SG1549 [MICROSEMI]
CURRENT SENSE LATCH; 电流检测LATCH
| 型号： | SG1549 |
| 厂家： | 
Microsemi |
| 描述： | CURRENT SENSE LATCH |
| 文件： | 总4页 (文件大小：78K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SG1549/SG2549/SG3549
CURRENT SENSE LATCH
DESCRIPTION
FEATURES
• Current sensing with 100mV
threshold
• Common-mode input at ground or
to 40V
• Complementary outputs
• Automatic reset from PWM clock
• 180ns delay
This monolithic integrated circuit is an analog latch device with digital reset. It was
specifically designed to provide pulse-by-pulse current limiting for switch-mode power
supply systems, but many other application are also feasible. Its function is to provide
a latching switch action upon sensing an input threshold voltage, with reset accom-
plished by an external clock signal. This device can be interfaced directly with many
kinds of pulse width modulating control IC's, including the SG1524, SG1525A and
SG1527A.
• Interface direct to SG1524,
SG1525A, SG1527A
The input threshold for the latch circuit is 100mV, which can be referenced either to
ground or to a wide-ranging positive voltage. There are high and low-going output
signals available, and both the supply voltage and clock signal can be taken directly
from an associated PWM control chip.
HIGH RELIABILITY FEATURES
- SG1549
With delays in the range of 200 nanoseconds, this latch circuit is ideal for fast reaction
sensing to provide overall current limiting, short circuit protection, or transformer
saturation control.
♦ Available to MIL-STD-883
♦ LMI level "S" processing available
♦ Radiation data available
BLOCK DIAGRAM
SCHEMATIC
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
1
(714) 898-8121 ∞ FAX: (714) 893-2570
SG1549/SG2549/SG3549
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage, VS ..................................................... 25V
HI CM Input Voltage ............................................................ 40V
LO Output "off" Voltage ....................................................... 40V
LO Output "on" current ..................................................... 25mA
Operating Junction Temperature
Hermetic (Y Package) .................................................. 150°C
150°C
Plastic (N Package) ......................................................
Storage Temperature Range ............................ -65°C to 150°C
Note 1. Values beyond which damage may occur.
THERMAL DATA
Y Package:
Note A. Junction Temperature Calculation: TJ = TA + (PD x θJA).
Note B. The above numbers for θJC are maximums for the limiting
thermal resistance of the package in a standard mount-
ing configuration. The θJA numbers are meant to be
guidelines for the thermal performance of the device/pc-
board system. All of the above assume no ambient
airflow.
Thermal Resistance-Junction to Case, θJC .................. 50°C/W
Thermal Resistance-Junction to Ambient, θJA ............ 130°C/W
M Package:
Thermal Resistance-Junction to Case, θJC .................. 60°C/W
Thermal Resistance-Junction to Ambient, θJA ............. 95°C/W
RECOMMENDED OPERATING CONDITIONS (Note 2)
Input Supply Voltage, VS .................................................... 5.0V
HI CM Input Voltage .................................................. 2V to 40V
LO Output "off" Voltage ............................................. 5V to 40V
LO Output "on" Current ............................................. 0 to 10mA
Reset LO Voltage ..................................................... 0V to 0.8V
Reset HI Voltage .................................................... 2.5V to 5.0V
Operating Ambient Temperature Range
SG1549Y ....................................................... -55°C to 125°C
SG2549Y or M ................................................. -25°C to 85°C
SG3549Y or M ....................................................
0°C to 70°C
Note 2. Range over which the device is functional.
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for SG1549 with -55°C ≤ TA ≤ 125°C, SG2549 with
-25°C ≤ TA ≤ 85°C, SG3549 with 0°C ≤ TA ≤ 70°C, and VS = 5V. Low duty cycle pulse testing techniques are used which maintains junction and case
temperatures equal to the ambient temperature.)
SG1549/2549
SG3549
Parameter
Supply Section
Test Conditions
Units
Min. Typ. Max. Min. Typ. Max.
