COMedia Ltd KC778B Datasheet

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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.