MP1493 – 3A, 4.2V-16V INPUT, FAST TRANSIENT SYNCHRONOUS STEP-DOWN CONVERTER
MP1493 Rev. 1.11 www.MonolithicPower.com 13
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Figure 4—Simplified Circuit in PWM Mode
without External Ramp Compensation
Table 1—300kHz recommended parameters
without External Ramp Compensation
Recommended Conditions: V
IN
=12V, I
OUT
=3A
V
OUT
(V)
L
(μH)
R1
(kΩ)
R2
(kΩ)
Rfreq
(kΩ)
1.2 3.3 12.1 26.1 402
2.5 3.3 30 14.3 820
3.3 3.3 40.2 13.3 1000
Table 2—500kHz recommended parameters
without External Ramp Compensation
Recommended Conditions: V
IN
=12V, I
OUT
=3A
V
OUT
(V)
L
(μH)
R1
(kΩ)
R2
(kΩ)
Rfreq
(kΩ)
1.2 3.3 12.1 26.1 240
2.5 3.3 30 14.3 510
3.3 3.3 40.2 13.3 649
Table 3—700kHz recommended parameters
without External Ramp Compensation
Recommended Conditions: V
IN
=12V, I
OUT
=3A
V
OUT
(V)
L
(μH)
R1
(kΩ)
R2
(kΩ)
Rfreq
(kΩ)
1.2 2.2 12.1 26.1 174
2.5 2.2 30 14.3 348
3.3 2.2 40.2 13.3 475
As Figure 5 shown, when output cap is ceramic
CAP with lower ESR, external ramp is needed.
Recommended parameters are as below Table 4
to Table 6 shown.
Figure 5—Simplified Circuit in PWM Mode
with External Ramp Compensation
Table 4—300kHz recommended parameters
with External Ramp Compensation
Recommended Conditions: V
IN
=12V, I
OUT
=3A
V
OUT
(V)
L
(μH)
R1
(kΩ)
R2
(kΩ)
R4
(kΩ)
C4
(pF)
Rfreq
(kΩ)
1.2
3.3
12.1 26.1 330 220 402
2.5
3.3
30 14.3 698 220 820
3.3
3.3
40.2 12.7 698 220 1000
Table 5—500kHz recommended parameters
with External Ramp Compensation
Recommended Conditions: V
IN
=12V, I
OUT
=3A
V
OUT
(V)
L
(μH)
R1
(kΩ)
R2
(kΩ)
R4
(kΩ)
C4
(pF)
Rfreq
(kΩ)
1.2
3.3
12.1 26.1 402 220 240
2.5
3.3
30 14.3 549 220 510
3.3
3.3
40.2 12.7 698 220 649
Table 6—700kHz recommended parameters
with External Ramp Compensation
Recommended Conditions: V
IN
=12V, I
OUT
=3A
V
OUT
(V)
L
(μH)
R1
(kΩ)
R2
(kΩ)
R4
(kΩ)
C4
(pF)
Rfreq
(kΩ)
1.2 2.2 12.1 26.1 330 220 174
2.5 2.2 30 14.3 549 220 348
3.3 2.2 40.2 12.7 698 220 475
