MIC24420 Datasheet, PDF (22/34 Pages) Micrel Semiconductor – 2.5A Dual Output PWM Synchronous Buck Regulator IC

Micrel, Inc.
The general form of the feedforward circuit is shown
below.
⎜⎛1 + ^s ⎟⎞
H(s) = ^R2 × ^{⎝ ωz3 âŽ} 
R1 + R2
⎜⎜⎝⎛^{1 +}
s
ωp3
⎟⎟⎠⎞
Where:
fz3 =
1
2 × π × R1× C1
fp3 =
1
2 × π × C1× ⎜⎛ ^{R1× R2} ⎟⎞
⎝ ^{R1 + R2} ⎠
The total open loop transfer function is:
T(s) = Gea(s) × Gmod × Gfilter(s) × H(s)
The following tables list the recommended values of
compensation and filter components for different output
voltages. The output capacitors are ceramic.
MIC24420/MIC24421
V_OUT R1 R2
1.0V 1k 2.32k
1.2V 1k 1.4k
1.4V 1k 1k
1.8V 1k 634
2.5V 1k 383
3.3V 1k 274
5.0V 1k 162
C7/8
220pF
220pF
220pF
150pF
150pF
150pF
150pF
MIC24420
C16/17 R22/23
3.3nF
NF
3.3nF
NF
3.3nF
NF
4.7nF
NF
10nF
NF
10nF
NF
10nF
NF
C29/30
NF
NF
NF
NF
NF
NF
NF
L_MIN
10µH
10µH
10µH
10µH
10µH
10µH
10µH
Co_MIN
47µF
47µF
47µF
47µF
47µF
47µF
47µF
V_OUT R1
1.0V 1k
1.2V 1k
1.4V 1k
1.8V 1k
2.5V 1k
3.3V 1k
5.0V 1k
R2
2.32k
1.4k
1k
634
383
274
162
C7/8
1000pF
1000pF
1000pF
1000pF
1000pF
1000pF
1000pF
MIC24421
C16/17 R22/23
22nF
22k
22nF
22k
22nF
22k
22nF
22k
22nF
22k
22nF
22k
22nF
22k
C29/30
100nF
100nF
100nF
100nF
100nF
100nF
100nF
L_MIN
22µH
22µH
22µH
22µH
22µH
22µH
22µH
Co_MIN
100µF
100µF
100µF
100µF
100µF
100µF
100µF
June 2012
22
M9999-062012-C