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Электронный компонент: L4964HT

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L4964
April 1993
HIGH CURRENT SWITCHING REGULATOR
.
4 A OUTPUT CURRENT
.
5.1 V TO 28 V OUTPUT VOLTAGE RANGE
.
0 TO 100 % DUTY CYCLE RANGE
.
PRECISE (
3 %) ON-CHIP REFERENCE
.
SWITCHING FREQUENCY UP TO 120 KHz
.
VERY HIGH EFFICIENCY (UP TO 90 %)
.
VERY FEW EXTERNAL COMPONENTS
.
SOFT START
.
RESET OUTPUT
.
CURRENT LIMITING
.
INPUT FOR REMOTE INHIBIT AND SYN-
CHRONUS PWM
.
THERMAL SHUTDOWN
DESCRIPTION
The L4964 is a stepdown power switching regulator
delivering 4A at a voltage variable from 5.1V to 28V.
Features of the device include overload protection,
soft start, remote inhibit, thermal protection, a reset
output for microprocessors and a PWM comparator
input for synchronization in multichip configurations.
The L4964 is mounted in a 15-lead Multiwatt
plas-
tic power package and requires very few external
components.
Efficient operation at switching frequencies up to
120kHz allows a reduction in the size and cost of ex-
ternal filter components.
MUL TIW AT T15 Verti cal
(Plastic Package)
ORDERING NUMBER : L4964
MULTI WATT15 Horizo ntal
(Plastic Package)
ORDERING NUMBER : L4964HT
Pins 1, 4, 15 must not be connected. Leave open circuit.
PIN CONNECTION (top view)
1/13
PIN FUNCTIONS
N
Name
Function
1
N.C.
Must not be connected. Leave open circuit.
2
Output
Regulator Output.
3
Supply Voltage
Unregulated Voltage Input. An internal regulator powers the L4964's internal logic.
4
N.C.
Must not be connected. Leave open circuit.
5
Soft Start
Soft Start Time Constant. A capacitor is connected between this terminal and ground
to define the soft start time constant. This capacitor also determines the average short
circuit output current.
6
Inhibit Input
TTL - Level Remote Inhibit. A logic high level on this input disables the L4964.
7
Sync Input
Multiple L4964's are synchronized by connecting the pin 7 inputs together and omitting
the oscillator RC network on all but one device.
8
Ground
Common Ground Terminal.
9
Frequency
Compensation
A series RC network connected between this terminal and ground determines the
regulation loop gain characteristics.
10
Feedback
Input
The Feedback Terminal of the Regulation Loop. The output is connected directly to
this terminal for 5.1 V operation ; it is connected via a divider for higher voltages.
11
Oscillator
A parallel RC network connected to this terminal determines the switching frequency.
The pin must be connected to pin 7 input when the internal oscillator is used.
12
Reset Input
Input of the Reset Circuit. The threshold is roughly 5 V. It may be connected to the
beedback point or via a divider to the input.
13
Reset Delay
A capacitor connected between this terminal and ground determines the reset signal
delay time.
14
Reset Output
Open Collector Reset Signal Output. This output is high when the supply is safe.
15
N.C.
Must not be connected. Leave open circuit.
BLOCK DIAGRAM
L4964
2/13
CIRCUIT OPERATION (refer to the block diagram)
The L4964 is a monolithic stepdown switching regu-
lator providing output voltages from 5.1 V to 28 V
and delivering 4A.
The regulation loop consists of asawtooth oscillator,
error amplifier, comparator and the output stage. An
error signal is produced by comparing the output
voltage with a precise 5.1 V on-chip reference
(zener zap trimmed to
3 %). This error signal is
then compared with the sawtooth signal to generate
the fixed frequency pulse width modulated pulses
which drive the output stage. The gain and fre-
quency stability of the loop can be ajusted by an ex-
ternal RC network connected to pin 9. Closing the
loop directly gives an output voltage of 5.1 V. Higher
voltages are obtained by inserting a voltage divider.
Output overcurrents at switch on are prevented by
the soft start function. The error amplifier output is
initially clamped by the external capacitor C
ss
and al-
lowed to rise, linearly, as this capacitor is charged
by a constant current source.
Output overload protection is provided in the form of
a current limiter. The load current is sensed by an
internal metal resistor connected to a comparator.
When the load current exceeds a preset threshold
this comparator sets a flip flop which disables the
output stage and discharges the soft start capacitor.
