PIC16F54-I/SS Microchip Technology, PIC16F54-I/SS Datasheet - Page 29

• Manufacturer Part Number: PIC16F54-I/SS
• Description: IC MCU FLASH 512X12 20SSOP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F54-I/SS

• Core Size: 8-Bit
• Program Memory Size: 768B (512 x 12)
• Core Processor: PIC
• Speed: 20MHz
• Peripherals: POR, WDT
• Number Of I /o: 12
• Program Memory Type: FLASH
• Ram Size: 25 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-SSOP
• Controller Family/series: PIC16F
• No. Of I/o's: 12
• Ram Memory Size: 25Byte
• Cpu Speed: 20MHz
• No. Of Timers: 1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AC164307 - MODULE SKT FOR PM3 28SSOPAC164014 - MODULE SKT PROMATEII 44PQFP
• Eeprom Size: -
• Data Converters: -
• Connectivity: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

5.2
The Device Reset Timer (DRT) provides an 18 ms
nominal time-out on Reset regardless of Oscillator
mode used. The DRT operates on an internal RC
oscillator. The processor is kept in Reset as long as the
DRT is active. The DRT delay allows V
V
Oscillator circuits based on crystals or ceramic resona-
tors require a certain time after power-up to establish a
stable oscillation. The on-chip DRT keeps the device in
a Reset condition for approximately 18 ms after the
voltage on the MCLR/V
(V
the MCLR input are not required in most cases,
allowing for savings in cost-sensitive and/or space
restricted applications.
The device Reset time delay will vary from chip-to-chip
due to V
AC parameters for details.
The DRT will also be triggered upon a Watchdog Timer
time-out. This is particularly important for applications
using the WDT to wake the PIC16F5X from Sleep
mode automatically.
5.3
A brown-out is a condition where device power (V
dips below its minimum value, but not to zero, and then
recovers. The device should be reset in the event of a
brown-out.
To reset PIC16F5X devices when a brown-out occurs,
external brown-out protection circuits may be built, as
shown in Figure 5-6, Figure 5-7 and Figure 5-8.
FIGURE 5-6:
 2004 Microchip Technology Inc.
DD
IH
Note:
) level. Thus, external RC networks connected to
min. and for the oscillator to stabilize.
33k
V
Device Reset Timer (DRT)
DD
Reset on Brown-Out
DD
, temperature and process variation. See
This circuit will activate Reset when V
goes below Vz + 0.7V (where Vz = Zener
voltage).
10k
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 1
PP
Q1
40k
pin has reached a logic high
MCLR
PIC16F5X
V
DD
DD
to rise above
DD
Preliminary
DD
)
FIGURE 5-7:
FIGURE 5-8:
This brown-out circuit is less expensive, although
less accurate. Transistor Q1 turns off when V
below a certain level such that:
This
Microchip Technology’s MCP809 microcontroller
supervisor. The MCP8XX and MCP1XX families
of supervisors provide push-pull and open
collector outputs with both “active-high and
active-low” Reset pins. There are 7 different trip
point selections to accommodate 5V and 3V
systems.
Vss
MCP809
V
brown-out
DD
R1
R2
V
DD
RST
V
DD
V
DD
capacitor
•
bypass
protection
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 2
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 3
R1 + R2
R1
Q1
PIC16F5X
40k
= 0.7V
PIC16F5X
circuit
MCLR
PIC16F5X
V
MCLR
V
DS41213B-page 27
DD
DD
employs
DD
is