MAX5099ATJ+ Maxim Integrated Products, MAX5099ATJ+ Datasheet - Page 22

• Manufacturer Part Number: MAX5099ATJ+
• Description: IC CONV BUCK SYNC DL 32TQFN-EP
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX5099ATJ+

• Internal Switch(s): Both
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.8 ~ 17.1 V
• Current - Output: 1A, 2A
• Frequency - Switching: 200kHz ~ 2.2MHz
• Voltage - Input: 4.5 ~ 19 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 32-TQFN Exposed Pad
• Power - Output: 2.76W
• Output Voltage: 5.2 V
• Output Current: 2 A
• Input Voltage: 5.2 V to 19 V
• Supply Current: 4.2 mA
• Switching Frequency: 1.9 MHz
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

If the output capacitor used is a low-ESR ceramic type,
the ESR frequency is usually far away from the targeted
unity crossover frequency (f
compensation is recommended. Type III compensation
provides two-pole zero pairs. The locations of the zero
and poles should be such that the phase margin peaks
around f
or below the double pole to avoid the conditional stabil-
ity issue.
1) Select a crossover frequency:
2) Calculate the LC double-pole frequency, f
where
and R
4) Calculate C
5) Place a pole
6) Place a second zero, f
whichever is lower.
Dual, 2.2MHz, Automotive Synchronous Buck
Converter with 80V Load-Dump Protection
22
3) Place a zero
______________________________________________________________________________________
F
≥ 10kΩ.
C
. It is also important to place the two zeros at
C
I
=
I
f
for a target unity crossover frequency, f
2π
LC
C
R
f
P
F
I
1
R
×
=
=
=
1
=
f
Z
f
C
=
2π
2π
1
2
2
π
×
2
=
π
f
SW
×
×
π
L
×
×
2
OUT
×
f
0 75
R
ZERO ESR
π
V
1
L
≤
.
f
Procedure 2 (See Figure 4)
I
IN
Z
×
1
OUT
×
Z2
2
f
R
SW
20
1
C
×
×
1
1
C
1
×
×
F
,
, at 0.2 x f
). In this case, Type III
R
C
I
C
f
×
LC
×
at f
F
OUT
I
C
C
−
F
×
×
R
OUT
ZERO ESR
I
R
C
at
×
F
I
V
0 75
OSC
,
.
C
LC
×
.
or at f
:
f
LC
.
LC
C
.
,
7) Place a second pole at 1/2 the switching frequency.
The boost converter compensation gets complicated
due to the presence of a right-half-plane zero
f
phase while adding positive (+1) slope to the gain
curve. It is important to drop the gain significantly below
unity before the RHP frequency. Use the following pro-
cedure to calculate the compensation components:
1) Calculate the LC double-pole frequency, f
the right-half-plane-zero frequency.
where
Target the unity-gain crossover frequency for:
Figure 4. Type III Compensation Network
ZERO,RHP
. The right-half-plane zero causes a drop in
C
C
R
I
CF
I
f
f
LC
ZERO RHP
=
R1
R2
(
R
V
2
=
OUT
(
π
MIN
,
2π
f
C
×
D
Boost Converter Compensation
0 5
≤
×
=
)
V
.
REF
=
1
f
=
FB_
ZERO RHP
×
L
−
I
(
OUT MAX
OUT
1
R
f
V
1
SW
2
F
-
+
V
−
OUT
V
C
5
C
−
g
π
CF
IN
OUT
,
D R
M
D
F
(
×
×
)
×
2
L
R
C
C
OUT
F
F
(
OUT
MIN
)
×
C
)
COMP_
F
)
−
1
LC
, and