MC3425 [ONSEMI]
POWER SUPPLY SUPERVISORY/ OVER AND UNDERVOLTAGE PROTECTION CIRCUIT; 电源监控/过压和欠压保护电路
| 型号： | MC3425 |
| 厂家： | 
ONSEMI |
| 描述： | POWER SUPPLY SUPERVISORY/ OVER AND UNDERVOLTAGE PROTECTION CIRCUIT |
| 文件： | 总12页 (文件大小：174K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Order this document by MC3425/D
POWER SUPPLY SUPERVISORY/
OVER AND UNDERVOLTAGE
PROTECTION CIRCUIT
The MC3425 is a power supply supervisory circuit containing all the
necessary functions required to monitor over and undervoltage fault
conditions. These integrated circuits contain dedicated over and
undervoltage sensing channels with independently programmable time
delays. The overvoltage channel has a high current Drive Output for use in
conjunction with an external SCR Crowbar for shutdown. The undervoltage
channel input comparator has hysteresis which is externally programmable,
and an open–collector output for fault indication.
SEMICONDUCTOR
TECHNICAL DATA
• Dedicated Over and Undervoltage Sensing
• Programmable Hysteresis of Undervoltage Comparator
• Internal 2.5 V Reference
• 300 mA Overvoltage Drive Output
• 30 mA Undervoltage Indicator Output
• Programmable Time Delays
8
1
P1 SUFFIX
PLASTIC PACKAGE
CASE 626
• 4.5 V to 40 V Operation
MAXIMUM RATINGS
Rating
Power Supply Voltage
Symbol
Value
40
Unit
Vdc
Vdc
mA
V
CC
Comparator Input Voltage Range (Note 1)
Drive Output Short Circuit Current
V
IR
–0.3 to +40
I
Internally
Limited
OS(DRV)
Indicator Output Voltage
V
0 to 40
30
Vdc
mA
IND
Indicator Output Sink Current
I
IND
PIN CONNECTIONS
Power Dissipation and Thermal Characteristics
Maximum Power Dissipation @ T = 70°C
P
1000
80
mW
°C/W
A
D
Thermal Resistance, Junction–to–Air
Operating Junction Temperature
Operating Ambient Temperature Range
Storage Temperature Range
R
θJA
T
+150
°C
°C
°C
O.V. DRV
Output
J
1
8
V
CC
T
A
0 to +70
O.V. DLY
2
3
4
7
6
5
Gnd
T
stg
–55 to +150
U.V. IND
Output
NOTE: 1. The input signal voltage should not be allowed to go negative by more than 300 mV
O.V. Sense
U.V. Sense
NOTE: 1. or positive by more than 40 V, independent of V , without device destruction.
CC
U.V. DLY
Simplified Application
(Top View)
Overvoltage Crowbar Protection, Undervoltage Indication
V
V
out
in
DC
Power
Supply
MC3425
+
Undervoltage
Indication
ORDERING INFORMATION
Operating
C
out
Temperature Range
Device
Package
MC3425P1
T
A
= 0° to +70°C
Plastic DIP
Motorola, Inc. 1996
Rev 2
MC3425
ELECTRICAL CHARACTERISTICS (4.5 V ≤ V
≤ 40 V; T = T
to T
[Note 2], unless otherwise noted.)
