LM9073SX [NSC]
IC VREG DUAL OUTPUT, FIXED POSITIVE LDO REGULATOR, PSSO11, TO-263, 11 PIN, Fixed Positive Multiple Output LDO Regulator;
| 型号： | LM9073SX |
| 厂家： | 
National Semiconductor |
| 描述： | IC VREG DUAL OUTPUT, FIXED POSITIVE LDO REGULATOR, PSSO11, TO-263, 11 PIN, Fixed Positive Multiple Output LDO Regulator 输出元件 调节器 |
| 文件： | 总18页 (文件大小：718K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PRELIMINARY
April 2000
LM9073
Dual High Current Low-Dropout System Regulator
General Description
Features
n Two 5V regulated outputs:
The LM9073 is a high performance voltage regulator system
with operational and protection features that address many
requirements of automotive applications. Two regulated out-
puts are provided. The main regulator provides a precision
2% tolerance 5V output at 700mA with a low dropout charac-
teristic. The second output, an External Supply regulator,
provides a 5V output with 2% tolerance for load currents up
to 100mA. This External Supply output is fully protected from
short circuit to ground or the unregulated input supply (igni-
tion or battery potentials in automotive applications) which
makes it suitable for powering remotely located load circuits
or sub-systems.
n
n
700mA, 2% Main output
100mA, 2% External Supply output
n External Supply output protected from shorts to battery
n Good EMI (1MHz to 400MHz, BCI) immunity
n Separate ON/OFF and Keep-Alive control inputs
n Less than 100µA quiescent current in OFF state
n Programmable delayed reset output
n Adjustable threshold voltage for generating reset
n Built-in system watchdog timer
n Input transient protection over 60V to −45V
n Less than 1V dropout at full load
The LM9073 also contains a programmable delayed system
reset output. Two control inputs are provided. An ON/OFF in-
put intended for connection to an ignition switch, and a Keep
Alive input whereby a system can remain powered after igni-
tion has been switched OFF. Additionally, a watchdog func-
tion is built in to enhance system operationally reliability.
n Wide −40˚C to 125˚C operating temperature range
n Surface mount, TO−263 and standard TO−220 power
packages
Applications
n Automotive module supply power conditioning
n Remote sub−system powering
n Continuous operation for save routines and E2PROM
programing after power down command
n Safety relates systems − EMC operational with a system
watchdog monitor
For EMC concerns the LM9073 remains fully operational
and does not generate false rest signals while subjected to
greater than 100mA, 1MHz to 400MHz bulk current injection
signals on the input supply and External Supply output lines.
Connection Diagram
11 Lead TO−220 Package
11 Lead TO−263 Package
DS101296-2
Top View
DS101296-1
Order Number LM9073T
See NS Package Number TA11B
Top View
Order Number LM9073S
See NS Package Number TS11B
© 2000 National Semiconductor Corporation
DS101296
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Block Diagram
DS101296-3
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2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
In, C Watchdog
−0.3V to 7V
150˚C
Junction Temperature
Storage Temperature
−65˚C to 150˚C
2000V
ESD Susceptibility(Note 2)
Lead temperature (Soldering, 10 Sec)
265˚C
Input Voltage
−45V to 45V
60V
Input Voltage (transient, t≤400mS)
Forced Output Voltages
Main Output
Operating Ratings(Note 1)
−0.3V to 7V
−0.3V to 27V
−0.3V to 16V
Input Voltage Range
6V to 27V
External Supply Output
ON/OFF Input Voltage(Note 6)
ON/OFF Input Current
Ambient Temperature Range
−40˚C to 125˚C
Thermal Resistance
±
20mA
θJC
θJA
4˚C/W
Keep Alive In, Reset Out, CDELAY
Reset Adjust,Watchdog Trigger
,
43˚C/W
Electrical Characteristics
The following specifications apply for 6V ≤ vIN ≤ 19V, tCASE = 25˚C unless otherwise specified. COUT ≥ 6µF with 0.3Ω ≤ ESR
≤ 0.3Ω on each regulator output.
