PIC16F87-I/SS Microchip Technology, PIC16F87-I/SS Datasheet - Page 119

• Manufacturer Part Number: PIC16F87-I/SS
• Description: IC MCU FLASH 4KX14 EEPROM 20SSOP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F87-I/SS

• Program Memory Type: FLASH
• Program Memory Size: 7KB (4K x 14)
• Package / Case: 20-SSOP
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Eeprom Size: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 368 B
• Interface Type: SSP/USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 16
• Number Of Timers: 3
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM163014
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT20SS-1 - SOCKET TRANSITION 18DIP 20SSOPAC164307 - MODULE SKT FOR PM3 28SSOP
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

12.1
For the A/D converter to meet its specified accuracy,
the charge holding capacitor (C
to fully charge to the input channel voltage level. The
analog input model is shown in Figure 12-2. The
source impedance (R
switch (R
required to charge the capacitor C
switch (R
(V
mended impedance for analog sources is 2.5 k .
As the impedance is decreased, the acquisition time
EQUATION 12-1:
FIGURE 12-2:
 2003 Microchip Technology Inc.
T
T
T
DD
ACQ
C
ACQ
Note 1: The reference voltage (V
), see Figure 12-2. The maximum recom-
2: The charge holding capacitor (C
3: The maximum recommended impedance for analog sources is 10 k . This is required to meet the pin
4: After a conversion has completed, a 2.0 T
A/D Acquisition Requirements
SS
SS
=
=
=
=
=
=
=
=
) impedance varies over the device voltage
leakage specification.
During this time, the holding capacitor is not connected to the selected A/D input channel.
) impedance directly affect the time
Amplifier Settling Time + Hold Capacitor Charging Time + Temperature Coefficient
T
2 s + T
C
-120 pF (1 k + 7 k + 10 k ) In(0.0004885)
16.47 s
2 s + 16.47 s + [(50°C – 25 C)(0.05 s/ C)
19.72 s
AMP
HOLD
Legend: C
+ T
(R
C
VA
C
ACQUISITION TIME
ANALOG INPUT MODEL
+ [(Temperature -25°C)(0.05 s/°C)]
IC
S
+ T
) and the internal sampling
Rs
+ R
V
I leakage
R
SS
C
COFF
PIN
T
IC
HOLD
SS
ANx
+ R
C
5 pF
HOLD
PIN
HOLD
S
= input capacitance
= threshold voltage
= leakage current at the pin due to
= interconnect resistance
= sampling switch
= sample/hold capacitance (from DAC)
) In(1/2047)
various junctions
) must be allowed
REF
. The sampling
) has no effect on the equation, since it cancels itself out.
HOLD
V
DD
V
V
) is not discharged after each conversion.
T
T
Preliminary
= 0.6V
= 0.6V
AD
delay must complete before acquisition can begin again.
I leakage
500 nA
may be decreased. After the analog input channel is
selected (changed), this acquisition must be done
before the conversion can be started.
To
Equation 12-1 may be used. This equation assumes
that 1/2 LSb error is used (1024 steps for the A/D). The
1/2 LSb error is the maximum error allowed for the A/D
to meet its specified resolution.
To calculate the minimum acquisition time, T
the
(DS33023).
R
IC
calculate
1k
PICmicro
V
DD
SS R
Sampling
Switch
6 V
5 V
4 V
3 V
2 V
®
SS
the
Mid-Range
Sampling Switch
5 6 7 8 9 10 11
PIC16F87/88
V
minimum
SS
C
= DAC capacitance
= 51.2 pF
(k )
HOLD
Reference
DS30487B-page 117
acquisition
ACQ
Manual
, see
time,