A second comparator resets the flip flop when the
voltage across the soft start capacitor has fallen to
0.4 V. The output stage is thus re-enable and the
outputvoltage rises undercontro of the soft startnet-
work. If the overload condition is still present the
limiter will trigger again when the thershold current
is reached. The average short circuit current is lim-
ited to a safe value by the dead time introduced by
the soft start network.
The reset circuit generates an output signal when
the supply voltage exceeds a threshold pro-
grammed by an external divider. The reset signal is
generated with a delay time programmed by an ex-
ternal capacitor. When the supply falls below the
threshold the reset output goes low immediately.
The reset output is an open collector.
A TTL - level input is provided for applications such
as remote on/off control. This input is activated by
high level and disables circuit operation. After an in-
hibit the L4964 restarts under control of the soft start
network.
The thermal overload circuit disables circuit opera-
tion when the junction temperature reaches about
150 and has hysteresis to prevent unstable condi-
tions.
Figure 1 : Reset Output Waveforms
L4964
3/13
Figure 2 : Soft Start Waveforms
Figure 3 : Current Limiter Waveforms
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
V
i
Input Voltage (pin 3)
36
V
V
i
V
2
Input to Output Voltage Difference
38
V
V
2
Output DC Voltage
Output Peak Voltage at t = 0.1
sec f = 100 kHz
1
7
V
V
V
12
Voltage at Pin 12
10
V
V
5
, V
7
, V
9
Voltage at Pins 5, 7 and 9
5.5
V
V
10
, V
6
, V
13
Voltage at Pins 10, 6 and 13
7
V
V
14
Voltage at Pin 14 (I
14
1 mA)
V
i
I
9
Pin 9 Sink Current
1
mA
I
11
Pin 11 Source Current
20
mA
I
14
Pin 14 Sink Current (V
14
< 5 V)
50
mA
P
tot
Power Dissipation at T
case
90
C
20
W
T
j
, T
stg
Junction and Storage Temperature
40 to 150
C
THERMAL DATA
Symbol
Parameter
Value
Unit
R
th j-case
Thermal Resistance Junction-case
Max.
3
C/W
R
th j-amb
Thermal Resistance Junction-ambient
Max.
35
C/W
L4964
4/13
ELECTRICAL CHARACTERISTICS
(refer to the test circuits T
j
= 25
o
C, V
i
= 25V, unless otherwise specified)
Symbol
Parameter
Test Conditions
Min.
Typ. Max.
Unit
Fig.
DYNAMIC CHARACTERISTICS (pin 6 to GND unless otherwise specified)
V
o
Output Voltage Range
V
i
= 36V, I
o
= 1A
V
ref
28
V
4
V
i
Input Voltage Range
V
o
= V
ref
to 28V, I
o
= 3A
9
36
V
4
V
o
Line Regulation
V
i
= 10V to 30V, V
o
= V
ref
, I
o
= 2A
15
70
mV
4
V
o
Load Regulation
I
o
= 1A to 2A
I
o
= 0.5A to 3A, V
o
= V
ref
10
15
30
50
mV
mV
4
4
V
ref
Internal Reference Voltage (Pin 10) V
i
= 9V to 36V, I
o
= 2A
4.95
5.1
5.25
V
4
V
ref
T
Average Temperature Coefficient
of Reference Voltage
T
j
= 0
C to 125
C, I
o
= 2A
0.4
mV/
C
V
d
Dropout Voltage between Pin 2
and Pin 3
I
o
= 3A
I
o
= 2A
2
1.5
3.2
2.4
V
V
4
4
Io
m
Maximum Operating Load Current
V
I
= 9V to 36V, V
o
= V
ref
to 28V
4
A
4
I
2L
Current Limiting Threshold (Pin 2)
V
i
= 9V to 36V, V
o
= V
re
f to 28V
4.5
8
A
4
I
SH
Input Average Current
V
i
= 36V, Output Short-circuited
80
140
mA
4
Efficiency
I
o
= 3A
V
o
= V
ref
V
o
= 12V
75
85
%
%
4
4
SVR