LM9073
Symbol
Parameter
Conditions
Units
Min
Max
MAIN REGULATOR
10mA ≤ ILOAD ≤ 700mA
4.9
4.8
5.1
5.2
V
V
VMAIN
Output Voltage
19V ≤ VIN ≤ VSD
,
5mA ≤ ILOAD ≤ 700mA
VIN = 16V, 10mA ≤ ILOAD
700mA
≤
RMLOAD
RMLINE
VMDO
Load Regulation
25
25
1
mV
mV
V
Line Regulation
ILOAD = 700mA, 8V ≤ VIN ≤ 16V
>
Dropout Voltage, VIN− VMAIN
VIN 5.5V, 10mA ≤ ILOAD
≤
700mA(Note 5)
Overvoltage Shutdown
Threshold
VSD
30
40
36
V
IMSC
PSRR
Output Short Circuit Current
RL = 1Ω
2000
mA
dB
VIN = 9V, 50Hz ≤ freq ≤ 20kHZ,
VRIPPLE = 4V
Ripple Rejection
P−P
External Supply Regulator
VEXT
Output Voltage
3mA ≤ ILOAD ≤ 100mA
4.9
4.8
5.1
5.2
V
V
19V ≤ VIN ≤ VSD
3mA ≤ ILOAD ≤ 100mA
VIN = 16V, 3mA ≤ ILOAD
100mA
≤
RELOAD
RELINE
VEDO
Load Regulation
25
25
mV
mV
V
Line Regulation
ILOAD = 100mA, 8V ≤ VIN ≤ 16V
>
VIN 5.5V, 3mA ≤ ILOAD
≤
Dropout voltage, VIN − VEXT
0.8
100mA (Note 5)
Overvoltage Shutdown
Threshold
VSD
30
36
V
IESC
Output Short Circuit Current
Output Short Circuit
RL = 1Ω
250
27
mA
V
VESC
No effect on other functions
−0.3
40
VIN = 9V, 50Hz ≤ freq ≤ 20kHZ,
VRIPPLE = 4VPP
PSRR
Ripple Rejection
dB
Input Current
IQOFF
8V ≤ VIN ≤ 16V
100
10
µA
mA
mA
Quiescent Input Current with
Both Regulators OFF.
16V ≤ VIN ≤ 42V
IQ
No Load Quiescent Current
8V ≤ VIN ≤ 19V, IL = 0mA
15
3
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Electrical Characteristics (Continued)
The following specifications apply for 6V ≤ vIN ≤ 19V, tCASE = 25˚C unless otherwise specified. COUT ≥ 6µF with 0.3Ω ≤ ESR
≤ 0.3Ω on each regulator output.
LM9073
Symbol
Parameter
Conditions
Units
Min
Max
Input Current
VIN ≥ 8V, ILTOTAL = IMAIN
+
Additional Input Current with
both Regulators ON
ILEXT
X
INON
1.2
ILTOTAL = 700mA + 100mA =
800mA
ILTOTAL
<
<
0V VIN 8V, (Note 4)
ILTOTAL = IMAIN + ILEXT
ILTOTAL = 700mA + 100mA =
800mA
X
Additional Input Current when in
Dropout
ILTOTAL
LINDO
1.5
Reset Output
VMAIN output controls Reset
Reset Adjust (pin 11 )open
circuited
4.0
4.2
V
VTHRL
Low Switching Threshold
Reset Adjust (pin 11) shorted to
ground
4.5
4.7
5.75
0.4
V
V
V
VTHRH
VLOW
High Switching Threshold
VMAIN output controls Reset
5.35
1V ≤ VMAIN ≤ VTHRL
RRESET = 50kΩ to VMAIN
Logic Low Output Threshold
Normal opeation,
VMAIN
−50mV
VHIGH
Logic High Output Threshold
V
THRL≤ VMAIN
≤
THRH,, I
VMAIN
V
SOURCE
= 0
RP−U
Internal Pull-Up Resistance
Reset Delay Interval
2.4
35
6.0
70
kΩ
TDELAY
CDELAY = 0.1µF
mS
From 10% VMAIN to 90% VMAIN
CLRESET = 50pF
TRISE
TFALL
Output Rise Time
Output Fall Time
1.5
0.5
µS
µS
From 90% VMAIN to 10% VMAIN
CLRESET = 50pF
Watchdog
VTRIGL
Trigger Input Logic Low Voltage
Trigger Input Logic High Level
.08
70
V
V
VTRIGR
2
CWATCHDOG = 0.1µF (low
leakage)
IWATCHDOG for charging the
watchdog
TWD
Watchdog Refresh Window
35
mS
TPW
Watchdog Trigger Pulse Width
10
5
µS
Trigger Input Pull-down
Resistance
RTRIG
40
kΩ
Control Inputs
VON
ON Threshold for ON/OFF Input
Rseries = 22kΩ
3.5
1.5
4.5
2.5
V
V
OFF Threshold for ON/OFF
Inpu
VOFF
Rseries = 22kΩ (Note 3)
ION/OFF
ON/OFF Input Current
1.4V ≤ VON/OFF ≤ 4.5V
1
12
5
µA
−0.3V ≤ VON/OFF ≤ 7V(Note 6)
−1
mA
Turn ON Threshold for Keep
Alive Input
ONK−A
OFFK−A
RP−D
2
V
V
Turn OFF Threshold for Keep
