BL59A10/BL59S10
5.Pin description
Pin
Symbol
No.
1,2
C1, C2
Input/output
Functions
External capacitor
connection
I
Detecting input
By connecting external capacitor, a
voltage feedback amplifier is formed.
The gain of it is determined by
capacitor’s value.
Connect a photodiode to supply a
signal to the internal comparator.
A strobe voltage output, referenced to
VDD.
When output = VDD -5V, it enables
other internal circuits.
To supply the power
To output pulse drive signal for external
NPN transistor which drives a IR
photodiode.
It can be used to connect up to 40
detectors to make auxiliary alarm,
remote alarm, auto-dialer…
Push-pull driver outputs signal to drive
external buzzer to alarm, and to show
various operation states.
To feed ‘silver’ signal back to the
push-pull output driver circuit’s input
It is an open drain output, can drive
LED directly. The LED can tell the
detector’s various operation states.
Connected to external R and C, which
determine the internal oscillator’s
frequency.
Connected to external R and C, which
determine the output pulse period of
IRED.
It connected to external resistor divider
between VDD and LED to get a low
supply alarm threshold voltage
This pin is normally low by an internal
pull-down device. When it is set high,
the IC enters into a simulated-smoke
condition. When floating, this pin
comes back to VSS (low) by pull-down
device.
3
DETECT
4
5,14
6
STROBE
VDD, GND
IRED
O
Strobe
Power supply
O
Output signal
7
I/O
BRASS,
SILVER
FEEDBACK
LED
Input/output
Push-pull
output
driver’s
8,9
10
11
O
I
O
Feedback terminal
Output signal
12
OSC
I
Oscillator’s input
External R and C
connecting
terminal
13
R1
15
LOW-SUPPLY
I
Low
voltage
detecting input
16
TEST
I
Test terminal
6. Function of this IC:
6.1. The variable gain photoelectric amplifier is directly connected to IR detector (photodiode).
The amplifier’s gain is determined by external capacitors C1 and C2. During standby, the
amplifier’s gain is at minimum. Under smoke condition, the amplifier’s gain is at medium.
Entering into test condition, the amplifier’s gain is at maximum. Additionally, under standby
state, if the special supervisory circuit is activated to check the chamber’s sensitivity, the
amplifier’s gain is also at its maximum.
6.2. Using VSS as its reference, the I/O pin can be used to connect up to 40 units together.
When I/O pin is used as an input, its on-chip pull-down resistor can prevent noise from entering
http://www.belling.com.cn
-2-
8/28/2006
Wrote by 2006
Total
8 Pages
BELLING [ SHANGHAI BELLING CO., LTD. ]