Supply Voltage Ripple Rejection
V
I
= 2V
rms
, f
ripple
= 100Hz
V
o
= V
ref
, I
o
= 2A
46
56
dB
4
f
Switching Frequency
40
50
60
kHz
4
f
V
i
Voltage Stability of Switching
Frequency
V
i
= 9V to 36V
0.5
%
4
f
T
j
Temperature Stability of Switching
Frequency
T
j
= 0
C to 125
C
1
%
4
f
max
Maximum Operating Switching
Frequency
V
o
= V
ref
, I
o
= 1A
120
kHz
T
sd
Thermal Shutdown Junction
Temperature
135
145
C
DC CHARACTERISTICS
I
3Q
Quiescent Drain Current
V
i
= 36V, V
7
= 0V, S1 : B, S2 : B
V
6
= 0V
V
6
= 3V
66
30
100
50
mA
6a
I
2L
Output Leakage Current
V
i
= 36V, V
6
= 3 V, V
7
= 0V
S1 : B, S2 : A
2
mA
6a
SOFT START
I
5so
Source Current
V
6
= 0V, V
5
= 3V
80
130
180
A
6b
I
5si
Sink Current
V
6
= 3V, V
5
= 3V
40
70
140
A
6b
INHIBIT
V
6L
Low Input Voltage
V
i
= 9V to 36V, V
7
= 0V
S1 : B, S2 : B
- 0.3
0.8
V
6a
V
6H
High Input Voltage
2
5.5
V
6a
I
6L
I
6H
Input Current with Input Voltage
Low Level
High Level
V
i
= 9V to 36V, V
7
= 0V
S1 : B, S2 : B
V
6
= 0.8V
V
6
= 2V
20
10
A
6a
ERROR AMPLIFIER
V
9H
High Level Output Voltage
V
10
= 4.7V, I
9
= 100
A, S1 : A,
S2 : A
3.4
V
6c
V
9L
Low Level Output Voltage
V
10
= 5.3V, I
9
= 100
A, S1 : A,
S2 : E
0.6
V
6c
I
9 si
Sink Output Current
V
10
= 5.3V, S1 : A, S2 : B
100
150
A
6c
I
9 so
Source Output Current
V
10
= 4.7V, S1 : A, S2 : D
100
150
A
6c
L4964
5/13
ELECTRICAL CHARACTERISTICS (continued)
(refer to the test circuits T
j
= 25
o
C, V
i
= 25V, unless otherwise specified)
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
Fig.
ERROR AMPLIFIER (continued)
I
10
Input Bias Current
V
10
= 5.2V, S1 : B
2
20
A
6c
G
v
DC Open Loop Gain
V
9
= 1V to 3V, S1 : A, S2 : C
40
55
dB
6c
OSCILLATOR AND PWM COMPARATOR
I
7
Input Bias Current of
PWM Comparator
V
7
= 0.5V to 3.5V
10
A
6a
I
11
Oscillator Source Current
V
11
= 2V, S1 : A, S2 : B
4
mA
6a
RESET
V
12R
Rising Threshold Voltage
V
i
= 9 V to 36 V, S1 : B, S2 : B
V
ref
- 150mV
V
ref
- 100mV
V
ref
- 50mV
V
6d
V
12F
Falling Threshold Voltage
4.75
V
ref
- 150mV
V
ref
- 100mV
V
6d
V
13D
Delay Threshold Voltage
V
12
= 5.3 V, S1 : A, S2 : B
4.3
4.5
4.7
V
6d
V
13H
Delay Threshold Voltage
Hysteresis
100
mV
6d
V
14S
Output Saturation Volt.
I
14
= 5mA, V
12
= 4.7V - S1, S2 : B
0.4
V
6d
I
12
Input Bias Current
V
12
= 0V to V
ref
, S1 : B, S2 : B
1
10
A
6d
I
13 so
I
13 si
Delay Source Current
Delay Sink Current
V
13
= 3V, S1 : A, S2 : B
V
12
= 5.3V
V
12
= 4.7V
60
8
110
150
A
mA
6d
I
14
Output Leakage Current
V
i
= 36V, V
12
= 5.3V, S1 : B, S2 : A
100
A
6d
C7, C8 : EKR (ROE)
L1 : L = 300
H at 8 A
R = 500 m
Core type : MAGNETICS 58930 - A2 MPP
N
turns : 43
Wire Gauge : 1 mm (18 AWG)
Figure 4 : Dynamic Test Circuit
L4964
6/13
Figure 5 : PC. Board and Component Layout of the Circuit of Fig. 4 (1:1 scale)
L4964
7/13
Figure 6 : DC Test Circuits.
Figure 6a.
Figure 6b.
Figure 6c.
1 - Set V
10
FOR V
9
= 1 V
2 - Change V
10
to obtain V
9
= 3 V
3 - G
V
=
DV
9
=
2 V
V
10
V
10
Figure 6d.
L4964
8/13
Figure 7 : Switching Frequency vs. R1 (see fig. 4).
Figure 8 : Open Loop Frequency and Phase Res-
ponse of Error Amplifier (see fig. 6c).
Figure 9 : Reference Voltage (pin 10) vs. Junc-
tion Temperature (see fig. 4).