Alive Input
(Note 3)
0.8
40
Pull−Down Resistance at Keep
Alive Input
0V ≤ VK−A ≤ 5V
5
kΩ
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Electrical Characteristics (Continued)
Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. “Operating Ratings” indicate conditions for which the device is
functional, but do not guarantee specific performance limits. “Electrical Characteristics” state DC and AC electrical specifications under particular test conditions which
guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit
is given, however, the typical value is a good indication of device performance.
Note 2: Human body model, 150 pFcapacitor discharged through a 1.5 kΩ resistor.
Note 3: If either control input is left open circuited the regulators will turn OFF.
Note 4: The input quiescent current will increase when the regulators are in dropout conditions. The amount of additional input current is a direct function of the to
a load current on both outputs. The peak increase in current is limited to 50% of the total load current.
Note 5: The dropout voltage specifications actually indicate the saturation voltage of the PNP power transistors used in each regulator. Over the full load current and
temperature ranges the Main regulator will output at least 4.5V and the External Supply regulator at lease 4.7V with an input voltage of only 5.5V
Note 6: The ON/OFF input is internally clamped to a 7V zener diode through a 1KΩ resistor.
Quiescent Input Current vs. Input Voltage
Turn-On Characteristic
DS101296-5
DS101296-4
Turn-Off Characteristic
Normalized Output Voltages vs Temperature
DS101296-6
DS101296-7
5
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Electrical Characteristics (Continued)
Output Voltages at Input Voltage Extremes
Main Output Dropout Voltage vs Load Current
DS101296-9
DS101296-8
External Supply Output Short Circuit Current
Output Short Circuit Current vs Temperature
DS101296-10
DS101296-11
Watchdog and Reset Delay Time vs Temperature
Maximum Power Dissipation
DS101296-12
DS101296-13
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Electrical Characteristics (Continued)
Output Capacitor ESR
DS101296-14
7
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Electrical Characteristics (Continued)
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Control Logic Truth Table
ON/OFF Input Keep-Alive Input Main Output Voltage External Supply Output Reset Output
Voltage
Operating Condition
<
L
Rising Edge
H
L
L
X
0V
5V
5V
0V
5V
5V
0V
Rising after delay
5V
OFF, Input curent 100µA
Outputs turn ON, Power ON
delayed reset
Normal ON condition
Main output pulled out of
regulation,
<
4V or
<
<
H
X
4.5V or
5.35V
X
0V
Reset flag generated.
Threshold depends on Reset
Adjust seting (pin 11)
Keep-Alive, Continued normal
operation
Falling Edge
L
H
5V
5V
5V
5V
5V
Outputs turned ON by
Keep-Alive Input
Rising Edge
Rising after delay
use in a wide variety of automotive and industrial applica-
tions were precision supply regulation is required in harsh
operating environments. The following will describe the func-
tionality of each of the package pins.
