NCV3843BV ON Semiconductor, NCV3843BV Datasheet - Page 13

• Manufacturer Part Number: NCV3843BV
• Description: High Performance Current Mode Controllers
• Manufacturer: ON Semiconductor

C
−
+
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
1.0M
Figure 26. Current Sensing Power MOSFET
5.0V Ref
8(14)
4(7)
2(3)
1(1)
Comp/Latch
pk(max)
S
R
t
Soft−Start
Q
Control Circuitry Ground:
Figure 24. Soft−Start Circuit
clamp level must be implemented. Refer to Figures 23 and 25.
≈ 3600C in mF
To Pin (9)
EA
+
R
R
−
+
(12)
UC3842B, UC3843B, UC2842B, UC2843B, NCV3843BV
Osc
1.0mA
Bias
V
(11)
(10)
(8)
(5)
CC
2R
G
R
1/4 W
S
R
−
+
D
M
5(9)
1.0V
SENSEFET
V
in
Then : V Pin 5 [ 0.075 I pk
V Pin 5 [
If: SENSEFET = MTP10N10M
R
5.0V Ref
K
S
To Input Source
S
Power Ground:
= 200
Return
R
S
r DM(on) ) R S
R S I pk r DS(on)
Q
http://onsemi.com
C
13
R
R
2
1
8(14)
t Soft-Start + * In 1 *
4(7)
2(3)
1(1)
MPSA63
Figure 25. Adjustable Buffered Reduction of
V Clamp [
Figure 27. Current Waveform Spike Suppression
EA
R
R
+
−
+
R 2
R 1
Clamp Level with Soft−Start
The addition of the RC filter will eliminate instability caused by the leading
edge spike on the current waveform.
Osc
1.67
Bias
1.0 mA
) 1
5.0V Ref
Comp/Latch
3 V Clamp
2R
V C
R
R
S
Where: 0 ≤ V
V
Q
Clamp
C
1.0V
5(9)
R 1 ) R 2
−
+
R 1 R 2
5.0V Ref
Clamp
Comp/Latch
7(12)
+
≤ 1.0 V
−
R
S
V
CC
I pk(max) [
Q
7(11)
6(10)
5(8)
3(5)
+
−
C
R
V Clamp
7(12)
R S
V
CC
Q1
R
V
7(11)
6(10)
5(8)
3(5)
in
S
Q1
V
R
in
S