LM2984.PDF
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LM2984 Microprocessor Power Supply System
February 1995
LM2984 Microprocessor Power Supply System
General Description
The LM2984 positive voltage regulator features three inde-
pendent and tracking outputs capable of delivering the pow-
er for logic circuits, peripheral sensors and standby memory
in a typical microprocessor system. The LM2984 includes
circuitry which monitors both its own high-current output and
also an external
m
P. If any error conditions are sensed in
either, a reset error flag is set and maintained until the mal-
function terminates. Since these functions are included in
the same package with the three regulators, a great saving
in board space can be realized in the typical microprocessor
system. The LM2984 also features very low dropout volt-
ages on each of its three regulator outputs (0.6V at the rat-
ed output current). Furthermore, the quiescent current can
be reduced to 1 mA in the standby mode.
Designed also for vehicular applications, the LM2984 and
all regulated circuitry are protected from reverse battery in-
stallations or 2-battery jumps. Familiar regulator features
such as short circuit and thermal overload protection are
also provided. Fixed outputs of 5V are available in the plas-
tic TO-220 power package.
Features
Y
Three low dropout tracking regulators
Y
Output current in excess of 500 mA
Y
Fully specified for
b
40
§
Cto
a
125
§
C operation
Y
Low quiescent current standby regulator
Y
Microprocessor malfunction RESET flag
Y
Delayed RESET on power-up
Y
Accurate pretrimmed 5V outputs
Y
Reverse battery protection
Y
Overvoltage protection
Y
Reverse transient protection
Y
Short circuit protection
Y
Internal thermal overload protection
Y
ON/OFF switch for high current outputs
Y
P
a
Product Enhancement tested
Typical Application Circuit
C
OUT
must be at least 10
m
Fto
maintain stability. May be increased
without bound to maintain regulation
during transients. Locate as close as
possible to the regulator. This capac-
itor must be rated over the same op-
erating temperature range as the
regulator. The equivalent series re-
sistance (ESR) of this capacitor is
critical; see curve.
TL/H/11252±1
Order Number LM2984T
See NS Package Number TA11B
C
1995 National Semiconductor Corporation
TL/H/11252
RRD-B30M75/Printed in U. S. A.
Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage
Survival Voltage (
k
100 ms)
Internal Power Dissipation Internally Limited
Operating Temperature Range (T
A
)
b
40
§
Cto
a
125
§
C
Maximum Junction Temperature (Note 1)
150
§
C
60V
Storage Temperature Range
b
65
§
Cto
a
150
§
C
Lead Temperature (Soldering, 10 sec.)
230
§
C
Operational Voltage
26V
ESD Susceptability (Note 3)
2000V
Electrical Characteristics
V
IN
e
14V, I
OUT
e
5 mA, C
OUT
e
10
m
F, unless otherwise indicated. Boldface type refers to limits over the entire operating
temperature range,
b
40
§
C
s
T
A
s a
125
§
C, all other limits are for T
A
e
T
j
e
25
§
C (Note 6).
Parameter
Conditions
Typical
Limit
Units
(Note 2)
V
OUT
(Pin 11)
Output Voltage
5 mA
s
I
O
s
500 mA
5.00
4.85/4.75
V
min
6V
s
V
IN
s
26V
5.15/5.25
V
max
Line Regulation
9V
s
V
IN
s
16V
2
25/25
mV
max
7V
s
V
IN
s
26V
5
50/50
mV
max
Load Regulation
5 mA
s
I
OUT
s
500 mA
12
50/50
mV
max
Output Impedance
250 mA
dc
and 10 mA
rms
,
24
m
X
f
o
e
120 Hz
Quiescent Current
I
OUT
e
500 mA
38
100/100
mA
max
I
OUT
e
250 mA
14
50/50
mA
max
Output Noise Voltage
10 Hz±100 kHz, I
OUT
e
100 mA
100
m
V
Long Term Stability
20
mV/1000 hr
Ripple Rejection
f
o
e
120 Hz
70
60/50
dB
min
Dropout Voltage
I
OUT
e
500 mA
0.53
0.80/1.1
V
max
I
OUT
e
250 mA
0.28
0.50/0.70
V
max
Current Limit
0.92
0.75/0.60
A
min
Maximum Operational
Continuous DC
32
26/26
V
min
Input Voltage
Maximum Line Transient
V
OUT
s
6V, R
OUT
e
100
X
,T
s
100 ms
65
60/60
V
min
Reverse Polarity
V
OUT
t b
0.6V, R
OUT
e
100
X
b
30
b
15/
b
15
V
min
Input Voltage DC
Reverse Polarity Input
T
s
100 ms, R
OUT
e
100
X
b
55
b
35/
b
35
V
min
Voltage Transient
2
Electrical Characteristics
(Continued)
V
IN
e
14V, I
buf
e
5 mA, C
buf
e
10
m
F, unless otherwise indicated. Boldface type refers to limits over the entire operating
temperature range,
b
40
§
C
s
T
A
s a
125
§
C, all other limits are for T
A
e
T
j
e
25
§
C (Note 6).