Application Information
Pin Description and Functionality
The LM9073 is a precision dual voltage regulator optimized
for use in powertrain module applications but will also find
Figure 1. Circuit Block Diagram
DS101296-16
Input Voltage (pin 4)
The current drain on the supply line is directly proportional to
the load currents on the two voltage regulators. With no load
current on either output the regulator requires 15mA maxi-
mum quiescent current for biasing internal circuitry. During
The LM9073 has been designed to connect directly to the ig-
nition or battery supply in automotive applications. For this
type of supply the regulator been designed to withstand up to
+60V and −45V supply transients such as load dump. An ov-
ervoltage shut down protection circuit turns OFF both of the
regulator outputs should supply transients exceed typically
+33V to fully protect all load circuitry. This higher threshold
allows normal operation with 24VDC applied to the input as in
the event when two batteries are used to start a vehicle. Pro-
tection of the system is also provided for inadvertent reverse
polarity battery connections.
<
dropout conditions (VIN 5.5V) the additional input current
can rise to 50% of the total load current. With less than 3V
applied to the input, internal biasing circuitry shuts OFF.
When switched OFF the regulator can remain connected to
the battery supply with a current drain of less than 100µA.
Main Output (pin 10)
The Main Output regulator provides a well controlled (2% tol-
erance maximum) 5V supply line with a total load current
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External Supply Output (pin 5)
Application Information (Continued)
The External Supply Output regulator is a secondary 5V, 2%
tolerance regulated output of the LM9073. this 100mA output
is available to bias sensors and other devices located exter-
nal to the main system module.
ranging up to 700mA. This relatively high level of output cur-
rent is sufficient to provide power to a large number of load
circuits in a variety of module applications.
This output has a short to ground current limit between
900mA and 2A. It is not protected for shorts to battery how-
ever, but can withstand an output short to a potential of 7
Volts or less.
For providing remote power the External Supply Output is
fully protected against short circuit connections to the battery
or input supply (up to 27V) and to ground. These shorted
fault conditions do not effect the operation of the main supply
nor generate a reset of the system.
To maintain stability of this supply line an output bypass ca-
pacitor is required. This capacitor must be at least 6µF with
an equivalent series resistance (ESR) between 0.3Ω and 3Ω
over temperature.
Like the main output a bypass capacitor is required for stabil-
ity. This capacitor should be also greater than 6µF with an
ESR between 0.3Ω and 3Ω.
The Main Output is sensed for the generation of the system
reset output.
Figure 2. Reset Generator and Watchdog Circuitry
DS101296-17
Reset Output (pin 7)
switches OFF (sink current of only 500µA). At such a low
supply potential, system controllers are generally inopera-
tive.
The Reset Output is an active low logic signal provided to re-
set a system mircocontroller on power up and in the event
that the Main Output falls out of regulation. This output is
The Reset Output has a built-in delay time interval which is
programmable by the section of the delay capacitor.
<
guaranteed to provide a logic low level ( 0.4V) whenever
the Main Output supply is below a threshold set by the Reset
Adjust pin strap option (see Reset Adjust section) or is pulled
above 5.75V. This general reset prevents erratic system op-
eration which may occur with out-of-specification supply po-
tentials.
Reset Adjust (pin 11)
The low Vmain threshold voltage for generating a system re-
set can be shifted by 500mV through the use of a pin strap to
ground on pin 11. With this pin shorted to ground the thresh-
old is between 4.5V and 4.7V. With this pin left open the
threshold is shifted to between 4.0V and 4.2V. This lower
threshold allows the system to remain operational longer
during power down. The higher threshold ensures that the
system is reset when the nominal 5V supply is low by 10%,
which in some cases can produce uncertain microprocessor
operation.
The Reset Output has an active pull down which can sink up
to 15mA of current and a passive pull-up (through a 4KΩ re-
sistor) to the Main Output to ensure voltage compatibility
with the system supply. Capacitive loading on this reset line
will directly affect the rise time of the reset signal. The Reset
Output will maintain a logic low level with a Main Output volt-
age of only 1V. Below 1V the active pull-down device
Delay Capacitor (pin 8)
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comparators C1 and C2 detect if the Main Supply is below
4.6V (4.1V with Reset Adjust open circuited) or exceeds
5.5V typically. If this is true (at power−on for example) the
control logic turns ON the discharge transistor and holds
CDELAY low (at 0.9V). Comparator C4 then outputs a logic
low system Reset signal within 2µS after detecting the out of
regulation condition.
