PIC16F785-I/SO Microchip Technology, PIC16F785-I/SO Datasheet - Page 85

• 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

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 k . As
the impedance is decreased, the acquisition time may
EQUATION 12-1:
 2004 Microchip Technology Inc.
DD
Note 1: The reference voltage (V
Where C
Solving for T
Therefore:
), see Figure 12-4. 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
A/D Acquisition Requirements
SS
T
T
SS
ACQ
ACQ
V
V
V
) impedance varies over the device voltage
HOLD
leakage specification.
T
) impedance directly affect the time
AP P LIED
AP P LIED
AP P LIED
C
C
=
=
=
=
=
=
=
=
:
is charged to within 1/2 lsb:
–
2µ
4.67µ
Amplifier Settling Time
1.37
–
T
2µs
10pF 1k
C
S
AMP
ACQUISITION TIME EXAMPLE








S
HOLD
+
1
1 e
1 e
µs
) and the internal sampling
+
S
1.37µ
–
–
–
+
T
C
----------- -
2047
T
R
–
--------- -
–
-------- -
RC
+
RC
C
1
T
Tc
HOLD
IC
S
+
C
+
+






HOLD
+


7k
Temperature - 25°C 0.05µs/°C
T
) must be allowed
=
R
COFF
=
REF
=
50°C- 25°C 0.05µ
SS
. The sampling
+
V
V
) has no effect on the equation, since it cancels itself out.
V
+
A PP LIE D
CHOLD
10k
C HOLD
R
+
HOLD
S
Hold Capacitor Charging Time
ln(1/2047)
ln(0.0004885)
) is not discharged after each conversion.
Preliminary


1
–
----------- -
2047
S
/°C
1
be decreased. After the analog input channel is
selected (changed), this acquisition must be done
before the conversion can be started.
To calculate the minimum acquisition time, 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).


;[2] V
;combining [1] and [2]
;[1] V
PICmicro
CHOLD
CHOLD
®
+
Temperature Coefficient
charge response to V
charged to within 1/2 lsb
Mid-Range
PIC16F785
Reference
DS41249A-page 83
APPLIED
ACQ
Manual
, see