ML4863CS Micro Linear, ML4863CS Datasheet - Page 8

• Manufacturer Part Number: ML4863CS
• Description: High Efficiency Flyback Controller
• Manufacturer: Micro Linear

ML4863
DESIGN CONSIDERATIONS
3c.
3d.
4a.
4b.
Based on these calculations, the design should use two
100µF capacitors, with an ESR of 100m each, in parallel
to meet the capacitance and ESR requirements.
5.
Since the inequality is met, the circuit should be stable.
Some typical application circuits are shown in Figures 2, 3,
and 4.
8
V IN
47µF
R
C
ESR
0 50
Specify the inductor’s DC winding resistance:
L
Specify the coupled inductor's turn ratio:
Np : Ns = 1:1
Calculate the minimum output capacitance
required using equation 5.
Establish the maximum ESR for the output
capacitor using equation 6.
As a final design check, evaluate the system
stability using equation 7.
100
.
DCR
0 1 0 12
150
mV
.
= 90m

 
mV
5 6
V IN
SENSE
SHDN
V FB
.
Figure 2. 5V, 1A Circuit
5
(
6 10
ML4863
= 80m
OUT 2
OUT 1
GND
V CC
25 10
.
6
)
0 1
.
!
0 12
1µF
.
18 10
6
= 55µF
Coiltronics
(
CTX20-4
5 4
–6
(Continued)
)
"
$ #
= 360mV (7a)
NDS9955
100m
400µF
(5a)
(6a)
V OUT
5V, 1A
LAYOUT
Good PC board layout practices will ensure the proper
operation of the ML4863. Important layout considerations
follow:
• The connection from the current sense resistor to the
• The V
• Trace lengths from the capacitors to the inductor, and
• Power and ground planes must be large enough to
See Figure 5 for a sample PC board layout.
V IN
100µF
SENSE pin of the ML4863 should be made by a
separate trace and connected right at the sense resistor
lead.
the ML4863 for adequate filtering of the IC's internal
bias voltage.
from the inductor to the FET should be as short as
possible to minimize noise and ground bounce.
handle the current the converter has been designed for.
CC
bypass capacitor needs to be located close to
V IN
SENSE
SHDN
V FB
Figure 3. 5V, 2A Circuit
ML4863
OUT 2
OUT 1
GND
V CC
1µF
NDS9410
LPE6562
Dale
NDS9410
50m
800µF
V OUT
5V, 2A