CC
A
low
high
Characteristics
Symbol
Min
Typ
Max
Unit
REFERENCE SECTION
Sense Trip Voltage (Referenced Voltage)
V
Vdc
Sense
V
= 15 V
CC
T = 25°C
T
2.4
2.33
2.5
2.5
2.6
2.63
A
to T
(Note 2)
low
high
Line Regulation of V
Reg
line
–
7.0
15
40
mV
Sense
≤ 40 V; T = 25°C
4.5 V ≤ V
CC
J
Power Supply Voltage Operating Range
V
CC
4.5
–
Vdc
Power Supply Current
V
= 40 V; T = 25°C; No Output Loads
A
CC
O.V. Sense (Pin 3) = 0 V;
U.V. Sense (Pin 4) = V
I
I
–
–
8.5
10
19
mA
mA
CC(off)
CC
O.V. Sense (Pin 3) = V
CC
U.V. Sense (Pin 4) = 0 V
;
16.5
CC(on)
INPUT SECTION
Input Bias Current, O.V. and U.V. Sense
I
IB
–
1.0
2.0
µA
Hysteresis Activation Voltage, U.V. Sense
V
V
H(act)
V
= 15 V; T = 25°C;
= 10%
= 90%
CC
I
I
A
–
–
0.6
0.8
–
–
H
H
Hysteresis Current, U.V. Sense
= 15 V; T = 25°C; U.V. Sense (Pin 4) = 2.5 V
I
H
9.0
12.5
16
µA
V
CC
A
Delay Pin Voltage (I
Low State
High State
= 0 mA)
V
DLY
V
V
–
0.2
0.5
–
OL(DLY)
OH(DLY)
V
CC
–0.5
V
–0.15
CC
Delay Pin Source Current
= 15 V; V = 0 V
I
140
200
3.0
260
µA
DLY(source)
V
CC
Delay Pin Sink Current
= 15 V; V = 2.5V
DLY
I
1.8
–
mA
DLY(sink)
V
CC
DLY
OUTPUT SECTION
Drive Output Peak Current (T = 25°C)
I
200
300
–
–
mA
V
A
DRV(peak)
Drive Output Voltage
V
V
CC
–2.5
V
–2.0
OH(DRV)
CC
I
= 100 mA; T = 25° C
DRV
Drive Output Leakage Current
= 0 V
A
I
–
15
200
nA
DRV(leak)
V
DRV
Drive Output Current Slew Rate (T = 25°C)
di/dt
–
–
2.0
1.0
–
–
A/µs
A
Drive Output V
Transient Rejection
I
mA
(Peak)
CC
= 0 V to 15 V at dV/dt = 200 V µs;
DRV(trans)
V
CC
O.V. Sense (Pin 3) = 0 V; T = 25°C
A
Indicator Output Saturation Voltage
V
–
–
560
25
800
200
2.63
mV
nA
V
IND(sat)
I
= 30 mA; T = 25°C
IND
Indicator Output Leakage Current
= 40 V
A
I
IND(leak)
V
OH(IND)
Output Comparator Threshold Voltage (Note 3)
V
2.33
2.5
th(OC)
Propagation Delay Time
(V
CC
= 15 V; T = 25°C)
A
Input to Drive Output or Indicator Output
t
–
–
1.7
–
–
µs
PLH(IN/OUT)
100 mV Overdrive, C
= 0 µF
DLY
Input to Delay
2.5 V Overdrive (0 V to 5.0 V Step)
t
700
ns
PLH(IN//DLY)
NOTES: 2. T
low
to T
= 0° to +70°C
limits are approximately the V
high
3. The V
limits over the applicable temperature range.
Sense
th(OC)
2
MOTOROLA ANALOG IC DEVICE DATA
MC3425
Figure 1. Hysteresis Current versus
Hysteresis Activation Voltage
Figure 2. Hysteresis Activation Voltage
versus Temperature
1.2
14
12
V
= Voltage Level at
H(act)
which Hysteresis Current
(I ) is 90% of full value.
