TC1043CEQR datasheet(7/20 Pages) MICROCHIP

Il numero della parte	TC1043CEQR

Spiegazioni elettronici	Linear Building Block . Low Power Voltage Reference with Dual Op Amp, Dual Comparator, and Shutdown Mode

Download	20 Pages

Scroll/Zoom	100%

Produttore elettronici	MICROCHIP [Microchip Technology]

Homepage	http://www.microchip.com

Logo

7 / 20 page

DS21347B-page 7

TC1043

EQUATION 4-1:

4.

Choose the rising threshold voltage for VSRC

(VTHR).

5.

Calculate RB as follows:

EQUATION 4-2:

6.

Verify the threshold voltages with these formu-

las:

VSRC rising:

EQUATION 4-3:

VSRC falling:

EQUATION 4-4:

4.5

32.768kHz ‘Time Of Day Clock’

Crystal Controlled Oscillator

A very stable oscillator driver can be designed by using

a crystal resonator as the feedback element. Figure 4-

5 shows a typical application circuit using this tech-

nique to develop a clock driver for a Time-Of-Day

(TOD) clock chip. The value of RA and RB determines

the DC voltage level at which the comparator trips; in

this case one-half of VDD. The RC time constant of RC

and CA should be set several times greater than the

crystal oscillator’s period, which will ensure a 50% duty

cycle by maintaining a DC voltage at the inverting com-

parator input equal to the absolute average of the out-

put signal.

4.6

Non-Retriggerable One Shot Multi-

vibrator

Using two comparators, a non-retriggerable, one shot

multi-vibrator can be designed using the circuit config-

uration of Figure 4-6. A key feature of this design is that

the pulse width is independent of the magnitude of the

supply voltage because the charging voltage and the

intercept voltage are a fixed percentage of VDD. In addi-

tion, this one shot is capable of pulse width with as

much as a 99% duty cycle and exhibits input lockout to

ensure that the circuit will not re-trigger before the out-

put pulse has completely timed out. The trigger level is

the voltage required at the input to raise the voltage at

node A higher than the voltage at node B, and is set by

the resistive divider R4 and R10 and the impedance

network composed of R1, R2 and R3. When the one

shot has been triggered, the output of CMPTR2 is high,

causing the reference voltage at the non-inverting input

of CMPTR1 to go to V

DD. This prevents any additional

input pulses from disturbing the circuit until the output

pulse has timed out.

Thevalue of thetimingcapacitor C1must besmall

enough to allow CMPTR1 to discharge C1 to a diode

voltage before the feedback signal from CMPTR2

(through R10) switches CMPTR1 to its high state and

allows C1 to start an exponential charge through R5.

Proper circuit action depends upon rapidly discharging

C1 through the voltage set by R6, R9 and D2 to a final

voltage of a small diode drop. Two propagation delays

after the voltage on C1 drops below the level on the

non-inverting input of CMPTR2, the output of CMPTR1

switches to the positive rail and begins to charge C1

through R5. The time delay which sets the output pulse

width results from C1 charging to the reference voltage

set by R6, R9 and D2, plus four comparator propaga-

tion delays. When the voltage across C1 charges

beyond the reference, the output pulse returns to

ground and the input is again ready to accept a trigger

signal.

4.7

Oscillators and Pulse Width

Modulators

Microchip’s linear building block comparators adapt

well to oscillator applications for low frequencies (less

than 100kHz). Figure 4-7 shows a symmetrical square

wave generator using a minimum number of compo-

nents. The output is set by the RC time constant of R4

and C1, and the total hysteresis of the loop is set by R1,

R2 and R3. The maximum frequency of the oscillator is

limited only by the large signal propagation delay of the

comparator in addition to any capacitive loading at the

output which degrades the slew rate.

To analyze this circuit, assume that the output is initially

high. For this to occur, the voltage at the inverting input

must be less than the voltage at the non-inverting input.

Therefore, capacitor C1 is discharged. The voltage at

the non-inverting input (VH)is:

EQUATION 4-5:

where, if R1 = R2 = R3, then:

EQUATION 4-6:

R

A

R

C

V

HY

V

DD

-----------





=

R

B

1

V

THR

V

R

A

×

---------------------







 1

R

A

-------

–

1

R

C

-------

–

-----------------------------------------------------------

=

V

TH R

V

R

() R

A

()

1

R

A

-------





1

R

B

-------





1

R

C

-------





++

=

V

THF

V

THR

R

A

V

DD

×

()

R

C

------------------------------

–

=

V

H

R2 V

DD

()

R2

R1 R3

||

()

+

[]

---------------------------------------------

=

V

H

2V

DD

()

3

-------------------

=

Codice articolo simile - TC1043CEQR

Produttore elettronici	Il numero della parte	Scheda tecnica	Spiegazioni elettronici
Microchip Technology	TC1040	444Kb / 14P	Linear Building Block . Dual Low Power Comparator and Voltage Reference with Shutdown 2002
	TC1040CEUA	444Kb / 14P	Linear Building Block . Dual Low Power Comparator and Voltage Reference with Shutdown 2002
	TC1041	443Kb / 14P	Linear Building Block . Dual Low Power Comparator and Voltage Reference with Programmable Hysteresis 2002
	TC1041CEOA	443Kb / 14P	Linear Building Block . Dual Low Power Comparator and Voltage Reference with Programmable Hysteresis 2002
	TC1041CEUA	443Kb / 14P	Linear Building Block . Dual Low Power Comparator and Voltage Reference with Programmable Hysteresis 2002

More results

Descrizione simile - TC1043CEQR

Produttore elettronici	Il numero della parte	Scheda tecnica	Spiegazioni elettronici
TelCom Semiconductor, I...	TC43	75Kb / 6P	LINEAR BUILDING BLOCK - VOLTAGE REFERENCE, DUAL OP AMP, DUAL COMPARATOR WITH SHUTDOWN MODE
Microchip Technology	TC1040	444Kb / 14P	Linear Building Block . Dual Low Power Comparator and Voltage Reference with Shutdown 2002
TelCom Semiconductor, I...	TC1026	26Kb / 1P	LINEAR BUILDING BLOCK - LOW POWER COMPARATOR WITH OP AMP AND VOLTAGE REFERENCE
Microchip Technology	TC1026	517Kb / 18P	Linear Building Block - Low Power Comparator with Op Amp and Voltage Reference 2002
TelCom Semiconductor, I...	TC1028	26Kb / 1P	LINEAR BUILDING BLOCK - QUAD LOW POWER COMPARATOR AND VOLTAGE REFERENCE WITH SHUTDOWN
Microchip Technology	TC1031	257Kb / 14P	Linear Building Block - Low Power Voltage Reference with Programmable Hysteresis Comparator and Shutdown 2005
Microchip Technology	TC1031	430Kb / 12P	Linear Building Block . Low Power Voltage Reference with Programmable Hysteresis Comparator and Shutdown 2002
TelCom Semiconductor, I...	TC1029	25Kb / 1P	LINEAR BUILDING BLOCK - DUAL LOW POWER OP AMP
Microchip Technology	TC1029	486Kb / 14P	Linear Building Block - Dual Low Power Op Amp 2002
Microchip Technology	TC1041	443Kb / 14P	Linear Building Block . Dual Low Power Comparator and Voltage Reference with Programmable Hysteresis 2002

More results

TC1043CEQR Scheda tecnica(PDF) 7 Page - Microchip Technology

TC1043CEQR Scheda tecnica(HTML) 7 Page - Microchip Technology

Codice articolo simile - TC1043CEQR

Descrizione simile - TC1043CEQR

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Scheda tecnica Scarica

Link URL