Datasheet KC778B Datasheet (COMedia Ltd)

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KC778B Rev C, 1996

KC778B

Master PIR Control Chip (MPCC)

Specification

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General :

The MPCC has been designed for easy implementation
of AC control functions that use a Passive Infra-Red
(PIR) motion detector. Due to its high sensitivity and
reliability, it is also widely used in security product.

• Minimum external component

• High senstivity

• High RFI immunity

• Daylight adjustment

• Off delay timer

Features:

A) Circuit design maximizes performance while minimizing external component count and board layout space.
B) Low cost solution for PIR motion control switching applications.
C) High sensitivity PIR input with special noise cancellation circuitry.
D) Choice of two PIR gain settings: 62 db and 68 db.
E) Adjustable PIR sensitivity.
F) Internal switched capacitor bandpass filter reduces external component count and improves reliability by

minimizing sensitivity to external component values.
G) RFI noise immunity exceeds 30 V/m from 1 MHz to 1000 MHz.
H) High immunity to line frequency noise.
I) Daylight detector circuitry is designed to use either silicon photo diode or CdS detector.
J) Adjustable daylight detector sensitivity.
K) Adjustable OFF timer accuracy is determined by external components.
L) Output can directly drive TRIACs, opto-couplers and small relays (no buffering required).
M) Four main operating modes can be used in any combination:

1)Auto-ON: Load turns on when motion is detected (adjustable sensitivity).
Adjustable daylight detector disables Auto-ON during daytime.
Auto-ON mode can be disabled.
Daylight detector can be disabled.

2)Auto-OFF: Adjustable OFF timer activates whenever motion stops.
Load turns off if there is no motion during the time delay.
If Auto-ON mode is disabled, the load will turn on if there is motion within 6 seconds
after turn-off. (If the load goes off because you stopped moving (reading a book for
example), you have 6 seconds to wave your arm to turn the load back on.)
Auto-OFF mode can be disabled.

3)Manual-ON: Load turns on manually, with a momentary contact switch.

4)Manual-OFF: Load turns off manually, with a momentary contact switch.
Load will remain off for 25 seconds, even if there is motion during this time (to give you
time to leave the room).

N) If the ON/AUTO/OFF input is held either high or low, the load will be held ON or OFF respectively,

overriding all other modes, until the input returns to the AUTO position.

O) If the Toggle input is held low, the load will change from on to off or from off to on, and will be held in

that state, overriding all other modes, until the input returns high.
P) When power is restored after an outage, the load will be OFF and motion will be ignored for 25 seconds.
Q) Operating chip voltage is 4 - 15V.
R) Operating chip current is typically 300 µA.
S) Chip is ESD protected to more than 1000 V (human body model).
T) Operates with 50-60 Hz AC line frequency.

20 pin DIP

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2 KC778B

Pin Assignment :

Pin Descriptions

1. Vcc : This is the regulated supply voltage to the chip (nominally 5 V).

2. Sensitivity Adjust: This pin is used to adjust the sensitivity threshold of the motion comparators. When the

voltage on this pin equals the pyro drain reference voltage on pin 7 the PIR sensitivity will be minimum

(±500 mV). When the voltage on this pin is Gnd the PIR sensitivity will be maximum (±125 mV).

Intermediate voltages will provide intermediate sensitivities.

3. Offset Filter: This pin connects to an external capacitor of 10 µF and holds the average value of the

switched capacitor bandpass filter output. Motion is detected when the difference between this average and

the actual filter output is greater than the sensitivity setting. The output of the switched capacitor bandpass

filter can be seen directly on this pin if the external capacitor is disconnected, however, motion will not be

detected under these conditions.

4. Anti-Alias: This pin connects to an external capacitor of 0.1 µF providing low pass filtering of the PIR

input signal, blocking input signals at and above the switching frequency of the switched capacitor

bandpass filter.

