MC34704AEP Freescale Semiconductor, MC34704AEP Datasheet - Page 41

• 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

step during the current rising time and is define as:
indistinctly, the first one indicates the output voltage ripple,
while the second one is the maximum output voltage
overshoot (transient response).
ESR
Analog Integrated Circuit Device Data
Freescale Semiconductor
ΔIostep
C
dtI
1. First calculate the dt_I (inductor current rising time)
2. Then the output capacitor can be chosen as follow:
OUT
3. Finally find the maximum allowed ESR to allow the
Where the parameter
• Where
NOTE: Do not use the parameters
=
max
given by:
overshoot expressed as a percentage of the output
voltage, typically from 3 to 5% of Vo.
desired transient response:
≤
--------------------- -
ΔIostep
Io
Io
----------------------
ΔVo
max
=
=
max
⎛
⎝
ΔVo
--------------------------------------
Δ
Vo 1
max
T
D
------------- -
Fsw
dtI
VO
max
(
r
max
(
Fsw
⎞ Vin
⎠
–
⎛
⎝
D
-------------------------------
is the maximum allowed transient
min
) L ( )
Δ
min
)
Io_step is the maximum current
L
–
Vo
⎞
⎠
Δ
VO
r
and
[A]
[s]
Δ
[Ω]
VO
[A]
max
• R1 and RB: These two resistors help to set the output
• Compensation network. (C1,C2,C3, R2, R3): For
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
RB
F
1. Output LC filter cutoff frequency (F
2. Cutoff frequency due to capacitor ESR:
3. Crossover frequency (or bandwidth):
voltage to the desire value using a Vref=0.6 V, select R1
between 10 k and 100 K and then calculate RB as follows:
compensating a buck converter, 3 important frequencies
referring to the plant are:
ESR
The Type 3 external compensation network will be in
BW
LC
=
=
=
=
--------------------- -
----------- -
Vref
------------------------- -
2π
Vo
F
---------- -
--------------------------------------- -
2π C
10
SW
R1
LC
(
1
–
OUT
OUT
1
1
)ESR
FUNCTIONAL DEVICE OPERATION
COMPONENT CALCULATION
LC
):
[Hz]
[Hz]
[Hz]
[Ω]
34704
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