PIC16F785-ESLASHP datasheet(79/206 Pages) MICROCHIP

79 / 206 page

DS41249E-page 77

PIC16F785/HV785

11.3

Effects of a Reset

A device Reset forces all registers to their Reset state.

This disables both op amps.

11.4

OPA Module Performance

Common AC and DC performance specifications for

the OPA module:

• Common Mode Voltage Range

• Leakage Current

• Input Offset Voltage

• Open Loop Gain

• Gain Bandwidth Product (GBWP)

Common mode voltage range is the specified voltage

range for the OPA+ and OPA- inputs, for which the OPA

module will perform to within its specifications. The

OPA module is designed to operate with input voltages

between 0 and VDD-1.4V. Behavior for common mode

voltages greater than VDD-1.4V, or below 0V, are

beyond the normal operating range.

Leakage current is a measure of the small source or

sink currents on the OPA+ and OPA- inputs. To mini-

mize the effect of leakage currents, the effective imped-

ances connected to the OPA+ and OPA- inputs should

be kept as small as possible and equal.

Input offset voltage is a measure of the voltage differ-

ence between the OPA+ and OPA- inputs in a closed

loop circuit with the OPA in its linear region. The offset

voltage will appear as a DC offset in the output equal to

the input offset voltage, multiplied by the gain of the

circuit. The input offset voltage is also affected by the

common mode voltage.

Open loop gain is the ratio of the output voltage to the

differential input voltage, (OPA+) - (OPA-). The gain is

greatest at DC and falls off with frequency.

Gain Bandwidth Product or GBWP is the frequency

at which the open loop gain falls off to 0 dB.

11.5

Effects of Sleep

When enabled, the op amps continue to operate and

consume current while the processor is in Sleep mode.

TABLE 11-1:

REGISTERS ASSOCIATED WITH THE OPA MODULE

Name

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Value on

POR, BOR

Value on all

other Resets

ANSEL0

ANS7

ANS6

ANS5

ANS4

ANS3

ANS2

ANS1

ANS0

1111 1111

ANSEL1

—

ANS11

ANS10

ANS9

ANS8

---- 1111

OPA1CON

OPAON

—

0--- ----

OPA2CON

OPAON

—

0--- ----

TRISB

TRISB7

TRISB6

TRISB5

TRISB4

—

1111 ----

TRISC

TRISC7

TRISC6

TRISC5

TRISC4

TRISC3

TRISC2

TRISC1

TRISC0

1111 1111

Legend:

= unknown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used for the OPA module.

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