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

10 11

20 pin DIP or SOIC

Pin Name Description

1 Vcc Supply Voltage (5 V)
2 Sensitivity Adjust PIR Motion Sensitivity Input
3 Offset Filter PIR Motion Offset Filter
4 Anti-Alias PIR Anti-Alias Filter
5 DC CAP PIR Gain Stabilization Filter
6 VReg Voltage Regulator Output
7 Pyro (D) Pyro Drain Reference
8 Pyro (S) Pyro Source Input Signal

9 Gnd (A) Analog Circuitry Ground
10 Gnd (D) Digital Circuitry Ground
11 Daylight Adjust Daylight Adjustment and CdS Input
12 Daylight Sense Silicon Photo Diode Input
13 Gain Select PIR Gain Select Tri-State Input
14 ON/AUTO/OFF Mode Select Tri-State Input
15 Toggle Mode Select Toggle Input
16 OUT Lights ON/OFF Output
17 LED PIR Motion Indicator Output
18 C OFF Timer Oscillator Input
19 R OFF Timer Oscillator Output
20 FRef Frequency Reference Oscillator

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MPCC 3

5. DC CAP: This pin connects to an external capacitor of 10 µF and holds the average pyro source voltage.

The difference between this average and the actual pyro source voltage is amplified and coupled to the
switched capacitor bandpass filter. The 10 µF capacitor must be a low leakage capacitor, such as a
Tantalum capacitor.

6. VReg: This pin outputs a voltage that can be used directly drive an external NPN/PNP volatage regulator,

or the gate of an external depletion mode JFET voltage regulator pass element. This pin need not be
connected if an external voltage regulator, such as a three pin regulator, is used to generate Vcc for the
chip.

7. Pyro (D): The pyro drain reference voltage is output on this pin. This voltage is power supply independent

and is connected internally to special noise cancellation circuitry to improve the performance and reliability
of the PIR interface. Externally, this pin is connected to the pyro drain and to a 0.1 µF capacitor. This
voltage can also be divided down by an external pot to supply the Sensitivity Adjust voltage to pin 2.

8. Pyro (S): This is the pyro source input pin that receives the PIR input signal. It is connected externally to

the pyro source, a 200 pF capacitor and a 47 K

Ω

resistor to Gnd. This is a sensitive node and the length of

the external interconnect to this pin should be made as short as possible. There should be a ground plane
on the PC board under the PIR sensor.

9. Gnd (A): This pin is the electrical ground for the internal analog circuitry of the chip.

10. Gnd (D) : This pin is the electrical ground for the internal digital circuitry of the chip.

11. Daylight Adjust: This pin is the output of the Daylight Sense amplifier and the input to the daylight

comparator. When using a silicon photo diode daylight sensor, this pin is connected to Daylight Sense (pin

12) by a resistor or pot. The amount of resistance determines the gain of the Daylight Sense amplifier and
hence the sensitivity of the daylight detector. When using a CdS daylight sensor, a pot is connected
between this pin and Vcc, while the CdS sensor is connected across one side of the pot (two fixed resistors
can be used instead of the pot). Daylight Sense (pin 12) must be connected to Vcc when using a CdS
sensor. To disable the daylight detector, Daylight Adjust (pin 11) must be unconnected and Daylight Sense
(pin 12) must be connected to Vcc. To disable Auto-ON mode, Daylight Adjust (pin 11) and Daylight
Sense (pin 12) must both be connected to Vcc (the daylight detector is not used when Auto-ON mode is
disabled).

12. Daylight Sense: This pin is the input to the Daylight Sense amplifier. When using a silicon photo diode

daylight sensor, this pin is connected to the cathode of the silicon photo diode and to a feedback resistor (or
pot) from Daylight Adjust (pin 11). In all other cases, this pin is connected to Vcc.

13. Gain Select: The Gain Select pin is a tri-state input used to select the gain of the PIR circuitry. When this

pin is connected to Gnd, the PIR gain is set to 62 db. When this pin is unconnected or connected to Vcc,
the PIR gain is set to 68 db. Normally this pin is unconnected except when less gain is required by a
particular PIR sensor.

