PIC16LC71-04I/SO Microchip Technology, PIC16LC71-04I/SO Datasheet - Page 43

• Manufacturer Part Number: PIC16LC71-04I/SO
• Description: IC MCU OTP 1KX14 A/D 18SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16LC71-04I/SO

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: POR, WDT
• Number Of I /o: 13
• Program Memory Size: 1.75KB (1K x 14)
• Program Memory Type: OTP
• Ram Size: 36 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 4x8b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 18-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Connectivity: -

7.4.1
Not all applications require a result with 8-bits of reso-
lution, but may instead require a faster conversion time.
The A/D module allows users to make the trade-off of
conversion speed to resolution. Regardless of the res-
olution required, the acquisition time is the same. To
speed up the conversion, the clock source of the A/D
module may be switched so that the T
the minimum specified time (see the applicable electri-
cal specification). Once the T
mum specified time, all the following A/D result bits are
not valid (see A/D Conversion Timing in the Electrical
Specifications section.) The clock sources may only be
switched between the three oscillator versions (cannot
be switched from/to RC). The equation to determine
the time before the oscillator can be switched is as
follows:
EXAMPLE 7-3:
Note 1: The PIC16C71 has a minimum T
T
T
2T
1997 Microchip Technology Inc.
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OSC
Conversion time = 2T
Where: N = number of bits of resolution required.
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+ N • T
FASTER CONVERSION - LOWER
RESOLUTION TRADE-OFF
All other PIC16C71X devices have a minimum T
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+ (8 - N)(2T
4-BIT vs. 8-BIT CONVERSION TIMES
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+ N • T
OSC
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)
time violates the mini-
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+ (8 - N)(2T
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time violates
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time of 2.0 s.
OSC
)
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time of 1.6 s.
Since the T
user must use some method (a timer, software loop,
etc.) to determine when the A/D oscillator may be
changed. Example 7-3 shows a comparison of time
required for a conversion with 4-bits of resolution, ver-
sus the 8-bit resolution conversion. The example is for
devices operating at 20 MHz and 16 MHz (The A/D
clock is programmed for 32T
immediately after 6T
for 2T
The 2T
last 4-bits will not be converted to correct values.
Freq. (MHz)
OSC
OSC
20
16
20
16
20
16
.
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violates the minimum T
(1)
is based from the device oscillator, the
AD
62.5 ns
12.5 s
1.6 s
2.0 s
10 s
50 ns
, the A/D clock is programmed
4-bit
PIC16C71X
OSC
Resolution
), and assumes that
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DS30272A-page 43
time since the
62.5 ns
1.6 s
2.0 s
50 ns
16 s
20 s
8-bit