Figure 10 : Power Dissipation (L4964 only) vs.
Input Voltage.
Figure 11 : Efficiency vs. Output Voltage.
Figure 12 : Power Dissipation Derrating Curve.
L4964
9/13
APPLICATION INFORMATION
CHOOSING THE INDUCTOR AND CAPACITOR
The input and output capacitors of the L4964 must
have a low ESR and low inductance at high current
ripple.
Preferably, the inductor should be a toroidal type or
wound on a Moly-Permalloy nucleus.Saturation
must not occur at current levels below 1.5 times the
current limiter level. MPP nuclei have very soft satu-
ration characteristics.
L =
(
V
i
-
V
o
)
V
0
V
i
f
I
L
, C =
(
V
i
-
V
o
)
V
0
8L f
2
V
o
I
L
= Inductance current ripple
V
o
= Output ripple voltage
Figure 13 : Typical Application Circuit.
SUGGESTED INDUCTOR (L1)
Core Type
No
Turns
Wire
Gauge
(mmm)
Air
Gap
(mm)
Magnetics 58930 A2MPP
43
1.0
Thomson GUP 20 x 16 x 7
50
0.8
0.7
Siemens EC 35/17/10
(B6633& G0500 X127)
40
2 x 0.8
VOGT 250
H Toroidal Coil, Part Number
5730501800
Resistor Values for Standard Output Volt-
ages
V
0
R8
R7
12 V
15 V
18 V
4.7 k
4.7 k
4.7 k
6.2 k
9.1 k
12 k
L 4964
C7, C8 : EKR (ROE)
Figure 14 : P.C. Board and Component Layout of the Circuit of Fig. 13 (1:1 scale)
L4964
10/13
PMMUL15V.EPS
MULTIWATT15 (Vertical) PACKAGE MECHANICAL DATA
Dimensions
Millimeters
Inches
Min.
Typ.
Max.
Min.
Typ.
Max.
A
5
0.197
B
2.65
0.104
C
1.6
0.063
D
1
0.039
E
0.49
0.55
0.019
0.022
F
0.66
0.75
0.026
0.030
G
1.14
1.27
1.4
0.045
0.050
0.055
G1
17.57
17.78
17.91
0.692
0.700
0.705
H1
19.6
0.772
H2
20.2
0.795
L
22.1
22.6
0.870
0.890
L1
22
22.5
0.866
0.886
L2
17.65
18.1
0.695
0.713
L3
17.25
17.5
17.75
0.679
0.689
0.699
L4
10.3
10.7
10.9
0.406
0.421
0.429
L7
2.65
2.9
0.104
0.114
M
4.2
4.3
4.6
0.165
0.169
0.181
M1
4.5
5.08
5.3
0.177
0.200
0.209
S
1.9
2.6
0.075
0.102
S1
1.9
2.6
0.075
0.102
Dia. 1
3.65
3.85
0.144
0.152
MUL15V.TBL
L4964
11/13
F
G
G1
L2
L1
L7
S
H1
L3
S1
L4
H2
Dia. 1
A
L5
C
L6
E
L
B
PMMUL15H.EPS
MULTIWATT15 (Horizontal) PACKAGE MECHANICAL DATA
Dimensions
Millimeters
Inches
Min.
Typ.
Max.
Min.
Typ.
Max.
A
5
0.197
B
2.65
0.104
C
1.6
0.063
E
0.49
0.55
0.019
0.022
F
0.66
0.75
0.026
0.030
G
1.14
1.27
1.4
0.045
0.050
0.055
G1
17.57
17.78
17.91
0.692
0.700
0.705
H1
19.6
0.772
H2
20.2
0.795
L
20.57
0.810
L1
18.03
0.710
L2
2.54
0.100
L3
17.25
17.5
17.75
0.679
0.689
0.699
L4
10.3
10.7
10.9
0.406
0.421
0.429
L5
5.28
0.208
L6
2.38
0.094
L7
2.65
2.9
0.104
0.114
S
1.9
2.6
0.075
0.102
S1
1.9
2.6
0.075
0.102
Dia. 1
3.65
3.85
0.144
0.152
MUL15H.TBL
L4964
12/13
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for
the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its
use. No license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifica-
tions mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information pre-
viously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or
systems without express written approval of SGS-THOMSON Microelectronics.
1994 SGS-THOMSON Microelectronics - All Rights Reserved
MULTIWATT
is a Registered Trademark of SGS-THOMSON Microelectrinics
SGS-THOMSON Microelectronics GROUP OF COMPANIES
Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore -
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L4964
13/13