Parameter
Conditions
Typical
Limit
Units
(Note 2)
V
buffer
(Pin 10)
Output Voltage
5 mA
s
I
O
s
100 mA
5.00
4.85/4.75
V
min
6V
s
V
IN
s
26V
5.15/5.25
V
max
Line Regulation
9V
s
V
IN
s
16V
2
25/25
mV
max
7V
s
V
IN
s
26V
5
50/50
mV
max
Load Regulation
5 mA
s
I
buf
s
100 mA
15
50/50
mV
max
Output Impedance
50 mA
dc
and 10 mA
rms
,
200
m
X
f
O
e
120 Hz
Quiescent Current
I
buf
e
100 mA
8.0
15/15
mA
max
Output Noise Voltage
10 Hz±100 kHz, I
OUT
e
100 mA
100
m
V
Long Term Stability
20
mV/1000 hr
Ripple Rejection
f
o
e
120 Hz
70
60/50
dB
min
Dropout Voltage
I
buf
e
100 mA
0.35
0.50/0.80
V
max
Current Limit
0.23
0.15/0.15
A
min
Maximum Operational
Continuous DC
32
26/26
V
min
Input Voltage
Maximum Line
V
buf
s
6V, R
buf
e
100
X
,
65
60/60
V
min
Transient
T
s
100 ms
Reverse Polarity
V
buf
t b
0.6V, R
buf
e
100
X
b
30
b
15/
b
15
V
min
Input Voltage DC
Reverse Polarity Input
T
s
100 ms, R
buf
e
100
X
b
55
b
35/
b
35
V
min
Voltage Transient
Electrical Characteristics
V
IN
e
14V, I
stby
e
1 mA, C
stby
e
10
m
F, unless otherwise indicated. Boldface type refers to limits over the entire operating
temperature range,
b
40
§
C
s
T
A
s
a
125
§
C, all other limits are for T
A
e
T
j
e
25
§
C (Note 6).
Parameter
Conditions
Typical
Limit
Units
(Note 2)
V
standby
(Pin 9)
Output Voltage
1 mA
s
I
O
s
7.5 mA
5.00
4.85/4.75
V
min
6V
s
V
IN
s
26V
5.15/5.25
V
max
Line Regulation
9V
s
V
IN
s
16V
2
25/25
mV
max
7V
s
V
IN
s
26V
5
50/50
mV
max
Load Regulation
0.5 mA
s
I
OUT
s
7.5 mA
6
50/50
mV
max
Output Impedance
5 mA
dc
and1mA
rms
,f
o
e
120 Hz
0.9
X
Quiescent Current
I
stby
e
7.5 mA
1.2
2.0/4.0
mA
max
I
stby
e
2 mA
0.9
1.5/4.0
mA
max
3
Electrical Characteristics
(Continued)
V
IN
e
14V, I
stby
e
1 mA, C
stby
e
10
m
F, unless otherwise indicated. Boldface type refers to limits over the entire operating
temperature range,
b
40
§
C
s
T
A
s a
125
§
C, all other limits are for T
A
e
T
j
e
25
§
C (Note 6).
Parameter
Conditions
Typical
Limit
Units
(Note 2)
V
standby
(Pin 9) (Continued)
Output Noise Voltage
10 Hz±100 kHz, I
stby
e
1 mA
100
m
V
Long Term Stability
20
mV/1000 hr
Ripple Rejection
f
o
e
120 Hz
70
60/50
dB
min
Dropout Voltage
I
stby
e
1 mA
0.26
0.50/0.60
V
max
I
stby
e
7.5 mA
0.38
0.60/0.70
V
max
Current Limit
15
12/12
mA
min
Maximum Operational
4.5V
s
V
stby
s
6V,
65
60/60
V
min
Input Voltage
R
stby
e
1000
X
Maximum Line
V
stby
s
6V, T
s
100 ms,
65
60/60
V
min
Transient
R
stby
e
1000
X
Reverse Polarity
V
stby
t b
0.6V,
b
30
b
15/
b
15
V
min
Input Voltage DC
R
stby
e
1000
X
Reverse Polarity Input
T
s
100 ms, R
stby
e
1000
X
b
55
b
35/
b
35
V
min
Voltage Transient
Electrical Characteristics
V
IN
e
14V, C
OUT
e
10
m
F, C
buf
e
10
m
F, C
stby
e
10
m
F, unless otherwise indicated. Boldface type refers to limits over the
entire operating temperature range,
b
40
§
C
s
T
A
s a
125
§
C, all other limits are for T
A
e
T
j
e
25
§
C (Note 6).
