PIC16F785-I/SO Microchip Technology, PIC16F785-I/SO Datasheet - Page 88

• Manufacturer Part Number: PIC16F785-I/SO
• Description: IC PIC MCU FLASH 2KX14 20SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F785-I/SO

• Program Memory Type: FLASH
• Program Memory Size: 3.5KB (2K x 14)
• Package / Case: 20-SOIC (7.5mm Width)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 17
• Eeprom Size: 256 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 128 B
• Interface Type: RS- 232/USB
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 17
• 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, DV164120, DM163029
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 14-ch x 10-bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT20SO1-1 - SOCKET TRANS ICE 20DIP TO 20SOICXLT18SO-1 - SOCKET TRANSITION 18SOIC 300MILAC162060 - HEADER INTRFC MPLAB ICD2 20PINAC164039 - MODULE SKT PROMATE II 20DIP/SOIC
• Connectivity: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC16F785/HV785
12.2
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 12-4. The
source impedance (R
switch (R
required to charge the capacitor C
switch (R
(V
mended impedance for analog sources is 10 kΩ. As
the impedance is decreased, the acquisition time may
be decreased. After the analog input channel is
selected (changed), this acquisition must be done
before the conversion can be started.
EQUATION 12-1:
DS41249E-page 86
DD
Note 1: The reference voltage (V
), see Figure 12-4. The maximum recom-
The value for Tc can be approximated with the following equations:
Solving for Tc:
Therefore:
Assumptions:
2: The charge holding capacitor (C
3: The maximum recommended impedance for analog sources is 10 kΩ. This is required to meet the pin
A/D Acquisition Requirements
SS
SS
) impedance varies over the device voltage
V
Tacq
leakage specification.
) impedance directly affect the time
V
V
T
AP P LIED
T
A PP LIED
ACQ
A PP LIE D
c
=
=
=
=
=
=
=
=
5µs
Temperature
–
–
7.62
ACQUISITION TIME EXAMPLE
1.37
S
10pF 1k
⎛
⎝
C
Amplifier Settling Time
T
5µs
) and the internal sampling
⎛
⎜
⎝
⎛
⎜
⎝
1
AMP
HOLD
1 e
1 e
+
µs
µs
–
–
+
–
1.37µs
(
----------- -
2047
+
Tc
(
HOLD
1
Ric
–
--------- -
–
-------- -
RC
RC
Ω
Tc
T
Tc
+
HOLD
C
+
⎞
⎠
⎞
⎟
⎠
⎞
⎟
⎠
+
+
+
) must be allowed
[
REF
(
7k
=
Temperature - 25°C
T
Rss
[
=
=
=
. The sampling
(
COFF
Ω
50°C- 25°C
) has no effect on the equation, since it cancels itself out.
50°C and external impedance of 10k
V
V
V
+
+
C HOLD
CHOLD
AP P LI ED
HOLD
10k
Rs
) ln(1/2047)
+
Ω
) is not discharged after each conversion.
)
Hold Capacitor Charging Time
ln(0.0004885)
) 0.05µs/°C
⎛
⎝
(
1
–
) 0.05µs/°C
----------- -
2047
(
1
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.
)
⎞
⎠
]
calculate
;[2] Vchold charge response to Vapplied
;Combining [1] and [2]
;[1] Vchold charged to within 1/2 lsb
)
]
Ω
the
5.0V V
+
Temperature Coefficient
minimum
© 2008 Microchip Technology Inc.
DD
acquisition
time,