Supply Current
VPIN 8 = 5V
PIN 8 = 20V
2
10
3
15
2
10
5
15
mA
mA
V
LO CM Input Section (Note 3)
120 80 100
70 100 130 70 100
400 500 600 400 500 600
300 500 700 300 500
Threshold Voltage
Pin 1 & 2 shorted, TA = 25°C
pin 1 & 2 shorted
VPIN 3 = 50mV, TA = 25°C
VPIN 3 = 50mV
80 100
120
130
mV
mV
Ω
Input Impedance
700
Ω
HI CM Input Section (Note 3)
Threshold Voltage
VCM = 2V, Pin 3 open, TA = 25°C
80 100 120 80 100 120
80 100 120 80 100 120
70 100 130 70 100 130
70 100 130 70 100 130
mV
mV
mV
mV
µA
V
CM = 40V, Pin 3 open, TA = 25°C
VCM = 2V, Pin 3 open
CM = 40V, Pin 3 open
VPIN 1 = VPIN 2 = 40V
V
Input Current
200 300
200 300
Clock Reset Section
Min. Trigger Voltage
Input Current
2.0 2.5
2.0 2.5
V
µA
VPIN 7 = 4V
20
40
20
40
Note 3. Input threshold voltages and supply current are directly proportional to supply voltage, VS .
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
(714) 898-8121 FAX: (714) 893-2570
2
∞
SG1549/SG2549/SG3549
ELECTRICAL CHARACTERISTICS
(VS = 5V, and over recomended operating temperature, unless otherwise specified.)
SG1549/2549
SG3549
Min. Typ. Max.
Parameter
HI Output Section
Test Conditions
Units
Min. Typ. Max.
Off Voltage
On Voltage
0
0.1
0
3.2
0.1
V
V
IL = 1mA
2.8 3.2
2.8
LO Output
Off Leakage
On Voltage
VPIN 5 = 40V
IL = 5mA
.01 1.0
0.5
.01 1.0
.3
µA
V
.3
0.5
TYPICAL SWITCHING CHARACTERISTICS (Note 4)
(VS = 5V, TA = 25°C)
SG1549 Series
Min. Typ. Max.
150 300
Parameter
Test Conditions
Units
Reset Minimum Pulse Width (TW1
Delay from Reset to LO Output (TD(OFF)
LO Input Minimum Pulse Width (TW2
Delay from LO Input to LO Output (TD(ON)
Delay from HI Input to LO Output (TD(ON)
Delay from HI Output to LO Output
)
Amplitude = 3.0V
RL = 470Ω to VS
ns
ns
ns
ns
ns
ns
600
)
300
)
LO CM Amplitude = 200mV
50 300
180 360
300 900
)
LO CM Amplitude = 200mV, RL = 470Ω to VS
Amplitude = 200mV, VCM = 5V
LO CM Input = 200mV
)
30
60
Note 4: These parameters, although guaranteed, are not tested in production.
DYNAMIC TEST CIRCUIT
SWITCHING WAVEFORMS
APPLICATION NOTES
HIGH LINE SENSING - The SG1549 will provide current sensing in the
positive supply line in the typical SG1524 single-ended switching
regulator application shown in Figure 1. The HI CM sense circuitry can
be used with input voltages between 2 and 40 volts.
A value for RSC is determined by dividing the 100mV input threshold by
the peak current desired. High-frequency noise, or switching transients,
can usually be eliminated by a small capacitor between pins 3 and 4.
Current control may be accomplished by either the HI OUTPUT pin
connected to the SG1524’s Shutdown pin, or the LO OUTPUT pin
connected directly to the Compensation Terminal. In either case,
activation of the current sense latch will tend to discharge the compen-
sation capacitor, CC, which may cause slow recovery from pulse limiting.