Application Information (Continued)
The Delay Capacitor (CDELAY) controls a time interval during
which the Reset Output remains low after the Main Output
has established normal operating condition. This feature
holds the system in reset for a time to allow all load circuitry
to properly bias before executing functions. This interval is
applied at power−up and following any event that may trigger
the system reset function.
Figure 2 illustrates the delayed reset generator. Two com-
parators continually monitor the Main Output supply. Window
Figure 3. Watchdog and Reset Operation
DS101296-18
The Delay Capacitor remains discharged until the window
comparator senses that the Main Output is within normal op-
erating range (C1 and C2 outputs are both low). When this
condition is met, the discharge transistor is turned OFF and
CDELAY is charged positively by an internal 6µA current
source. The Reset Output will remain low until the delay ca-
pacitor has reached 4V, at which point it will go high and the
system will begin normal operation. This delay time interval
is controlled by the section of CDELAY and can be determined
from the following equation:
approximately 50µA) then slowly charges positive with a
charging current of 6µA. If this capacitor ever charges up to
4V or more, a system reset is generated.
The watchdog time interval is set by the selection of Cwatch-
dog and can be found from the following equation:
TWD = (0.5 x 106) x Cwatchdog
The watchdog timer function can be disabled by grounding
pin 2 or replacing Cwatchdog by a resistor with a value less
than 22kΩ. With this only the reset generator can reset the
system.
TDELAY = (0.5 x 106) x CDELAY
Watchdog Trigger (pin 1)
A 0.1µF capacitor will produce a typical delay interval of
50mSec.
The Watchdog Trigger input accepts a pulse from the system
controller to refresh the watchdog capacitor and prevent it
from reaching 4V and resetting the system. This positive
pulse must be at least 10µS long and triggers an internal
one-shot pulse. This internal pulse latches ON Qdischarge
Watchdog (figure 2) and discharges Cwatchdog to 0.9V. This
latching action ensures a consistent watchdog timer interval
by not allowing the capacitor to charge positively until it has
been discharged to 0.9V.
To ensure a consistent delay time interval, the discharge
transistor is always latched ON by the window comparators,
and can not be switched OFF to start a new delay interval
until CDELAY has been discharged to less than or equal to
0.9V. This sets a fixed starting voltage (0.9V) and ending
voltage (4V) for the charging of the Delay Capacitor.
Watchdog Capacitor (pin 2)
The LM9073 also provides a simple system watchdog timer.
The watchdog timer requires the system controller to issue a
pulse at a regular interval (programmable through the selec-
tion of Cwatchdog) to provide an indication that the system is
properly executing controlling software code. The absence
of a pulse before the watchdog timer comes out could indi-
cate that the system is caught in a infinite loop and the sys-
tem is reset
As shown in Figure 3, each watchdog trigger input pulse re-
sets the timer capacitor. If the watchdog trigger signal does
not refresh the timer before Cwatchdog reaches 4V, a sys-
tem reset is generated. Once reset, a full reset delay interval
occurs. At the end of this interval the regulator will automati-
cally try to re-start the system by taking reset high. If the sys-
tem does not respond properly by issuing a watchdog trigger
signal in time, the system will once again reset. In this situa-
tion the reset output will continually cycle high (re-starting
the system) for the watchdog time interval and low
(re-setting the system) for the reset delay interval.
The watchdog capacitor is held discharged to ground at any
time that the system is reset. When the reset is released the
capacitor quickly charges to 0.9V (with a charging current of
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Keep-Alive Input (pin 9)
Application Information (Continued)
This CMOS logic level compatible input provides a system
with the ability to control it’s own ON/OFF sequencing. The
Keep-Alive Input is OR’ed with the ON/OFF Input so either
one can independently control the regulators.
A low to high transition is required during the watchdog timer
interval at the trigger input. If this line is ever fixed high the
timer will time-out and the system will reset.
ON/OFF Input (pin 3)
As shown in the Operational Characteristics, a system con-
troller can take the Keep-Alive Input high at any time. If the
ON/OFF switch is opened, this high level on Keep-Alive will
keep the regulators ON and the entire system operational.
