SG3844DM Microsemi Analog Mixed Signal Group, SG3844DM Datasheet - Page 12
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SG3844DM
Manufacturer Part Number
SG3844DM
Description
IC PWM CURRENT MODE 8SOIC
Manufacturer
Microsemi Analog Mixed Signal Group
Datasheet
1.SG3845M.pdf
(12 pages)
Specifications of SG3844DM
Pwm Type
Current Mode
Number Of Outputs
1
Frequency - Max
500kHz
Duty Cycle
50%
Voltage - Supply
8.2 V ~ 30 V
Buck
Yes
Boost
No
Flyback
No
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
Yes
Operating Temperature
0°C ~ 70°C
Package / Case
8-SOIC
Frequency-max
500kHz
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
SG3844DM
Manufacturer:
Microsemi Analog Mixed Signal
Quantity:
1 791
12
SG1844/SG1845 Series
Softstart and adjustable peak current can be done with the external
circuitry shown above.
The oscillator is programmed by the values selected for the timing
components R
calculation of the component values.
FIGURE 18. — ADJUSTABLE BUFFERED REDUCTION OF CLAMP LEVEL
I
PK
C
=
and V
V
R
1
S
1
R
R
Where: 0 ≤ V
=
2
1
FIGURE 20. — OSCILLATOR CONNECTION
T
SG1844/45
2N2907
and C
1.43 - 0.23
Discharge
8 (14)
Current
4 (7)
2 (3)
1 (1)
1+
T
. Refer to application information for
2.8V
1.1V
R
R
1
2
1
WITH SOFTSTART
≤ 1.0V
SG1844/45
R
R
1
2
I
d
= 8.2mA
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
T Y P I C A L A P P L I C A T I O N C I R C U I T S
5 (9)
t
SOFTSTART
5V
7 (12)
where: V
C
7 (11)
6 (10)
U R R E N T
P
= -ln 1 -
R O D U C T I O N
7 (11)
6 (10)
5 (8)
3 (5)
V
2
CC
=
R
C
T
T
V
V
1+
- M
C
2
0.5
V
R
R
IN
C
1
2
Q1
R
O D E
S
R
R
1
1
+R
R
2
2
P W M C
D
Precision duty cycle limiting for a duty cycle of <50%, as well as
synchronizing several 1844/45's is possible with the above circuitry.
Error amplifier is capable of sourcing and sinking current up to 0.5mA.
A T A
O N T R O L L E R
C
f =
f =
FIGURE 19. — EXTERNAL DUTY CYCLE CLAMP AND
R
S
FIGURE 21. — ERROR AMPLIFIER CONNECTION
i
R
(R
H E E T
R
R
A
A
B
R
A
+ 2R
R
F
1.44
+ 2R
B
³ 10K
6
2
R
MULTI-UNIT SYNCHRONIZATION
F
B
B
(continued)
)C
2 (3)
1 (1)
8
TIMER
555
2.5V
4
1
SG1844/45
3
SG1844/45
To other
8 (14)
4 (7)
SG1844/45
0.5mA
Copyright © 2000
Rev. 1.6c
5 (9)