T
= 25
°
C
A
V
= 5.0 V
1.0
0.8
0.6
CC
H
10
V
= 15 V
CC
8.0
V
= 40 V
CC
V
= 40 V
CC
6.0
4.0
2.0
0
V
CC
0.4
0.2
0
= 15 V
V
= 5.0 V
1.0
CC
0
0.2
0.4
0.6
0.8
1.2
1.4
1.6
–55
–25
0
25
50
75
C)
100
125
V
, HYSTERESIS ACTIVATION VOLTAGE (V)
T
AMBIENT TEMPERATURE (
°
H(act)
A,
Figure 3. Hysteresis Current
versus Temperature
Figure 4. Sense Trip Voltage Change
versus Temperature
15.0
14.0
13.0
12.0
11.0
10.0
V
* = 2.400 V
* = 2.500 V
* = 2.600 V
Sense
0
–10
–20
–30
–40
–50
U.V. Sense = 2.5 V
V
= 15 V
CC
*V
at T = 25°C
Sense
A
–55
–25
0
25
50
75
C)
100
125
–55
–25
0
25
50
75
C)
100
125
T , AMBIENT TEMPERATURE (
°
T , AMBIENT TEMPERATURE (
°
A
A
Figure 5. Output Delay Time versus
Delay Capacitance
Figure 6. Delay Pin Source Current
versus Temperature
260
240
220
200
180
160
100
V
= 15 V
CC
= 25°C
T
A
10
1.0
0.1
V
= 40 V
= 15 V
CC
V
CC
2.5 C
200
DLY
t
=
DLY
µA
V
= 5.0 V
CC
0.01
0.001
0.0001
0.001
0.01
0.1
1.0
10
–55
–25
0
25
50
75
C)
100
125
C
, DELAY PIN CAPACITANCE (
µ
F)
T , AMBIENT TEMPERATURE (
°
DLY
A
3
MOTOROLA ANALOG IC DEVICE DATA
MC3425
Figure 7. Drive Output Saturation Voltage
versus Output Peak Current
Figure 8. Indicator Output Saturation Voltage
versus Output Sink Current
5.0
4.0
3.0
2.0
1.0
0
0.4
0.3
V
= 15 V
CC
1.0% Duty Cycle @ 300 Hz
= 25
T
°C
A
0.2
0.1
V
= 15 V
= 25°C
CC
T
A
0
0
100
200
300
400
0
10
20
30
40
I
, DRIVE OUTPUT PEAK CURRENT (mA)
I
, INDICATOR OUTPUT SINK CURRENT (mA)
DRV(peak)
IND
Figure 9. Drive Output Saturation Voltage
versus Temperature
Figure 10. Power Supply Current
versus Voltage
2.500
2.460
2.420
2.380
2.340
2.300
28
24
20
16
12
8.0
4.0
0
Curve O.V. Sense U.V. Sense
V
I
= 15 V
CC
A
B
V
Gnd
= 200 mA
CC
Gnd
DRV(peak)
1.0% Duty Cycle @ 300 Hz
V
CC
A
B
T
= 25°C
A
0
5.0
10
15
, POWER SUPPLY VOLTAGE (V)
CC
20
25
30
35
40
–55
–25
0
25
50
75
C)
100
125
V
T , AMBIENT TEMPERATURE (
°
A
4
MOTOROLA ANALOG IC DEVICE DATA
MC3425
APPLICATIONS INFORMATION
Figure 11. Overvoltage Protection and
Undervoltage Fault Indication with
Programmable Delay
Figure 12. Overvoltage Protection of 5.0 V
Supply with Line Loss Detector
V
V
= 5.0 V
O
+V
O
+5.0V
Power
Supply
= 6.25 V
V
O(trip)
in
8
1.0k
V
CC
15k
R1A
R1B
4
3
6
1
Line Loss
Output
U.V.
Sense
U.V.
IND
8
V
AC Line
+
CC
U.V. Fault
Indicator
MC3425
Power
Supply
4.5V to 40V
–
4
6
1
U.V.
Sense
U.V.
IND
O.V.
Sense
O.V.
DRV
I
H
MC3425
10k
O.V.
DLY
U.V.
DLY
3
O.V.
Sense
O.V.
DRV
Gnd
2
7
5
100
U.V.
DLY
O.V.
DLY
2
0.33µF
0.01
µ
F
Gnd
7
5
R2A
R2B
U.V. Sense
Pin 4
C
C
DLY
DLY
Gnd
2.5V
2.5V
U.V. DLY
Pin 5
R1B R2B
R1B + R2B
R1A
R2A
U.V. Hysteresis = I
, V
– 2.5 V 1 +
O(trip)
H
U.V. IND
Pin 6
OFF
ON
t
= 12500 C
DLY
DLY
Figure 13. Overvoltage Audio Alarm Circuit
Figure 14. Programmable Frequency Switch
12V
8
Input Signal 5.0
µF
+V
O
Output Pulse when:
8
V
CC
I.V. p–p
12k
Alarm On when:
1
V
10k
CC
f
<
(input)
V
= 13.6 V
25000 C
O
DLY
3
4
1
O.V.