Parameter
Conditions
Typical
Limit
Units
(Note 2)
Tracking and Isolation
Tracking
I
OUT
s
500 mA, I
buf
e
5 mA,
g
30
g
100/
g
100
mV
max
V
OUT
±V
stby
I
stby
s
7.5 mA
Tracking
I
OUT
e
5 mA, I
buf
s
100 mA,
g
30
g
100/
g
100
mV
max
V
buf
±V
stby
I
stby
s
7.5 mA
Tracking
I
OUT
s
500 mA, I
buf
s
100 mA,
g
30
g
100/
g
100
mV
max
V
OUT
±V
buf
I
stby
e
1mA
Isolation*
R
OUT
e
1
X
,I
buf
s
100 mA
5.00
4.50/4.50
V
min
V
buf
from V
OUT
5.50/5.50
V
max
Isolation*
R
OUT
e
1
X
,I
stby
s
7.5 mA
5.00
4.50/4.50
V
min
V
stby
from V
OUT
5.50/5.50
V
max
Isolation*
R
buf
e
1
X
,I
OUT
s
500 mA
5.00
4.50/4.50
V
min
V
OUT
from V
buf
5.50/5.50
V
max
Isolation*
R
buf
e
1
X
,I
stby
s
7.5 mA
5.00
4.50/4.50
V
min
V
stby
from V
buf
5.50/5.50
V
max
*Isolation refers to the ability of the specified output to remain within the tested limits when the other output is shorted to ground.
4
Electrical Characteristics
(Continued)
V
IN
e
14V, I
OUT
e
5 mA, I
buf
e
5 mA, I
stby
e
5 mA, R
t
e
130 k
X
,C
t
e
0.33
m
F, C
mon
e
0.47
m
F, unless otherwise indicated,
Boldface type refers to limits over the entire operating temperature range,
b
40
§
C
s
T
A
s a
125
§
C, all other limits are for T
A
e
T
J
e
25
§
C (Note 6)
Parameter
Conditions
Typical
Limit
Units
(Note 2)
Computer Monitor/Reset Functions
I
reset
Low
V
IN
e
4V, V
rst
e
0.4V
5
2/0.50
mA
min
V
reset
Low
V
IN
e
4V, I
rst
e
1 mA
0.10
0.40/0.40
V
max
R
t voltage
(Pin 2)
1.22
1.15/0.75
V
min
1.22
1.30/2.00
V
max
Power On Reset
V
m
P
mon
e
5V
50
45/17.0
ms
min
Delay
(T
dly
e
1.2 R
t
C
t
)
50
55/80.0
ms
max
D
V
OUT
Low
(Note 4)
b
350
b
225/
b
175
mV
min
Reset Threshold
b
500/
b
550
mV
max
D
V
OUT
High
(Note 4)
600
225/175
mV
min
Reset Threshold
750/800
mV
max
Reset Output
V
m
P
mon
e
5V, V
rst
e
12V
0.01
1/5.0
m
A
max
Leakage
m
P
mon
Input
V
m
P
mon
e
2.4V
7.5
25/25
m
A
max
Current (Pin 4)
V
m
P
mon
e
0.4V
0.01
10/15
m
A
max
m
P
mon
Input
1.22
0.80/0.80
V
min
Threshold Voltage
1.22
2.00/2.00
V
max
m
P Monitor Reset
V
m
P
mon
e
0V
50
45/30
ms
min
Oscillator Period
(T
window
e
0.82 R
t
C
mon
)
50
55/70
ms
max
m
P Monitor Reset
V
m
P
mon
e
0V
1.0
0.7/0.4
ms
min
Oscillator Pulse Width
(RESET
pw
e
2000 C
mon
)
1.0
1.3/2.10
ms
max
Minimum
m
P Monitor
(Note 5)
2
m
s
Input Pulse Width
Reset Fall Time
R
rst
e
10k, V
rst
e
5V, C
rst
s
10 pF
0.20
1.00/1.00
m
s
max
Reset Rise Time
R
rst
e
10k, V
rst
e
5V, C
rst
s
10 pF
0.60
1.00/1.50
m
s
max
On/Off Switch Input
V
ON
e
2.4V
7.5
25/25
m
A
max
Current (Pin 8)
V
ON
e
0.4V
0.01
10/10
m
A
max
On/Off Switch Input
1.22
0.80/0.80
V
min
Threshold Voltage
1.22
2.00/2.00
V
max
Note 1: Thermal resistance without a heatsink for junction-to-case temperature is 3
§
C/W. Thermal resistance case-to-ambient is 40
§
C/W.
Note 2: Tested Limits are guaranteed and 100% production tested.
Note 3: Human body model, 100 pF capacitor discharged through a 1500
X
resistor.
Note 4: Internal comparators detect when the main regulator output (V
OUT
) changes from the measured output voltage (with V
IN
e
14V) by the specified amount,
D
V
OUT
High or
D
V
OUT
Low, and set the Reset Error Flag low. The Reset Error Flag is held low until V
OUT
returns to regulation. The Reset Error Flag is then
allowed to go high again after a delay set by R
t
and C
t
. (see application section).
Note 5: This parameter is a measure of how short a pulse can be detected at the
m
P Monitor Input. This parameter is primarily influenced by the value of C
mon
.
(See Application Hints Section.)
Note 6: To ensure constant junction temperature, low duty cycle pulse testing is used.
5
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