular application, e.g., operating temperature range and
load. Another consideration is the effective series resistance
(ESR) of the capacitor. Capacitor ESR will vary by
manufacturer. Consequently, some evaluation may be
required to determine the minimum value of the output
capacitors. Generally worst case occurs at the maximum
load and minimum ambient temperature.
VIN
RD
10K
The size of the output capacitor can be increased to any
value above the minimum. One possible advantage of this
would be to maintain the output voltage during brief
periods of negative input transients.
Standby
Output
LX8942
C3
Figure 1 – Disabling Standby Output to Eliminate C3
Copyright © 2005
Rev. 1.2, 2006-01-20
Microsemi
Page 5
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8942
®
Low Dropout Dual Regulator
TM
PRODUCTION DATA SHEET
APPLICATION NOTE
The high current regulated output features fault
protection against over voltage as well as a thermal
shutdown feature. If the input voltage rises above 33V (load
dump), the high current output shuts down automatically.
The internal circuitry is thus protected and the IC is able to
survive higher voltage transients than might otherwise be
expected. The thermal shutdown of the high current output
effectively guards against overheating of the die since this
section of the IC is the principle source of power dissipation
on the chip.
ON/OFF SWITCH
The ON/OFF pin is a high impedance low current
switch that controls the main output voltage (pin 2). This is
directly compatible with all 5 volt logic families. For use
with open collector logic outputs, a 100Kresistor from this
pin to a 5V supply, such as Pin 5, is required.
Copyright © 2005
Rev. 1.2, 2006-01-20
Microsemi
Page 6
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8942
®
Low Dropout Dual Regulator
TM
PRODUCTION DATA SHEET
PACKAGE DIMENSIONS
5-Pin Plastic TO-252
DT
E
A
MILLIMETERS
INCHES
b3
Dim
MIN
2.18
0
MAX
2.39
0.23
0.78
5.46
0.61
0.89
6.22
6.73
MIN
0.086
0
MAX
0.094
0.009
0.031
0.215
0.024
0.035
0.245
0.265
c2
L3
A
A1
b2
b3
0.62
5.00
0.45
0.46
5.96
6.35
0.024
0.197
0.018
0.018
0.235
0.250
D
C
H
c2
D
E
e
1.27 BSC
0.050 BSC
H
L
L3
Ø
9.40
1.08
0.89
0.85
10.41
1.40
1.27
1.62
0.370
0.043
0.035
0.033
0.410
0.055
0.050
0.064
L
e
C
b2
Note:
1. Dimensions do not include mold flash or protrusions;
these shall not exceed 0.155mm(.006”) on any side.
Lead dimension shall not include solder coverage.
A1
Copyright © 2005
Rev. 1.2, 2006-01-20
Microsemi
Page 7
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
LX8942
®
Low Dropout Dual Regulator
TM
PRODUCTION DATA SHEET
NOTES
PRODUCTION DATA – Information contained in this document is proprietary to
Microsemi and is current as of publication date. This document may not be modified in
any way without the express written consent of Microsemi. Product processing does not
necessarily include testing of all parameters. Microsemi reserves the right to change the
configuration and performance of the product and to discontinue product at any time.
Copyright © 2005
Rev. 1.2, 2006-01-20
Microsemi
Integrated Products Division
Page 8
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
相关型号：
©2020 ICPDF网 联系我们和版权申明