mpc5644a Freescale Semiconductor, Inc, mpc5644a Datasheet - Page 83

• Manufacturer Part Number: mpc5644a
• Description: Mpc5644a Microcontroller Data Sheet
• Manufacturer: Freescale Semiconductor, Inc

3.6.2
In designs where the MPC5644A microcontroller’s internal regulators are used, a ballast is required for generation of the 1.2 V
internal supply. No ballast is required when an external 1.2 V supply is used.
3.6.3
The following NPN transistors are recommended for use with the on-chip voltage regulator controller: ON Semiconductor
BCP68T1 or NJD2873 as well as Philips Semiconductor
connected to the same voltage supply source as the output stage of the regulator.
Freescale Semiconductor
The resistor may or may not be
required. This depends on the
allowable power dissipation of
the npn bypass transistor
device. The resistor may be
used to limit the in-rush current
at power on.
4
Mandatory decoupling
capacitor network
The bypass transistor
MUST be operated out
of saturation region.
Values are based on I
Figure 8. Core voltage regulator controller external components preferred configuration
Regulator Example
Recommended power transistors
1
Symbol
I
VCE
h
CMaxDC
Adjust resistor at bipolar transistor collector for 3.3 V/5.0 V to avoid VCE < VCE
FE
V
P
BE
D
()
SAT
DC current gain (Beta)
Absolute minimum power dissipation
Minimum peak collector current
Collector-to-emitter saturation voltage
Base-to-emitter voltage
DD
Table 17. Recommended operating characteristics
from high-use applications as explained in the I
Preliminary—Subject to Change Without Notice
MPC5644A Microcontroller Data Sheet, Rev. 4
6.8 F
1.1–5.6 
Parameter
4  6.8 F
TM
BCP68. The collector of the external transistor is preferably
4  220 nF
10 F
VRCCTL capacitor and resistor is required
V
V
DDREG
15 
RCCTL
680 nF
DD
(1.5 preferred)
V
V
DD
SS
Electrical Specification.
60 – 550
> 200
Value
>1.0
>0.7
1.0
1
MCU
SAT
Electrical characteristics
Unit
mV
—
W
A
V
.
TM
83