14. ON/AUTO/OFF: This pin is a tri-state input used to determine the operation of the chip. Normally this

pin is unconnected, allowing the chip to operate in its configured operating mode. If this pin is connected
to Gnd, the load will turn off unconditionally and will remain off as long as this pin is connected to Gnd. If
this pin is connected to Vcc, the load will turn on unconditionally and will remain on as long as this pin is
connected to Vcc.

15. Toggle: This pin is a toggle input used to determine the operation of the chip. Normally this pin is

unconnected, allowing the chip to operate in its configured operating mode. If this pin is connected to
Gnd, the load will change from on to off or from off to on and will remain in the new state unconditionally
as long as this pin is connected to Gnd. If the ON/AUTO/OFF (pin 14) and Toggle (pin 15) switches are
pressed such that one is trying to turn the load on unconditionally and the other is trying to turn the load off
unconditionally, the load will be turned off (off overrides on).

16. OUT : The output from this pin is used to turn the external load on or off through a TRIAC, relay or opto-

coupler. The impedance of this pin is less than 35

Ω

, enabling it to directly drive a small (100 Ω DC coil
resistance) pulse relay through a 150 µF series capacitor. For proper operation, the load should come on
when this pin goes high, the load should go off when this pin goes low.

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4 KC778B

17. LED: The output from the motion comparator drives this pin through an internal 500

Ω

current limiting
resistor, enabling it to directly drive an LED motion indicator. Whenever motion is detected this pin will
go high and the LED will light. When there is no motion this pin will be low.

18. C: This pin is the input to the OFF timer oscillator. It is connected externally to a pot (or resistor) from R

(pin 19) and to a capacitor. The OFF timer delay, in seconds, will be 5678 x (40,000 + pot resistance in
Ohms) x (capacitance in Farads). To disable Auto-OFF mode, this pin can be connected to Gnd or Vcc.
For minimum time delay, C(pin 18) and R(pin 19) can be shorted together with no external resistor or
capacitor. In this configuration, the output at OUT(pin 16) should be the same as the output at LED(pin

17).

19. R : The output of the OFF timer oscillator drives this pin through an internal 40 K

Ω

series resistor. This
pin is connected externally to C (pin 18) through a pot (or resistor). This pin can be connected directly to
C (pin 18) for the minimum OFF timer delay (maximum oscillator frequency).

20. FRef : This is the 160 Hz reference oscillator input. It is connected externally through a 330K

Ω

resistor to

Vcc and a 0.022µF capacitor to Gnd. Other values of resistance and capacitance can be chosen, provided
this input oscillates at 160Hz. This frequency is used to drive the internal switched capacitor bandpass filter
and the timing delays.

Electrical Specifications

Below are the specifications at room temperature (25 °C).

Parameter Min. Typ. Max. Unit

Vcc 4 5 15 V

Icc 300 µA

Input Voltage on any Pins Gnd - 0.5 Vcc + 0.5 V

PIR Power Supply Rejection Ratio 74 dB

PIR Input Gain 62 68 dB

Overall gain variation 5 %

Overall threshold variation 7 %

Daylight Adjust (pin 11) Pull-down Current 5

µA

Gain Select (pin 13) Pull-up Current 5 µA

ON/AUTO/OFF (pin 14) Pull-up Current 10 µA

ON/AUTO/OFF (pin 14) Pull-Down Current

10 µA

Toggle (pin 15) Pull-up Current 5 µA

Pyro (D) (pin 7) Reference Voltage 2.3 2.5 2.7 V

OUT (pin 16) Output Impedance 35

Ω

LED (pin 17) Output Impedance 375 500 625

Ω

R (pin 19) Output Impedance 30 40 50

K

Ω

Operating Temperature -25 +100 °C

Storage Temperature -55 +125 °C

Application Notes:

1. Normally, Gain Select (pin 13) is unconnected, providing a PIR gain of 68 db. For reduced sensitivity, Gain
Select is connected to Gnd, providing a gain of 62 db.