DRV
O.V.
Sense
O.V.
Sense
O.V.
DRV
3
4
1
+
1.0k
10k
MC3425
2.7k
MC3425
12V
Power
Supply
U.V.
Sense
U.V.
100Ω
U.V.
Sense
O.V.
DLY
82k
DLY
Gnd
7
U.V. O.V.
DLY DLY
Gnd
7
5
F
2
5
2
6.8k
C
0.1
µ
DLY
0.1µF
Gnd
O.V. Sense
Pin 3
2.5V
O.V. DLY
Pin 2
2.5V
ON
O.V. DRV
Pin 1
OFF
5
MOTOROLA ANALOG IC DEVICE DATA
MC3425
CIRCUIT DESCRIPTION
The MC3425 is a power supply supervisory circuit
containing all the necessary functions required to monitor
over and undervoltage fault conditions. The block diagram
is shown below in Figure 15. The Overvoltage (O.V.) and
Undervoltage (U.V.) Input Comparators are both
referenced to an internal 2.5 V regulator. The U.V. Input
Comparator has a feedback activated 12.5 µA current sink
source, I
, charging the external delay capacitor
DLY(source)
(C
) to 2.5 V.
DLY
V
C
2.5 C
DLY
ref DLY
= 12500 C
t
=
=
DLY
DLY
I
200 µA
DLY(source)
Figure 5 provides C
delays. The Delay pins are pulled low when the respective
input comparator’s noninverting input is less than the
values for a wide range of time
(I ) which is used for programming the input hysteresis
DLY
H
voltage (V ). The source resistance feeding this input (R )
H
H
H H
determines the amount of hysteresis voltage by V = I R
H
–6
= 12.5 × 10 R .
inverting input. The sink current, I
, capability of the
DLY(sink)
H
Delay pins is ≥ 1.8 mA and is much greater than the typical
200 µA source current, thus enabling a relatively fast delay
capacitor discharge time.
Separate Delay pins (O.V. DLY, U.V. DLY.) are provided for
each channel to independently delay the Drive and Indicator
outputs, thus providing greater input noise immunity. The two
Delay pins are essentially the outputs of the respective input
comparators, and provide a constant current source,
The Overvoltage Drive Output is a current–limited
emitter–follower capable of sourcing 300 mA at a turn–on
slew rate at 2.0 A/µs, ideal for driving “Crowbar” SCR’s. The
Undervoltage Indicator Output is an open–collector, NPN
transistor, capable of sinking 30 mA to provide sufficient drive
for LED’s, small relays or shut–down circuitry. These current
capabilities apply to both channels operating simultaneously,
providing device power dissipation limits are not exceeded.
The MC3425 has an internal 2.5 V bandgap reference
regulator with an accuracy of ± 4.0% for the basic device.
I
, of typically 200 µA when the noninverting input
DLY(source)
voltage is greater than the inverting input level. A capacitor
connected from these Delay pins to ground, will establish a
predictable delay time (t
) for the Drive and Indicator
DLY
outputs. The Delay pins are internally connected to the
noninverting inputs of the O.V. and U.V. Output Comparators,
which are referenced to the internal 2.5 V regulator.
Therefore, delay time (t
) is based on the constant current
DLY
Figure 15. Representative Block Diagram
V
CC
8
+
+
O.V.
Sense
200µA
+
+
+
Input
Comparator
Output
Comparator
O.V.
3
–
O.V.
–
O.V.
DRV
1
6
+
–
U.V.
IND
Output
Comparator
200
µA
+
U.V.
Input
+
U.V.
Sense
Comparator
U.V.
+
–
4
2.5V
Reference
Regulator
I
H
12.5µA
5
2
7
Gnd
Output Section
Input Section
U.V. O.V.
DLY DLY
Note: All voltages and currents are nominal.
