PIC17C756A-33/L Microchip Technology Inc., PIC17C756A-33/L Datasheet - Page 31

• Manufacturer Part Number: PIC17C756A-33/L
• Description: 68 PIN, 32 KB OTP, 902 RAM, 50 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC17C756A-33/L

• A/d Inputs: 12-Channel, 10-Bit
• Cpu Speed: 8.25 MIPS
• Eeprom Memory: 0 Bytes
• Input Output: 52
• Interface: I2C/SPI/USART
• Memory Type: OTP
• Number Of Bits: 8
• Package Type: 68-pin PLCC
• Programmable Memory: 32K Bytes
• Ram Size: 902 Bytes
• Speed: 16 MHz
• Timers: 2-8-bit, 2-16-bit
• Voltage, Range: 3-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part

5.1.5
PIC17C7XX devices have on-chip Brown-out Reset
circuitry. This circuitry places the device into a RESET
when the device voltage falls below a trip point (BV
This ensures that the device does not continue pro-
gram execution outside the valid operation range of the
device. Brown-out Resets are typically used in AC line
applications, or large battery applications, where large
loads may be switched in (such as automotive).
The BODEN configuration bit can disable (if clear/
programmed), or enable (if set) the Brown-out Reset
circuitry. If V
paramter #D005 in electrical specification section), for
greater than parameter #35, the Brown-out situation
will reset the chip. A RESET is not guaranteed to occur
if V
chip will remain in Brown-out Reset until V
above BV
up Timer will then be invoked. This will keep the chip in
RESET the greater of 96 ms and 1024 T
drops below BV
Start-up Timer is running, the chip will go back into a
Brown-out Reset. The Power-up Timer/Oscillator Start-
up Timer will be initialized. Once V
BV
will start their time delays. Figure 5-10 shows typical
Brown-out situations.
In some applications, the Brown-out Reset trip point of
the device may not be at the desired level. Figure 5-8
and Figure 5-9 are two examples of external circuitry
FIGURE 5-10:
Note:
2000 Microchip Technology Inc.
DD
DD
, the Power-up Timer/Oscillator Start-up Timer
falls below BV
DD
Before using the on-chip Brown-out for a
voltage
review the electrical specifications to
ensure that they meet your requirements.
BROWN-OUT RESET (BOR)
. The Power-up Timer and Oscillator Start-
DD
Internal
RESET
Internal
RESET
Internal
RESET
DD
falls below BV
V
V
V
while the Power-up Timer/Oscillator
DD
DD
DD
DD
supervisory
BROWN-OUT SITUATIONS
for less than paramter #35. The
DD
function,
(typically 4.0 V,
DD
rises above
OSC
DD
. If V
please
rises
DD
DD
).
< 96 ms
Greater of 96 ms
that may be implemented. Each needs to be evaluated
to determine if they match the requirements of the
application.
FIGURE 5-8:
FIGURE 5-9:
and 1024 T
Greater of 96 ms
Greater of 96 ms
This circuit will activate RESET when V
(Vz + 0.7V) where Vz = Zener voltage.
This brown-out circuit is less expensive, albeit less
accurate. Transistor Q1 turns off when V
certain level such that:
and 1024 T
and 1024 T
33k
R1
R2
V
OSC
DD
V
DD
V
DD
OSC
OSC
10k
40 k
•
40 k
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 1
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 2
R1 + R2
PIC17C7XX
R1
Q1
BV
BV
BV
BV
BV
BV
DD
DD
DD
DD
DD
DD
MCLR
Max.
Min.
V
PIC17CXXX
Max.
Min.
Max.
Min.
MCLR
= 0.7V
PIC17CXXX
V
DD
DD
DS30289B-page 31
DD
DD
goes below
is below a