2. Auto-ON mode can be disabled by connecting both Daylight Sense (pin 12) and Daylight Adjust (pin 11) to
Vcc.

3. Auto-OFF mode can be disabled by connecting C (pin 18) to Gnd or Vcc.

4. Daylight detector can be disabled by connecting Daylight Sense (pin 12) to Vcc.

5. With a 5 M

Ω

Daylight adjust pot, the daylight sensitivity can be adjusted from complete darkness (always
on) to complete daylight (always off). Additional fixed resistors and possibly a smaller pot can be used to
restrict the range for specific applications.

6. The OFF timer range can be set by selecting a pot and capacitor and possibly additional fixed resistors that
will produce the minimum and maximum time delays at the extremes of the pot.

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MPCC 5

7. OFF timer delay = 5678 x (R+40,000) x C seconds, R is in Ohms, C is in Farads.

8. The Sensitivity Adjust pot is used to select a voltage between the pyro drain reference voltage (minimum
sensitivity) and Gnd (maximum sensitivity). The value of the pot is not critical and any value between 100
K

Ω

and 5 MΩ can be used.

9. The output of the switched capacitor bandpass filter can be seen on pin 3 (Offset Filter) when the external
capacitor(10µF) is disconnected. The filter response can be measured in this way. (Disconnecting the
external capacitor prevents motion from being detected.)

10. Pin 8 (Pyro (S)) is a sensitive node and the external interconnect to this pin should be made as short as
possible. This node should also be closely surrounded by a ground plane.

Block Diagram

VCC

Sensitivity
Adjust

Offset Filter

Pyro (D)
Pyro (S)
Gain Select
Anti-Alias
DC Cap

FRef
R
C

On/Auto/off
Toggle

Daylight
Sense

Daylight
Adjust

GND

PIR Front End

Amplifiers and

Noise Cancellation

Circuitry

Switched

Capacitor

Bandpass Filter

Oscillation and

Synchronization

Circuitry

Threshold

Comparators

and Timing

Circuitry

Daylight Detector

Amplifier and

Comparator

Voltage Regulator

LED

OUT

Vreg

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6 KC778B

Application Circuit

1. Typical Hook-up

Below is a typical hook up for connecting KC778B to a PIR sensor, a TRIAC light switch and a silicon
photodiode daylight detector. VReg is used for voltage regulation. 2 slide switches are used. One for select
ON/AUTO/OFF and the other one used for enable, disable the daylight sensor and disable auto-on function.
A simple AC regulation circuit is used in this system such that only a small gate current TRIAC can be
used.

(L)

LIGHT

100

1W

400V

.47uF

470K

X24004

1N

470

8550

10uF 470uF

C9014

12V

.1uF

.01uF
400V

TRIAC

AC

200V

(N)

1K

330K

.022uF

20OSC

1 VCC

KC778B

500K

MAX

MIN

10uF

23PIR

SENS
OFFSET

FILTER

1819C

R

OFF TIMER

R

C

AUTO

TOGGLE ON-OFF

15

16

17

TOGGLE

OUT

LED4

5

6

LP
FILTER

DC
CAP

VREG

10uF
TAN

.1uF

PIR

.1uF

47K

7

8

9

PYRO

PYRO

GND

(D)

(S)

(A)

12

13

14

DAY

SENS

GAIN

ON/OFF

NC

ON

OFF
DISABLE AUTO-ON
DISABLE DAY SENS

20K

5M PHOTO

DIODE

DAY SENSOR11DAY

ADJ

SW 2P3T

10 GND

(D)

200pF

Note : Off Time Delay = 5678 x (R+40,000) x C Second

R in Ohm, C in Farad

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MPCC 7

2. Hook-up with with relay

The following is similar to the typical hook-up. Due to the higher current require by relay, the bridge
regulation method is used in AC circuit. This application is suitable to a high current loading such as
heater, flood light, motor and etc.

