FIGURE 2. TYPICAL RELAY APPLICATION

R1 = See NOTE 2

R2 = 36k

Ω

R3 = 2.7M

Ω

R4 = 36k

Ω

R5 = 2.7M

Ω

C1 = 100µF

C2 = 33µF

C3 = 0.01µF

C4 = 33µF

C5 = 0.01µF

C6 = 0.01µF (Typical)

C7 = 0.22µF (CP Mode; Typical)

C7 = 0.68µF (DPMode; Typical)

C8 = 0.22µF (Typical)

C9 = 0.1µF

D1 = 1N4001

RELAY = No typical P/N

PIR = HEIMANN LHi 958, 968 (Typical)

All Resistors 1/4W.

All Capacitors 10V.

NOTE 2:

R1 is selected to provide sufficient

current to drive the LS6511 and PIR Sensor. Any

surplus current is available to drive additional

loads applied to the 5V Shunt Regulator output or

is absorbed by the 5V Shunt Regulator. Refer to

specifications for current limits.

NOTE 3: In SP Mode, R7 and C7 are not used

and Pin 5 is tied to Vss.

R6 = 2.2M

Ω (Typical)

R7 = 2.2M

Ω (Typical)

R8 = 2.2M

Ω (Typical)

R9 = 3k

Ω

R10 = 2.2k

Ω (Typical)

NOTE 1: The relay coil is normally energized and the LED is off.

When an alarm occurs, the relay coil becomes de-energized and

the LED is turned on.

AMP 1

OUT

AMP 1

(-)IN

AMP 2

(-)IN

AMP 1

(+)IN

AMP 2

OUT

5V REG

OUT

CP MODE or

DP MODE RC

LED/REL

OUT

C4

R4

C5

R5

1

2

3

4

5

6

7

9

10

11

12

13

14

C2

R2

R9

C9

R1

C1

PIR

SENSOR

R3

C3

LS6511

C6

R6

+

-

+

-

+

-

8

C7

R7

C8

R8

D1

LED/REL

OUT

MODE

DIG FILTER

RC

DUR TIM

RC

RELAY

COIL

RAW

DC

INPUT

R10

LED

S = 3-Position SPDT (On-Off-On)

S

See Note 3

Using the typical application circuit as shown in Figure 2,

the Outputs on Pins 8 and 9 occur on power-up because of

the large settling time in the amplifier stages. In applications

where this is not desireable, the digital filter oscillator must

be disabled on power-up long enough to enable the PIR

amplifiers to stabilize. Replacing the R6-C6 circuit shown in

Figure 2 with the circuit shown in Figure 3 will disable the

digital filter oscillator until the voltage across the 220µF

capacitor reaches a value high enough for the oscillator to

begin oscillating. Component values that can be changed to

speed up stabilization include C2, C3, C4 and C5. C3 and

C5 become 0.001µF and C2 and C4 become 10µF.

FIGURE 3. INHIBITING OUTPUTS UPON POWER TURN-ON

LS6511 - 4

2.2M

.01µF

220µF

100k

R6

C6

+

6511-102402-3

NOISE CONSIDERATIONS

Layout of any circuit using a high-gain PIR amplifier is critical.

The PIR amplifier components should be located close to the

amplifier pins on the chip in order to minimize noise pickup.The

oscillator and relay drive components should be located away

from the amplifier components.

Other steps that can help reduce noise is adding a ground

shield backplane to the PCB and enhancing the filtering of

VDD; i.e., adding a 0.1uF high frequency capacitor across C1

and increasing C1 to 220 µF.