This control is useful for providing as much time as neces-
sary for a system to perform ’housekeeping’ chores such as
programming EEPROM with system information prior to
turning itself OFF (by taking the Keep-Alive Input low) and
reverting to the low quiescent current state.
The ON/OFF Input enables both the Main and External Sup-
ply outputs. In a typical application this input is connected to
the input supply through a series resistor (nominally 22KΩ)
and a switch (Ignition, as an example).When the switch is
closed this input is pulled high and switches ON both regula-
tor outputs. This input is internally clamped to a 7V zener di-
ode through a series 1kΩ resistor. The external series resis-
tor together with an optional 0.1µF capacitor to ground
provide filtering and current limiting to withstand transients
that may appear on the input supply to maintain normal op-
eration of the system.
A second use of the Keep-Alive Input can be from other mod-
ules which need information from the module powered by
>
LM9073. A high CMOS logic level ( 1.25V) on this input will
The switching threshold of the ON/OFF comparator has 2
Volts of hysteresis to ensure noise free control of the system.
To turn the regulators ON this input must be taken above 4V.
To turn the system OFF the ON/OFF Input must be open cir-
cuited or pulled below 2 Volts.
power up the system as needed independent from the nor-
mal ON/OFF switch.
Figure 4. Remote ON/OFF Control
DS101296-19
System Keep-Alive Operation
Transistor Q1 is shown as a means to inform the controller
that the ON/OFF switch has been opened. This high level on
an input line tells the controller that the system has been
switched OFF. This indicates the start of the Keep-Alive in-
terval. The system can perform whatever actions required to
obtain the proper OFF state before actually powering down.
These general housekeeping tasks can include putting ex-
ternal devices in the proper OFF condition and storing vari-
ous system variables in EPROM for example. With the con-
troller in command of the Keep-Alive interval these tasks can
take whatever time necessary to complete.
Figure 5 illustrates the basic concept of Keep-Alive opera-
tion. The LM9073 provides the regulated supplies to an en-
tire microcontroller based system or module including re-
mote sensors. The system is switched ON or OFF by a
switch connected to the unregulated input supply and the
ON/OFF input, pin 3. When closed the regulators turn ON
and the system is held in a reset state for the duration of the
delayed reset interval controlled by CDELAY
.
Once normal operation of the system begins, the controller
needs to set an output line connected to the Keep-Alive in-
put, pin 9, high. The system remains in normal operation un-
til switched OFF by opening the ON/OFF switch. With
Keep-Alive high the entire system remains normally biased
and will remain operational until the Keep-Alive input is taken
low.
When completed the controller takes the Keep-Alive input to
a low level and the entire system shuts down. The LM9073
powers down to a low quiescent current mode with less than
100µA drawn from the input supply.
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Application Information (Continued)
Figure 5. Basic Keep-Alive Operation
DS101296-20
To initiate the Keep-Alive routine before actual power down,
it is important for the system controller to know when the sys-
tem has been switched OFF. To eliminate any interface be-
tween the controller and the ON/OFF switch and potentially
noisy unregulated input supply, and simple logic scheme
shown in Figure 6 can be used. With this circuitry the Reset
output form the LM9073 provides the ON/OFF sensing input
to the controller.
level prevents the Reset output from resetting the entire sys-
tem and also gates the Keep-Alive input signal to the
LM9073. The inverted Reset signal provides a logic 1 to the
Keep-Alive input of the LM9073.
The Main output will only drop out of regulation for a very
short time before the Keep-Alive input turns it back on.
The Reset output remains low for the delay time interval.
When it turns high the Main output switches OFF and back
ON again very quickly. This continues until the system con-
troller takes the Keep-Alive output line to a logic low level.
When switched OFF, the main regulator output will fall out of
regulation and generate a low logic level on the Reset out-
put. This input to the controller provides the switch OFF indi-
cation and initiates the Keep-Alive interval.
Control of the Keep-Alive duration is set by a logic 1 on the
Keep-Alive output line from the system controller. This high
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Application Information (Continued)
Figure 6. Simple Logic Configuration to Provide
ON/OFF Sensing
DS101296-21
Input Stability
the input. The drop in input current may create a positive in-
put voltage transient which may take the PNP out of satura-
tion. If the input voltage is held constant at the threshold
where the PNP is going in and out of saturation, an oscilla-
tion may be created.
