MC34704AEP Freescale Semiconductor, MC34704AEP Datasheet - Page 43

• Manufacturer Part Number: MC34704AEP
• Description: IC POWER MANAGEMENT 56-QFN
• Manufacturer: Freescale Semiconductor

Specifications of MC34704AEP

• Applications: Processor
• Current - Supply: 86mA
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 56-QFN
• Output Voltage: 5 V
• Input Voltage: 2.7 V to 5.5 V
• Switching Frequency: 750 KHz to 2 MHz
• Mounting Style: SMD/SMT
• Number Of Outputs: 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Compensating for boost operation:
• L: A boost power stage can be designed to operate in
stage is when the input voltage is equal to one half of the
output voltage, which results in the Maximum
• COUT: The three elements of output capacitor that
• R1 and RB:
desire value using a Vref=0.6V, select R1 between 10k and
100K and then calculate RB as follows:
Analog Integrated Circuit Device Data
Freescale Semiconductor
C
L
1. Define I
L
ESR
CCM for load currents above a certain level usually 5 to
15% of full load. The minimum value of inductor to
maintain CCM can be determined by using the following
procedure:
However the worst case condition for the boost power
contribute to its impedance and output voltage ripple are
the ESR, the ESL and the capacitance C. The minimum
capacitor value is approximately:
• Where
• Now calculate the maximum allowed ESR to reach the
These two resistors help to set the output voltage to the
min
OUT
min
15% of full load:
desired
≥
≥
≤
≥
Vo D
------------------------------------------ -
Vo T ( )
--------------- -
16I
-------------------------------------------- -
⎛
⎝
Io
---------------------------- -
FswΔVo
---------------------- -
1
max
( ) 1
Io
–
Δ
OB
OB
Δ
VO
D
max
2I
VO
(
D
ΔVo
max
as the minimum current to maintain CCM as
OB
max
r
–
r
is the desired output voltage ripple.
:
r
D
r
+
)
I
2
OB
T
⎞
⎠
Δ
[H]
[H]
[F]
I
L
, then:
[Ω]
• Compensation network. (C1,C2,C3, R2, R3)
frequencies referring to the plant are:
charge of canceling some of these poles and zeros to
achieve stability in the system. The following poles and
zeroes frequencies are provided by the type 3 compensation:
F
F
F
RB
1. Output LC filter cutoff frequency (F
D′
2. Cutoff frequency due to capacitor ESR:
3. The right plane zero frequency:
RHP
4. Crossover frequency (or bandwidth): select this
F
F
For compensating a boost converter, 4 important
• Where D’
The Type 3 external compensation network will be in
PO
P1
ESR
BW
LC
min
by:
frequency as far away form the RHP
possible:
=
=
=
«
Z
=
=
F
----------------------- -
------------- -
V
=
F
RHP
--------------- -
=
------------------------- -
2π
Vo
ESR
REF
--------------------------------------- -
2π C
BW
---------------------- -
Vout
6
R1
(
---------------------------------------- -
D′
Vin
D′
LC
(
Z
–
min
min
min
OUT
min
OUT
max
1
1
2πL
is the minimum off time percentage given
)
F
2
F
)ESR
R
Z1
2P
LOAD
=
=
FUNCTIONAL DEVICE OPERATION
0.9F
F
---------- -
SW
2
LC
COMPONENT CALCULATION
[Ω]
F
LC
22
Z
[Hz]
):
as much as
=
[Hz]
[Hz]
[Hz]
1.1F
LC
34704
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