MC34704AEP Freescale Semiconductor, MC34704AEP Datasheet - Page 39

• 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

F
CONFIGURATION
REG1(VG) thru REG5, and this can be changed by applying
a voltage between 0 to 2.5 V to the FREQ pin. If the FREQ
pin is left unconnected, the 34704 starts up with a default
frequency of 750 KHz. To configure the F
resistors voltage divider from VDDI to ground to set the
voltage on the FREQ pin as indicated bellow:
Notes
the regulators through programming the SS pin with an
external resistor divider connected between VDDI and AGND
as follows:
Analog Integrated Circuit Device Data
Freescale Semiconductor
27.
SW1
The 34704 uses F
Initially at power up, the soft start time will be set for all of
V
FREQ
RF2
AND GENERAL SOFT START
RF1
If an external voltage is used, F
device startup.
Ratio
13/32
17/32
21/32
VDDI
9/32
0
VDDI
FREQ
GND
SW1
as the switching frequency for
V
FREQ
RF1, RF2 tolerance ±1.0%
SW1
=
can only be set during
V
DDI
[KHz]
SW1
F
1000
1250
1500
1750
2000
750
SW1
⎛
⎝
, use a 2
----------------------------- -
RF1
COMPONENT CALCULATION
RF2
+
RF2
⎞
⎠
REGULATORS POWER STAGE AND
COMPENSATION CALCULATION
Regulator 1 and 6 (Synchronous Boost - internally
compensated - REG1 is VG supply).
Maximum current of 500 mA while REG6 is set to 15 V at
60 mA (on the 34704B, REG1 does not exist but similar
circuitry is used to provide the internal VG voltage). They do
not need an external compensation network, thus, the only
components that need to be calculated are:
• R1 and RB (Only REG6): These two resistors help to set
• L: A boost power stage can be designed to operate in
RB
REG1 is a Synchronous Boost converter set to 5.0 V and
the output 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:
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:
RSS1
RSS2
I
DD
V
=
SS
max = 100μΑ
--------------------- -
----------- -
Vref
Vo
R1
Ratio
11/32
19/32
VDDI
–
0
1
VDDI
SS
GND
FUNCTIONAL DEVICE OPERATION
V
SS
RSS1, RSS2 tolerance ±1.0%
COMPONENT CALCULATION
=
Soft Start timing
V
DDI
⎛
⎝
[ms]
32.0
0.5
2.0
8.0
--------------------------------------- -
RSS1
RSS2
+
[Ω]
RSS2
34704
⎞
⎠
39