6
MOTOROLA ANALOG IC DEVICE DATA
MC3425
CROWBAR SCR CONSIDERATIONS
Referring to Figure 16, it can be seen that the crowbar
SCR, when activated, is subject to a large current surge from
current flows through this turned–on gate region, very high
current densities can occur in the gate region if high anode
currents appear quickly (di/dt). This can result in immediate
destruction of the SCR or gradual degradation of its forward
blocking voltage capabilities – depending on the severity of
the occasion.
The value of di/dt that an SCR can safely handle is
influenced by its construction and the characteristics of the
gate drive signal. A center–gate–fire SCR has more di/dt
capability than a corner–gate–fire type, and heavily
the output capacitance, C . This capacitance consists of
out
the power supply output capacitors, the load’s decoupling
capacitors, and in the case of Figure 16A, the supply’s input
filter capacitors. This surge current is illustrated in Figure 17,
and can cause SCR failure or degradation by any one of
2
three mechanisms: di/dt, absolute peak surge, or I t. The
interrelationship of these failure methods and the breadth of
the applications make specification of the SCR by the
semiconductor manufacturer difficult and expensive.
Therefore, the designer must empirically determine the SCR
and circuit elements which result in reliable and effective OVP
operation. However, an understanding of the factors which
influence the SCR’s di/dt and surge capabilities simplifies
this task.
overdriving ( 3 to 5 times I ) the SCR gate with a fast < 1.0
GT
µs rise time signal will maximize its di/dt capability. A typical
maximum number in phase control SCRs of less than 50
A(RMS) rating might be 200 A/µs, assuming a gate current of
five times I
and < 1.0 µs rise time. If having done this, a di/dt
GT
problem is seen to still exist, the designer can also decrease
the di/dt of the current waveform by adding inductance in
series with the SCR, as shown in Figure 18. Of course, this
reduces the circuit’s ability to rapidly reduce the dc bus
voltage and a tradeoff must be made between speedy
voltage reduction and di/dt.
1. di/dt
As the gate region of the SCR is driven on, its area of
conduction takes a finite amount of time to grow, starting as a
very small region and gradually spreading. Since the anode
Figure 16. Typical Crowbar Circuit Configurations
(A) SCR Across Input of Regulator
Series
Regulator
V
V
out
in
MC3425
+
+
C
C
out
in
(B) SCR Across Output of Regulator
*
Series
Regulator
V
V
out
in
+
+
C
C
out
in
MC3425
*Needed if supply is not current limited.
7
MOTOROLA ANALOG IC DEVICE DATA
MC3425
Figure 17. Crowbar SCR Surge Current Waveform
A WORD ABOUT FUSING
Before leaving the subject of the crowbar SCR, a few
words about fuse protection are in order. Referring back to
Figure 16A, it will be seen that a fuse is necessary if the
power supply to be protected is not output current limited.
This fuse is not meant to prevent SCR failure but rather to
prevent a fire!
l
l
pk
di
dt
Surge Due to
Output Capacitor
In order to protect the SCR, the fuse would have to
2
possess an I t rating less than that of the SCR and yet have
a high enough continuous current rating to survive normal
supply output currents. In addition, it must be capable of
successfully clearing the high short circuit currents from the
supply. Such a fuse as this is quite expensive, and may not
even be available.
Current Limited
Supply Output
t
The usual design compromise then is to use a garden
variety fuse (3AG or 3AB style) which cannot be relied on to
blow before the thyristor does, and trust that if the SCR does
fail, it will fail short circuit. In the majority of the designs, this
will be the case, though this is difficult to guarantee. Of
course, a sufficiently high surge will cause an open. These
comments also apply to the fuse in Figure 16B.
2. Surge Current
If the peak current and/or the duration of the surge is
excessive, immediate destruction due to device overheating
will result. The surge capability of the SCR is directly
proportional to its die area. If the surge current cannot be
reduced (by adding series resistance – see Figure 18) to a
safe level which is consistent with the system’s requirements
for speedy bus voltage reduction, the designer must use a
higher current SCR. This may result in the average current
capability of the SCR exceeding the steady state current
requirements imposed by the DC power supply.
