Datasheet

PIC16C77X
DS30275B-page 124 Advance Information  1999-2013 Microchip Technology Inc.
FIGURE 11-7: CALCULATING THE MINIMUM REQUIRED SAMPLE TIME
TACQ = Amplifier Settling Time
+ Holding Capacitor Charging Time
+Temperature Coefficient †
T
ACQ =5 s
+ T
C
+ [(Temp - 25C)(0.05s/C)] †
T
C = + Holding Capacitor Charging Time
T
C =(CHOLD) (RIC + RSS + RS) In (1/16384)
T
C = -25 pF (1 k +10 k + 2.5 k) In (1/16384)
T
C = -25 pF (13.5 k) In (1/16384)
T
C = -0.338 (-9.704)s
T
C =3.3s
T
ACQ =5s
+ 3.3 s
+ [(50C - 25C)(0.05s / C)]
T
ACQ = 8.3 s + 1.25s
T
ACQ = 9.55 s
† The temperature coefficient is only required for
temperatures > 25C.
FIGURE 11-8: ANALOG INPUT MODEL
CPIN
VA
Rs
Port Pin
5 pF
V
DD
VT = 0.6V
V
T = 0.6V
I
LEAKAGE
RIC  1k
Sampling
Switch
SS
R
SS
CHOLD = 25 pF
V
SS
6V
Sampling Switch
5V
4V
3V
2V
567891011
( k )
VDD
 100 nA
Legend CPIN
VT
ILEAKAGE
RIC
SS
C
HOLD
= input capacitance
= threshold voltage
= leakage current at the pin due to
= interconnect resistance
= sampling switch
= sample/hold capacitance (from DAC)
various junctions
774.book Page 124 Tuesday, January 29, 2013 12:02 PM