Low dropout voltage regulators which utilize a PNP power
transistor usually exhibit a large increase in current when in
<
dropout (Vin 5.5V). This increase is caused by the satura-
tion characteristics (β reduction) of the PNP transistor. To
significantly minimize this increase in current the LM9073
detects when the PNP enters the saturation and reduces the
operating current.
This is only observed where a large series inductance is
present in the input supply line and when the rise and fall
time of the input supply is very slow. If the application and re-
moval of the input voltage changes at a rate greater than
500mV/mS it will move through the dropout region of the
regulator (Vin of 3V to 5.5V) too quickly for an oscillation to
be established.
This reduction in input current can create a stability problem
in applications with higher load current ( 200mA). where the
input voltage is applied through a long length of wire which in
effect add a significant amount of inductance in series with
>
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Application Information (Continued)
Figure 7. Input Bypassing
DS101296-22
In the event that an oscillation is present, input bypassing
can also help de-tune the resonance. Figure 7 illustrates two
input bypassing approaches. The straight forward addition of
a larger valued electrolitic capacitor could suffice. In this
case however, if reverse battery connections are possibility it
is necessary to add a series protection diode as shown to
prevent damaging the polarized input capacitor.
obtain operation over the highest possible load current and
input voltage ranges, care must be taken to control the oper-
ating temperature of the device. Thermal shutdown protec-
tion is built with a threshold above 150˚C Conventional heat
sinking techniques can be used with the TO-220 package.
When applying the TO-263 package on-board heat sinking is
important to prevent thermal shutdown. More copper foil
area under the tab of the device will directly reduce the oper-
ating junction temperature. Use of a double sided board with
vias between two planes of copper as shown in Figure 8 will
improve performance ad can optimize the PC board surface
area required.
An alternative input bypassing scheme is also shown. This
eliminates the use of polarized input capacitors and a series
protection diode. The values shown were derived empirically
in a representative typical application. Appropriate values for
any given application require experimentation.
Thermal Management
The LM9073 is packaged in both a TO-263 surface mount
power package and a narrow lead-pitch TO-220 package. To
Figure 8. Typical TO-263 PC Board Heatsinking
DS101296-23
15
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Application Information (Continued)
Figure 9. EMC Test Circuit
DS101296-24
Electro-Magnetic Compatibiltiy (EMC)
•
Test Method
Closed loop current probe
Systems utilizing the LM9073 will not experience loss of sup-
ply or false reset signals from the regulator when subjected
to high frequency interference from a standard Bulk Current
Injection test (ISO11452 Part 4 test method). The following
test conditions and configuration (Figure 9) can be used to
verify this performance:
In this test configuration the current injected in to either the
input pin or the tracking output pin is increased until a reset
output is generated. These two pins are the most critical as
they typically will connect to a module through long lengths
of wire most likely to pick up high frequency energy. Figure
10 illustrates examples of test results on the LM9073 with
both types of modulation.
•
•
•
•
•
•
•
Frequency Range
Modulation 1
1MHz to 400MHz
(no modulation)
These results are just examples as actual results in any
given application will depend on numerous external factors
such as component selection, pc board layout, etc. The cur-
rent power of the injected signal is expressed indB relative to
1mA (i.e. 40dBmA = 100mA)
Modulation 2
1kHz sine wave, 80% AM
1 second
Dwell Time
Frequency Steps
1MHz (from 1MHz to 10MHz)
2MHz (from 10MHz to 200MHz)
20MHz (from 200MHz to 400MHz)
Figure 10. Examples of BCI Test
BCI Susceptibility, Modulation 1 (CW)
BCI Susceptibility, Modulation 2 (CW)
(1kHz, 80% AM Modulation)
DS101296-25
DS101296-26
www.national.com
16
Physical Dimensions inches (millimeters) unless otherwise noted
Order Number LM9073S
NS Package Number TS11B
17
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
Order Number LM9073T
NS Package Number TA11B
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DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
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Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: support@nsc.com
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Response Group
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National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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