SG2549 Microsemi Corporation, SG2549 Datasheet - Page 3

• Manufacturer Part Number: SG2549
• Description: Current Sense Latch
• Manufacturer: Microsemi Corporation

4/90 Rev 1.1 2/94
Copyright
ELECTRICAL CHARACTERISTICS
(V
TYPICAL SWITCHING CHARACTERISTICS
(V
Note 4: These parameters, although guaranteed, are not tested in production.
DYNAMIC TEST CIRCUIT
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 R
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, C
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 C
will enhance recovery.
APPLICATION NOTES
HI Output Section
Off Voltage
On Voltage
LO Output
Off Leakage
On Voltage
Reset Minimum Pulse Width (T
Delay from Reset to LO Output (T
LO Input Minimum Pulse Width (T
Delay from LO Input to LO Output (T
Delay from HI Input to LO Output (T
Delay from HI Output to LO Output
S
S
= 5V, and over recomended operating temperature, unless otherwise specified.)
= 5V, T
1994
A
= 25 C)
SC
Parameter
is determined by dividing the 100mV input threshold by
C
Parameter
, which may cause slow recovery from pulse limiting.
W1
)
D(OFF)
W2
C
D(ON)
)
, and perhaps a diode across R
D(ON)
I
V
I
L
L
)
PIN 5
= 1mA
= 5mA
)
)
= 40V
Amplitude = 3.0V
R
LO CM Amplitude = 200mV
LO CM Amplitude = 200mV, R
Amplitude = 200mV, V
LO CM Input = 200mV
L
(Note 4)
= 470 to V
Test Conditions
3
S
SWITCHING WAVEFORMS
Test Conditions
C
,
CM
= 5V
FIGURE 1 — HIGH LINE SENSING WITH THE SG1549 IN CONJUNCTION
L
= 470
SG1549/SG2549/SG3549
Min. Typ. Max. Min. Typ. Max.
2.8
SG1549/2549
WITH AN SG1524 PWM CONTROL IC
to V
3.2
.01
S
.3
0
11861 Western Avenue
0.1
1.0
0.5
L
Min. Typ. Max.
INFINITY Microelectronics Inc.
[phone]
SG1549 Series
2.8
SG3549
150
300
180
300
3.2
.01
50
30
.3
0
Garden Grove, CA 92841
300
600
300
360
900
0.1
1.0
0.5
60
FAX: [phone]
Units
Units
ns
ns
ns
ns
ns
ns
V
V
V
A