PIC16F636-I/P Microchip Technology Inc., PIC16F636-I/P Datasheet - Page 94

• Manufacturer Part Number: PIC16F636-I/P
• Description: 14 PIN, 3.5 KB FLASH, 128 RAM, 12 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F636-I/P

• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 12
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 14-pin PDIP
• Programmable Memory: 3.5K Bytes
• Ram Size: 128 Bytes
• Speed: 20 MHz
• Timers: 1-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC12F635/PIC16F636/639
11.26 Factory Calibration
Microchip calibrates the AFE to reduce the device-to-
device variation in standby current, internal timing and
sensitivity, as well as channel-to-channel sensitivity
variation.
11.27 De-Q’ing of Antenna Circuit
When the transponder is close to the base station, the
transponder coil may develop coil voltage higher than
V
detects the strong near field signal through the AGC
control, and de-Q’ing the antenna circuit to reduce the
input signal amplitude.
FIGURE 11-8:
DS41232B-page 92
DE
V
_
Legend:
BAT
Q
. This condition is called “near field”. The AFE
D
D
C
BLOCK
BLOCK
D
C
R
POOL
D
R
FLAT
COM
COM
LIM
LIM
LF FIELD POWERING AND BATTERY BACK-UP EXAMPLE
= LCCOM charging capacitor.
= Pool capacitor (or battery back-up capacitor), charges in field and powers device.
= Battery protection from reverse charge.
= Field rectifier diodes.
= Voltage limiting diode, may be required to limit V
= Ccom discharge path.
= Current limiting resistor, required for air coil in strong fields.
Schottky for low forward bias drop.
D
LIM
V
DD
C
POOL
D
D
Preliminary
FLAT
FLAT
1
2
Air Coil
L
X
11.28 Battery Back-up and Batteryless
The device supports both battery back-up and
batteryless operation by the addition of external
components, allowing the device to be partially or
completely powered from the field.
Figure 11-8 shows an example of the external circuit for
the battery back-up.
Note:
R
L
C
Y
COM
X
R
LIM
Operation
DD
Voltage on L
voltage must not exceed the maximum LC
input voltage.
C
C
voltage when in strong fields.
COM
Y
L
Z
© 2005 Microchip Technology Inc.
CCOM
C
Z
LCCOM
combined with coil input
LCX
LCY
LCZ