(L)

100

1W

400VX4

1uF

200

1N4004

470

8550

10uF 470uF

C9014

12V

470K .01uF

400V

(N)

200V AC

100uF

330K

500K

MIN

MAX

12VCC

PIR
SENS

KC778B

1920R

R

OFF TIMER

OSC

C

.022uF

LOAD

RELAY(12VDC)

4001

8050

1K

TOGGLE ON-OFF

16

17

18

OUT

LED

COFFSET

FILTER
LP

FILTER
DC

CAP

3

4

510uF

TAN

.1uF

10uF

PIR

.1uF

6

7

8

PYRO

PYRO

(D)

(S)

VREG

13 NC

14

15

GAIN

ON/OFF

TOGGLE

ON
OFF

AUTO

DISABLE AUTO-ON

20K

5M PHOTO

DIODE

DAY SENSOR

DISABLE DAY SENSE

11

12

DAY
ADJ

DAY

SENS

GND

GND

(A)

(D)

9

10

200pF

47K

SW 2P3T

Note : Off Time Delay = 5678 x (R+40,000) x C Second

R in Ohm, C in Farad

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8 KC778B

3. Hook-up with minimun regulator

Below is an example of 110V application. Only one stages of regulator is used in the system by use of
zener diode

LIGHT

(L)

100

1W

400VX2

470K

1uF

4004

1N

220

1N4148

10uF

5.6V

470uF

.1uF .01uF

400V

TRIAC

110v

AC

(N)

.022uF

330KKC778B

500K

MAX

MIN

1

2

310uF

VCC

PIR
SENS

OFFSET
FILTER

18

19

20

C

R

R

OFF TIMER

OSC

C

1K

TOGGLE ON-OFF

15

16

17

TOGGLE

OUT

LEDLP

FILTER
DC

CAP
VREG

4

5

6

10uF
TAN

.1uF

.1uF

PIR

7

8

947K

PYRO

PYRO

GND

(D)

(S)

12

13 NC

14

DAY

GAIN

ON/OFF

ON
OFF

AUTO

DISABLE AUTO-ON

20K

5M PHOTO

DIODE

DAY SENSOR

DISABLE DAY SENS

11DAY

ADJ

SENS

GND

(A)

(D)

10

200pF

SW 2P3T

Note : Off Time Delay = 5678 x (R+40,000) x C Second
R in Ohm, C in Farad

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MPCC 9

4. Hook-up with 12VDC system

Below is an example of Auto camp light which uses an auto battery (12VDC). Internal voltage regulator is
used, it needs 12V to start up but can work down to 7V.

C1

470uF

Q1
8550

Q2
9013

C2

220uF

KC778B

R1
330K

C9

223

LP1
LAMP

1920R

OSC

R2

120K

12VCC

PIR
SENS

C3

10uF

D1
1N4001

BT1
12V

C4

104

C5

10uF

34OFFSET

FILTER
LP

FILTER

17

18

LED

C

C8
104

D2
1N4148

K1
RELAY

Q3
8050

R5 1K

R3
20K

S1

MANUAL OVERRIDE

15

16

TOGGLE

OUT56DC

CAP
VREF

TAN

C6

104

PIR

78PYRO

PYRO

(D)

(S)

13

14

GAIN

ON/OFF

R6

100K

CdS

R7
510k

11

12

DAY
ADJ

DAY

SENS

910GND

GND

(A)

(D)

C7

200P

R4
47K

5. Hook-up with Door Chime and Alarm circuit

A 2P3T slide switch is used in the system.When it is positioned at Chime, the LED output of KC778B will
trigger the door bell COB at anytime. If the switch is positioned at OFF, power will be cut off. When switch
to Alarm position, after 25sec delay, the KC778B start working. It outputs a high signal when motion is
detected. This signal will charge up the cap such that the siren COB will be triggered after the charge up
delay time. It forms a very simple alarm product.

SW1

2P3T

CHIME

R1
330K

R5

100
C4
100uF

C5
470uF

D2

IN4148

OFF
ALARM

BT1
6V

C1

223

1
2
3
4
5
6
7
8
9
10 11

12

13

14

15

16

17

18

19

20

U1

KC778B

R2

220K

C2

103

PIEZO

T1

CHOKE

COB

DOOR BELL

TRG

R3

56

D1

1N4148

R4

68K

SW2

2P3T

Q1
8050

SIREN

COB

TRG

C3

100uF