PIC18F2550T-I/SO Microchip Technology, PIC18F2550T-I/SO Datasheet - Page 272

• Manufacturer Part Number: PIC18F2550T-I/SO
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,SOP,28PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2550T-I/SO

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: I²C, SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 24
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 10x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-SOIC (7.5mm Width)
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 2 KB
• Interface Type: SPI, I2C, EAUSART
• Maximum Clock Frequency: 48 MHz
• Number Of Programmable I/os: 24
• Number Of Timers: 4
• 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, 52712-325, EWPIC18
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, ICE4000, DM163025, DV164136
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 10 Channel
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: I3-DB18F4550 - BOARD DAUGHTER ICEPIC3DM163025 - PIC DEM FULL SPEED USB DEMO BRD
• Lead Free Status / Rohs Status: Details

PIC18F2455/2550/4455/4550
21.1
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 21-3. The
source impedance (R
switch (R
required to charge the capacitor C
switch (R
(V
at the analog input (due to pin leakage current). The
maximum recommended impedance for analog
sources is 2.5 kΩ. After the analog input channel is
selected (changed), the channel must be sampled for
at least the minimum acquisition time before starting a
conversion.
EQUATION 21-1:
EQUATION 21-2:
EQUATION 21-3:
DS39632E-page 270
T
V
or
T
T
T
T
Temperature coefficient is only required for temperatures > 25°C. Below 25°C, T
T
T
ACQ
DD
Note:
C
ACQ
AMP
COFF
C
ACQ
HOLD
). The source impedance affects the offset voltage
=
=
A/D Acquisition Requirements
SS
=
=
=
=
=
SS
=
=
) impedance varies over the device voltage
When the conversion is started, the
holding capacitor is disconnected from the
input pin.
Amplifier Settling Time + Holding Capacitor Charging Time + Temperature Coefficient
T
) impedance directly affect the time
AMP
T
0.2 μs
(Temp – 25°C)(0.02 μs/°C)
(85°C – 25°C)(0.02 μs/°C)
1.2 μs
-(C
-(25 pF) (1 kΩ + 2 kΩ + 2.5 kΩ) ln(0.0004883) μs
1.05 μs
0.2 μs + 1.05 μs + 1.2 μs
2.45 μs
(V
-(C
AMP
HOLD
+ T
REF
HOLD
+ T
C
– (V
ACQUISITION TIME
A/D MINIMUM CHARGING TIME
CALCULATING THE MINIMUM REQUIRED ACQUISITION TIME
S
+ T
)(R
C
) and the internal sampling
)(R
+ T
REF
COFF
IC
IC
+ R
COFF
/2048)) • (1 – e
+ R
HOLD
SS
SS
HOLD
+ R
+ R
) must be allowed
S
S
) ln(1/2048) μs
. The sampling
) ln(1/2048)
(-T
C
/C
HOLD
(R
IC
+ R
SS
+ R
S
To
Equation 21-1 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.
Example 21-3 shows the calculation of the minimum
required acquisition time T
based
assumptions:
C
Rs
Conversion Error
V
Temperature
))
HOLD
DD
)
calculate
on
COFF
the
= 0 μs.
the
=
=
≤
=
=
following
minimum
© 2009 Microchip Technology Inc.
25 pF
2.5 kΩ
1/2 LSb
5V → R
85°C (system max.)
ACQ
. This calculation is
SS
application
acquisition
= 2 kΩ
system
time,