PIC12F609-I/PQTP MICROCHIP [Microchip Technology], PIC12F609-I/PQTP Datasheet - Page 113

• Manufacturer Part Number: PIC12F609-I/PQTP
• Description: 8-Pin Flash-Based, 8-Bit CMOS Microcontrollers
• Manufacturer: MICROCHIP [Microchip Technology]

12.0
The PIC12HV609/HV615 includes a permanent
internal 5 volt (nominal) shunt regulator in parallel with
the V
voltage
unregulated supply. All external devices connected
directly to the V
voltage and contribute to the total V
(I
12.1
A shunt regulator generates a specific supply voltage
by creating a voltage drop across a pass resistor R
The voltage at the V
monitored and compared to an internal voltage refer-
ence. The current through the resistor is then adjusted,
based on the result of the comparison, to produce a
voltage drop equal to the difference between the supply
voltage V
See Figure 12-1 for voltage regulator schematic.
FIGURE 12-1:
© 2006 Microchip Technology Inc.
LOAD
C
I
SUPPLY
BYPASS
DD
).
pin. This eliminates the need for an external
VOLTAGE REGULATOR
Regulator Operation
regulator
UNREG
V
UNREG
R
SER
I
DD
SHUNT
and the V
pin will share the regulated supply
in
DD
VOLTAGE REGULATOR
systems
pin of the microcontroller is
DD
of the microcontroller.
Device
Feedback
sourced
DD
supply current
I
LOAD
PIC12F609/615/12HV609/615
by
V
V
DD
SS
SER
Preliminary
an
.
An external current limiting resistor, R
between the unregulated supply, V
pin, drops the difference in voltage between V
and V
defined by Equation 12-1.
EQUATION 12-1:
12.2
The supply voltage V
constant. Therefore, the current range of the regulator
is limited. Selecting a value for R
three factors into consideration.
Since the regulator uses the band gap voltage as the
regulated voltage reference, this voltage reference is
permanently enabled in the PIC12HV609/HV615
device.
The shunt regulator will still consume current when
below operating voltage range for the shunt regulator.
12.3
For more information on using the shunt regulator and
managing current load, see Application Note AN1035,
“Designing with HV Microcontrollers” (DS01035).
Where:
R
R
VU
VU
V
I
1.05
0.95
LOAD
DD
MAX
MIN
MIN
MAX
DD
. R
Regulator Considerations
Design Considerations
= maximum value of R
= minimum value of R
= minimum value of V
= maximum value of V
= regulated voltage (5V nominal)
= maximum expected load current in mA
= compensation for +5% tolerance of R
= compensation for -5% tolerance of R
R
R
SER
including I/O pin currents and external
circuits connected to V
MAX
MIN
must be between R
=
=
1.05 • (4
UNREG
R
0.95 • (50
(VU
(VU
SER
MAX
MIN
M
LIMITING RESISTOR
and load current are not
A + I
- 5V)
- 5V)
UNREG
M
SER
UNREG
SER
A)
SER
UNREG
LOAD
DD
DS41302A-page 111
(ohms)
MAX
(ohms)
.
must take these
)
, and the V
SER
and R
, located
MIN
UNREG
SER
SER
DD
as