CROWBAR SCR SELECTION GUIDE
As an aid in selecting an SCR for crowbar use, the
following selection guide is presented.
Figure 18. Circuit Elements Affecting
SCR Surge & di/dt
Device
I
I
TSM
RMS
MCR310 Series
MCR16 Series
MCR25 Series
2N6501 Series
MCR69 Series
MCR264 Series
MCR265 Series
10 A
16 A
25 A
25 A
25 A
40 A
55 A
100 A
150 A
300 A
300 A
750 A
400 A
550 A
R
L
Lead
Lead
R
ESR
ESL
Output
Cap
L
To
MC3423
R & L EMPIRICALLY DETERMINED!
UNDERVOLTAGE SENSING
An undervoltage sense circuit with hysteresis may be
designed, as shown in Figure 11, using the following
equations:
V
V
CCU
12.5
CC1
R1
R2
A
2.5 R1
V
2.5
CC1
where:
V
is the designed upper trip point
CCU
(output indicator goes off)
is the lower trip point
V
CC1
(output indicator goes on)
8
MOTOROLA ANALOG IC DEVICE DATA
MC3425
OUTLINE DIMENSIONS
P1 SUFFIX
PLASTIC PACKAGE
CASE 626–05
ISSUE K
8
5
NOTES:
1. DIMENSION L TO CENTER OF LEAD WHEN
–B–
FORMED PARALLEL.
1
4
2. PACKAGE CONTOUR OPTIONAL (ROUND OR
SQUARE CORNERS).
3. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
F
MILLIMETERS
INCHES
–A–
NOTE 2
DIM
A
B
C
D
F
MIN
9.40
6.10
3.94
0.38
1.02
MAX
10.16
6.60
4.45
0.51
1.78
MIN
MAX
0.400
0.260
0.175
0.020
0.070
L
0.370
0.240
0.155
0.015
0.040
C
G
H
J
K
L
2.54 BSC
0.100 BSC
0.76
0.20
2.92
1.27
0.30
3.43
0.030
0.008
0.115
0.050
0.012
0.135
J
–T–
SEATING
N
7.62 BSC
0.300 BSC
PLANE
M
M
N
–––
0.76
10
1.01
–––
0.030
10
0.040
D
K
G
H
M
M
M
0.13 (0.005)
T
A
B
9
MOTOROLA ANALOG IC DEVICE DATA
MC3425
NOTES
10
MOTOROLA ANALOG IC DEVICE DATA
MC3425
NOTES
11
MOTOROLA ANALOG IC DEVICE DATA
MC3425
Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding
the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and
specificallydisclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be provided in Motorola
datasheetsand/orspecificationscananddovaryindifferentapplicationsandactualperformancemayvaryovertime. Alloperatingparameters,including“Typicals”
must be validated for each customer application by customer’s technical experts. Motorola does not convey any license under its patent rights nor the rights of
others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other
applicationsintended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury
ordeathmayoccur. ShouldBuyerpurchaseoruseMotorolaproductsforanysuchunintendedorunauthorizedapplication,BuyershallindemnifyandholdMotorola
and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees
arisingoutof,directlyorindirectly,anyclaimofpersonalinjuryordeathassociatedwithsuchunintendedorunauthorizeduse,evenifsuchclaimallegesthatMotorola
was negligent regarding the design or manufacture of the part. Motorola and
Opportunity/Affirmative Action Employer.
re registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal
How to reach us:
USA/EUROPE/Locations Not Listed: Motorola Literature Distribution;
P.O. Box 20912; Phoenix, Arizona 85036. 1–800–441–2447 or 602–303–5454
JAPAN: Nippon Motorola Ltd.; Tatsumi–SPD–JLDC, 6F Seibu–Butsuryu–Center,
3–14–2 Tatsumi Koto–Ku, Tokyo 135, Japan. 03–81–3521–8315
MFAX: RMFAX0@email.sps.mot.com – TOUCHTONE 602–244–6609
INTERNET: http://Design–NET.com
ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping Industrial Park,
51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852–26629298
M3425/D
◊
相关型号：
©2020 ICPDF网 联系我们和版权申明