MAX5019ESA+T Maxim Integrated Products, MAX5019ESA+T Datasheet - Page 12

• Manufacturer Part Number: MAX5019ESA+T
• Description: IC CNTRLR PWM CRNT MD 8-SOIC
• Manufacturer: Maxim Integrated Products

Specifications of MAX5019ESA+T

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 302kHz
• Duty Cycle: 85%
• Voltage - Supply: 13 V ~ 110 V
• Buck: No
• Boost: No
• Flyback: Yes
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: Yes
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-SOIC (3.9mm Width)
• Frequency-max: 302kHz
• Duty Cycle (max): 85 %
• Output Current: 1000 mA
• Mounting Style: SMD/SMT
• Switching Frequency: 275 KHz
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Synchronous Pin: No
• Topology: Flyback, Forward
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Current-Mode PWM Controllers with Integrated
Startup Circuit
5) Choose the tertiary winding turns ratio (N
6) Choose R
12
Choose MOSFETs with appropriate avalanche
power ratings.
that the minimum input voltage provides the mini-
mum operating voltage at V
ing equation to calculate the tertiary winding turns
ratio:
where:
V
V
V
V
in this design example).
N
N
Choose N
where:
V
voltage (0.465V).
N
example).
I
this example).
OUTMAX
DDMIN
DDMAX
IN_MIN
IN_MAX
ILim
P
T
S
______________________________________________________________________________________
/N
is the number of turns of the tertiary winding.
is the number of turns of the primary winding.
P
is the current-sense comparator trip threshold
is the secondary side turns ratio (5/14 in this
V
is the minimum V
is the minimum input supply voltage (36V).
is the maximum V
is the maximum input supply voltage (72V
SENSE
DSMAX
is the maximum DC output current (10A in
T
R
R
= 6.
SENSE
SENSE
5 33
13 7
36
.
V
V
.
≥
DDMIN
DDMAX
according to the following equation:
V
V
7
≤
≤
≤
IN_MIN
IN_MAX
×
2
N
1
14
V
N
N
5
4
T
P
S
×
+
0 465
+
≤
≤
×



×
0 7
.
N
0 7
7 14
1 +
1 2 10
.
1 2 . I
.
DD
.
T
.
V
DD
≤
ILIM
×
DD
V
×
×
×
supply voltage (13V).
36 7
14
14
N
N
72
supply voltage (36V).
OUTMAX
P
(13V). Use the follow-
P
.

 =

≤
=
N
109
×
144
T
14
≤
m
V
Ω
T
/N
P
) so
All connections carrying pulsed currents must be very
short, be as wide as possible, and have a ground plane
as a return path. The inductance of these connections
must be kept to a minimum due to the high di/dt of the
currents in high-frequency switching power converters.
Current loops must be analyzed in any layout pro-
posed, and the internal area kept to a minimum to
reduce radiated EMI. Ground planes must be kept as
intact as possible.
TRANSISTOR COUNT: 589
PROCESS: BiCMOS
7) Choose the inductor value so that the peak ripple
8) The size and ESR of the output filter capacitor deter-
current (LIR) in the inductor is between 10% and
20% of the maximum output current.
where V
age drop (0.5V).
mine the output ripple. Choose a capacitor with a
low ESR to yield the required ripple voltage.
Use the following equations to calculate the peak-to-
peak output ripple:
where:
V
V
capacitive ripple. Calculate the ESR ripple and
capacitive ripple as follows:
V
V
RIPPLE
RIPPLE,ESR
RIPPLE,C
RIPPLE,ESR
L
V
D
L
is the combined RMS output ripple due to
RIPPLE
≥
≥
is the output Schottky diode forward volt-
= I
Layout Recommendations
0 4 275
2
( )
.
= I
, the ESR ripple, and V
RIPPLE
5 5
×
(
.
×
V
LIR
=
RIPPLE
OUT
×
V
×
(
/(2 x π x 275kHz x C
1 0 198
RIPPLE ESR
kHz
2
+
275
-
V
x ESR
D
.
kHz I
×
)
,
×
Chip Information
10
(
)
1
A
×
-
+
D
OUTMAX
=
V
MIN
RIPPLE C
4 01
2
.
)
µ
H
,
RIPPLE,C
OUT
)
, the