If this feature is desired, the LO OUTPUT pin may be used to discharge
a soft-start network instead of coupling directly to the SG1524. If it is not
desired, the use of a small value of CC, and perhaps a diode across RC,
will enhance recovery.
FIGURE 1 — HIGH LINE SENSING WITH THE SG1549 IN CONJUNCTION
WITH AN SG1524 PWM CONTROL IC
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
3
(714) 898-8121 ∞ FAX: (714) 893-2570
SG1549/SG2549/SG3549
APPLICATION NOTES (continued)
Another method of introducing the current shutdown signal is shown in
Figure 2 where the SG1524 is used to activate a constant drive current
to the high-current switch, in this case an SM600. The 2N2222 forms a
constant current generator when driven from the SG1524’s 5.0 volt
reference through a 1K resistor. This transistor is then switched off by
the LO OUTPUT transistor in the SG1549, achieving the fastest re-
sponse to the output of the regulator.
LOW LINE SENSING - In many types of feed-forward or push-pull
converters, current protection may be provided by sensing in an emitter
resistor referenced to ground on the primary side of an output trans-
former. The fast-reacting SG1549 can easily sense secondary overload
as reflected back to the primary and, additionally, provide protection
from unbalanced transformer saturation.
FIGURE 2 — CURRENT CONTROL FOR A BUCK REGULATOR WITH
CONSTANT DRIVE CURRENT
When using the LO CM inputs, the HI CM inputs should be shorted
together. While the LO CM inputs may be connected directly across a
sense resistor, RSC, a small low-pass filter as shown in Figure 3 is often
required to eliminate high frequency transients. It must be remembered
that the 500Ωinput impedance at the LO CM terminals will cause the use
of R1 to increase the effective threshold; however, this also offers the
possibility of an easily adjustable threshold by incorporating a potenti-
ometer at the input.
Coupling the output signal from the SG1549 to the control chip may be
done in several ways including the use of either the Compensation or
Shutdown pins on the SG1524 as described earlier.
Another convenient way to tie the output of the SG1549 into the PWM
control in higher power applications is by using the SG1627 Dual
Interface Driver and connecting the LO OUTPUT terminal of the Sg1549
directlytothetwoNon-InvertinginputsoftheSG1627asshowninFigure
4.
FIGURE 3 — A PUSH-PULL CONVERTER WITH LOW-LINE
EMITTER CURRENT SENSING
And finally, keep in mind that the LO OUTPUT terminal of the SG1549
will easily drive most high-speed optical couplers should some type of
isolation between current sense and shutdown control be required.
FIGURE 4 — POWER BOOST AND CURRENT CONTROL WITH THE SG1627
CONNECTION DIAGRAMS & ORDERING INFORMATION (See Notes Below)
Ambient
Temperature Range
Package
Part No.
Connection Diagram
8-PIN CERAMIC DIP
Y - PACKAGE
SG1549Y/883B
SG1549Y/DESC
SG1549Y
SG2549Y
SG3549Y
-55°C to 125°C
-55°C to 125°C
-55°C to 125°C
-25°C to 85°C
0°C to 70°C
8
7
6
5
+ HI CM INPUT
— HI CM INPUT
+ LO CM INPUT
1
2
3
4
+VS
CLOCK RESET
HI OUTPUT
LO OUTPUT
— LO CM INPUT
8-PIN PLASTIC DIP
M - PACKAGE
SG2549M
SG3549M
-25°C to 85°C
0°C to 70°C
Note1. Contact factory for JAN and DESC product availability.
2. All parts are viewed from the top.
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
(714) 898-8121 FAX: (714) 893-2570
4
∞
相关型号：
SG1549Y-883B
Power Supply Support Circuit, Adjustable, 1 Channel, +.1/+40.1VV, BIPolar, CDIP8, CERAMIC, DIP-8
MICROSEMI
SG1549Y-DESC
Power Supply Support Circuit, Adjustable, 1 Channel, BIPolar, CDIP8, CERAMIC, DIP-8
MICROSEMI
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