UC384XBD MOTOROLA [Motorola, Inc], UC384XBD Datasheet - Page 10

• Manufacturer Part Number: UC384XBD
• Description: HIGH PERFORMANCE CURRENT MODE CONTROLLERS
• Manufacturer: MOTOROLA [Motorola, Inc]

C
V Clamp
R 2
R 1
t Soft-Start
10
R 2
R 1
8(14)
V Clamp
4(7)
2(3)
1(1)
8(14)
4(7)
2(3)
1(1)
Figure 19. Adjustable Reduction of Clamp Level
MPSA63
Figure 21. Adjustable Buffered Reduction of
+ *
R 2
R 1
EA
1.67
R
R
)
EA
R 2
R 1
R
R
+
In 1
1.67
1
Osc
Bias
+
)
1.0 mA
Clamp Level with Soft–Start
Osc
+ 0.33x10 –3
Bias
1.0 mA
*
1
2R
3V Clamp
R
2R
R
Where: 0 V Clamp 1.0 V
V C
V Clamp
5(9)
1.0V
–
V Clamp
+
1.0V
5(9)
5.0V Ref
–
+
R 1
C R 1 R 2
R 1 R 2
5.0V Ref
)
R 1
Comp/Latch
R 2
)
Comp/Latch
S
R
T
R 2
Q
S
R
T
Where: 0 V Clamp 1.0 V
I pk(max)
Q
UC3844B, 45B UC2844B, 45B
I pk(max)
+
–
+
–
7(12)
[
V CC
7(12)
V CC
V Clamp
7(11)
6(10)
5(8)
3(5)
[
R S
7(11)
6(10)
5(8)
3(5)
V Clamp
R S
V in
Q1
R S
V in
Q1
R S
–
+
Virtually lossless current sensing can be achieved with the implementation
of a SENSEFET power switch. For proper operation during over–current
conditions, a reduction of the I pk(max) clamp level must be implemented.
Refer to Figures 19 and 21.
5.0V Ref
C
Figure 22. Current Sensing Power MOSFET
Control Circuitry Ground:
1.0M
S
R
8(14)
4(7)
2(3)
1(1)
Comp/Latch
t Soft–Start 3600C in F
T
Q
To Pin (9)
Figure 20. Soft–Start Circuit
MOTOROLA ANALOG IC DEVICE DATA
+
–
EA
(12)
R
R
V CC
+
(11)
(10)
(8)
(5)
Osc
1.0mA
Bias
G
1/4 W
R S
2R
D SENSEFET
M
R
V in
5(9)
Then : V Pin 5
V Pin 5
If: SENSEFET = MTP10N10M
K
To Input Source
S
Power Ground:
1.0V
–
+
Return
5.0V Ref
[
R S = 200
R S I pk r DS(on)
r DM(on)
[
R
S
T
0.075 I pk
Q
)
R S