PIC17C756-16/SP Microchip Technology, PIC17C756-16/SP Datasheet - Page 22

• Manufacturer Part Number: PIC17C756-16/SP
• Description: MICRO CTRL 16K MEMORY OTP 64SDIP
• Manufacturer: Microchip Technology
• Series: PIC® 17Cr

Specifications of PIC17C756-16/SP

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 50
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: OTP
• Ram Size: 902 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 6 V
• Data Converters: A/D 12x10b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 64-SDIP (0.750", 19.05mm)
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Eeprom Size: -
• Other names: PIC17C756-16/P

5.1
5.1.1
The Power-on Reset circuit holds the device in reset
until V
2.3V). The devices produce an internal reset for both
rising and falling V
just tie the MCLR/V
to V
usually needed to create Power-on Reset. A minimum
rise time for V
tions for details.
Figure 5-2 and Figure 5-3 show two possible POR cir-
cuits.
FIGURE 5-2:
FIGURE 5-3:
DS30264A-page 22
Note 1: An external Power-on Reset circuit is
DD
DD
. This will eliminate external RC components
V
2: R < 40 k is recommended to ensure
3: R1 = 100 to 1 k will limit any current
DD
Power-on Reset (POR), Power-up
Timer (PWRT), Oscillator Start-up
Timer (OST), and Brown-out Reset
(BOR)
POWER-ON RESET (POR)
is above the trip point (in the range of 1.4V -
D
required only if V
slow. The diode D helps discharge the
capacitor quickly when V
down.
that the voltage drop across R does not
exceed 0.2V (max. leakage current spec.
on the MCLR/V
voltage drop will degrade V
MCLR/V
flowing into MCLR from external capaci-
tor C in the event of MCLR/V
breakdown due to Electrostatic Dis-
charge (ESD) or Electrical Overstress
(EOS).
DD
V
DD
R
is required. See Electrical Specifica-
USING ON-CHIP POR
EXTERNAL POWER-ON
RESET CIRCUIT (FOR SLOW
V
C
DD
PP
DD
PP
. To take advantage of the POR,
pin directly (or through a resistor)
pin.
POWER-UP)
V
R1
DD
PP
DD
pin is 5 A). A larger
power-up time is too
PIC17CXXX
PIC17CXXX
V
MCLR
MCLR
DD
DD
IH
powers
PP
level on the
pin
Preliminary
5.1.2
The Power-up Timer provides a fixed 96 ms time-out
(nominal) on power-up. This occurs from the rising
edge of the POR signal and after the first rising edge of
MCLR (detected high). The Power-up Timer operates
on an internal RC oscillator. The chip is kept in RESET
as long as the PWRT is active. In most cases the
PWRT delay allows V
The power-up time delay will vary from chip to chip and
with V
details.
5.1.3
The Oscillator Start-up Timer (OST) provides a 1024
oscillator cycle (1024T
detected high or a wake-up from SLEEP event occurs.
The OST time-out is invoked only for XT and LF oscil-
lator modes on a Power-on Reset or a Wake-up from
SLEEP.
The OST counts the oscillator pulses on the
OSC1/CLKIN pin. The counter only starts incrementing
after the amplitude of the signal reaches the oscillator
input thresholds. This delay allows the crystal oscillator
or resonator to stabilize before the device exits reset.
The length of the time-out is a function of the crys-
tal/resonator frequency.
Figure 5-4 shows the operation of the OST circuit. In
this figure the oscillator is of such a low frequency that
OST time out occurs after the power-up timer time-out.
FIGURE 5-4:
This figure shows in greater detail the timings involved
with the oscillator start-up timer. In this example the low
frequency crystal start-up time is larger than power-up
time (T
Tosc1 = time for the crystal oscillator to react to an oscil-
lation level detectable by the Oscillator Start-up Timer
(ost).
T
INTERNAL RESET
PWRT TIME_OUT
OST
OST TIME_OUT
DD
= 1024T
PWRT
POWER-UP TIMER (PWRT)
OSCILLATOR START-UP TIMER (OST)
and temperature. See DC parameters for
OSC2
MCLR
).
V
OSC
DD
OSCILLATOR START-UP
TIME
.
POR or BOR Trip Point
T
DD
OSC
to rise to an acceptable level.
OSC
1
1997 Microchip Technology Inc.
) delay after MCLR is
T
PWRT
T
OST