PIC18F87K90-I/PTRSL Microchip Technology, PIC18F87K90-I/PTRSL Datasheet - Page 381

• Manufacturer Part Number: PIC18F87K90-I/PTRSL
• Description: MCU PIC 128K FLASH XLP 80TQFP
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 18Fr

Specifications of PIC18F87K90-I/PTRSL

• Core Size: 8-Bit
• Program Memory Size: 128KB (64K x 16)
• Core Processor: PIC
• Speed: 64MHz
• Connectivity: I²C, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 69
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 24x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 80-TFQFP
• Controller Family/series: PIC18
• Eeprom Memory Size: 1024Byte
• Ram Memory Size: 4096Byte
• Cpu Speed: 16MIPS
• No. Of Timers: 11
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: I2C, SPI
• Maximum Clock Frequency: 64 MHz
• Number Of Timers: 11
• Operating Supply Voltage: 1.8 V to 5.5 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 12 bit, 24 Channel
• A/d Bit Size: 12 bit
• A/d Channels Available: 24
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

23.3
For the A/D Converter to meet its specified accuracy, the
charge holding capacitor (C
fully charge to the input channel voltage level. The
analog input model is shown in Figure 23-5. The source
impedance (R
impedance directly affect the time required to charge the
capacitor C
varies over the device voltage (V
The source impedance affects the offset voltage at the
analog input (due to pin leakage current). The maxi-
mum recommended impedance for analog sources
is 2.5 k . After the analog input channel is selected or
changed, the channel must be sampled for at least the
minimum acquisition time before starting a conversion.
EQUATION 23-1:
EQUATION 23-2:
EQUATION 23-3:
 2010 Microchip Technology Inc.
T
V
or
T
T
T
T
Temperature coefficient is only required for temperatures > 25C. Below 25C, T
T
T
ACQ
Note:
C
ACQ
AMP
COFF
C
ACQ
HOLD
=
=
A/D Acquisition Requirements
=
=
=
=
=
=
=
HOLD
When the conversion is started, the
holding capacitor is disconnected from the
input pin.
Amplifier Settling Time + Holding Capacitor Charging Time + Temperature Coefficient
T
S
AMP
) and the internal sampling switch (R
T
0.2 s
(Temp – 25C)(0.02 s/C)
(85C – 25C)(0.02 s/C)
1.2 s
-(C
-(25 pF) (1 k + 2 k + 2.5 k) ln(0.0004883) s
1.05 s
0.2 s + 1.05 s + 1.2 s
2.45 s
. The sampling switch (R
(V
-(C
AMP
REF
HOLD
+ T
HOLD
+ T
C
– (V
ACQUISITION TIME
A/D MINIMUM CHARGING TIME
CALCULATING THE MINIMUM REQUIRED ACQUISITION TIME
+ T
)(R
)(R
C
+ T
COFF
REF
IC
IC
HOLD
+ R
COFF
/2048)) • (1 – e
+ R
DD
SS
) must be allowed to
SS
).
+ R
+ R
S
S
) ln(1/2048) s
SS
) ln(1/2048)
) impedance
(-T
C
/C
HOLD
Preliminary
SS
(R
)
IC
+ R
SS
PIC18F87K90 FAMILY
+ R
To
Equation 23-1 can be used. This equation assumes
that 1/2 LSb error is used (1,024 steps for the A/D). The
1/2 LSb error is the maximum error allowed for the A/D
to meet its specified resolution.
Equation 23-3 shows the calculation of the minimum
required acquisition time, T
based
assumptions:
S
• C
• Rs
• Conversion Error 
• V
• Temperature
))
)
DD
HOLD
calculate
on
COFF
the
= 0 ms.
the
following
=
=
=
=
minimum
ACQ
25 pF
2.5 k 
1/2 LSb
3V  Rss = 2 k 
85  C (system max.)
. This calculation is
application
DS39957B-page 381
acquisition
system
time,