View A5303SLE-T_4980969.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
Features and Benefits
Low average standby current allows 10-year battery life 2.3 to 5.5 V operating range Interconnect option Logic outputs to control an external sound IC Low battery detection and warning Chamber sensitivity test and warning Triple horn-chirp to distinguish chamber warning Power-on reset (POR) Digital filter on I/O provides significant noise immunity Timer (hush) mode for enabling reduced sensitivity period Built-in circuits to reduce false triggering ESD protection circuitry on all pins Temporal Horn Pattern, per UL217, NFPA72, ISO8201 Latching alarm indicator identifies alarm-initiating devices
Description
The A5303 is a low-current BiCMOS photoelectric smoke detector circuit with ultra-low standby current and can operate for 10 years powered by inexpensive batteries. This device can be used with an infrared optical chamber to sense light scattered from smoke particles. A networking capability allows units to be interconnected so that if any unit senses smoke all units will sound an alarm. Special features are incorporated in the design to facilitate calibration and testing of the finished detector. A variable-gain photoamplifier can be directly interfaced to an infrared emitter-detector pair. The amplifier gain levels are determined by two external capacitors and are internally selected depending on the operating mode. Low gain is selected during standby and timer modes. During a local alarm, this low gain is increased (internally) by approximately 45% to provide hysteresis. High gain is used during pushbutton test and to periodically monitor the chamber sensitivity during standby. The internal oscillator and timing circuitry minimize standby power by sensing for smoke for only 100 s once every 10 s. A special three-stage-speedup sensing scheme is incorporated to minimize the time to an audible alarm and also to reduce false triggering. Chamber sensitivity is periodically monitored and two consecutive cycles of degraded sensitivity are required for a warning signal to occur. The A5303 is supplied in a thin profile (<1.2 mm overall height) 20-pin TSSOP package (0.65 mm nominal lead pitch). The package is lead (Pb) free with 100% matte tin leadframe plating.
Package: 20-pin TSSOP (suffix LE)
Not to scale
Typical Application Diagram
To / from other units VDD 56 nF C1 R1 3 k 5.6 nF 560 C2 220 VDD VDD 1.2 V VDD 10 F LVSET Low Batt Low Batt Sample TEST DETECT Smoke Chamber 1 k VDD 100 F 3 HUSH Connect HUSH to VSS to disable timer mode OSC Timing VSS IRED ISET LED Red LED OSCCAP 1500 pf TRES 100 k 10 STROBE Control Logic BLINK VDD 1.6 V SOUT0 SOUT1 SOUT2 HORN 3V
I/O
Gain Select
A
Push-to-test
Connect to allow timer (hush) mode operation
5 k R2
200 k
B
Voice IC outputs
A
A resistor connected between this pin and VDD or VSS adjusts the low-battery threshold In standby, BLINK = VDD causes LED to blink, BLINK = V SS causes LED not to blink
B
Output to optional boost converter to drive a piezo horn
5303-DS
A5303
Selection Guide
Part Number A5303SLE-T A5303SLETR-T
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
Pb-free and RoHS Yes Yes Package 20-pin TSSOP (JEDEC MO-153AC) 20-pin TSSOP (JEDEC MO-153AC) Packing 75 pieces / tube 4000 pieces / reel
Absolute Maximum Ratings
Characteristic Supply Voltage Range DC Input Voltage Range Operating Ambient Temperature Range Maximum Junction Temperature Storage Temperature Range Symbol VDD VIN TA TJ(max) Tstg Referenced to VSS Referenced to VSS Allegro Range S Notes Rating -2.3 to 6 -0.3 to 6 -20 to 85 150 -55 to 150 Units V V C C C
Thermal Characteristics
Characteristic Package Thermal Resistance Symbol RJA Test Conditions* Estimated, single-layer PCB, minimal exposed copper area Value 127 Units C/W
*Additional thermal information available on Allegro website.
Terminal List
Number Name SOUT1 SOUT0 I/O BLINK HUSH ISET VDD IRED STROBE DETECT C2 C1 LVSET TRES VSS OSC CAP TEST HORN LED SOUT2 Function Logic push-pull output for controlling an external sound IC Logic push-pull output for controlling an external sound IC Input-output to interconnected detectors Logic input for enabling/disabling the LED blink during standby Input for photoamplifier timer mode reference; can also disable timer mode A resistor on this pin connected to VSS sets the IRED output current Positive supply voltage Terminal to drive smoke chamber IR LED Strobed supply (VDD - 2 V) for photoamplifier low-side reference Photoamplifier input Sets photoamplifier gain in standby mode Sets photoamplifier gain in supervisory mode Optionally used with a resistor to adjust the low-battery threshold Connection for resistor to set clock times/frequency Negative supply voltage Connection for capacitor and resistor to set clock times/frequency Enables push-to-test mode; starts timer mode, if enabled Logic output which optionally enables a boost converter to drive a horn Output to drive visible LED Logic push-pull output for controlling an external sound IC
Pin-out Diagram
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
SOUT1 1 SOUT0 2 I/O 3 BLINK 4 HUSH 5 ISET 6 VDD 7 IRED 8 STROBE 9 DETECT 10
20 SOUT2 19 LED 18 HORN 17 TEST 16 OSC CAP 15 VSS 14 TRES 13 LVSET 12 C1 11 C2
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
2
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
DC ELECTRICAL CHARACTERISTICS1 Valid at TA = 25C, VDD = 2.3 to 5.5 V, configured as in Typical Application Diagram
(unless otherwise noted)
Supply Voltage Range Operating Supply Current Characteristics Symbol VDD IDD Operating During standby, STROBE off During STROBE on, IRED off During STROBE on, IRED on Input Current TEST Pulldown Current Logic Voltage Low Logic Voltage High IIN IIN(TEST) VI(L) VI(H) Inactive Strobe Output Voltage Line Regulation Strobe Temperature Coefficient Maximum IRED Current Setting IRED Current IRED Temperature Coefficient LED Drive Current Low-Battery Warning Threshold Low-Battery Warning Minimum Common Mode Voltage Smoke Comparator Reference Voltage I/O Input Impedance I/O Output Impedance
1Limits
Test Conditions
Min. 2.3 - - - -100 - - VDD x 0.7 - VDD - 2.1 - - - 89 - 0.6 2.4 1.8 VDD - 1.0 - 40 -
Typ.2 3.0 2.3 210 220 0 3.5 - - VDD VDD - 2.0 -60 0.01 - 100 0.40 1.2 2.5
Max. 5.5 5.0 300 300 100 - VDD x 0.3 - - VDD - 1.9 - - 300 111 - 1.8 2.6 VDD - 0.3 - - 5.7
Unit V A A A nA A V V V V dB % / C mA mA % / C mA V V
BLINK, C1, C2, DETECT, OSC CAP, TRES (pulldown off) VTEST = VDD = 3 V
VST
Active, IO = 100 to 500 A
VST(VDD) Active, VDD = 2.3 to 5.5 V ST IIRED(MAX) IIRED IRED ILED VDD(th) VDD(warn) VIC VREF ZI/O(in) ZI/O(out) VSTROBE, VDD = 2.3 to 5.5 V Current is set by selection of resistor on ISET pin RISET = 3 IIRED, VDD = 2.3 to 5.5 V VLED = 0.5 V LVSET open VDD voltage guaranteed to operate SOUTx pins Photoamplifier input Any alarm condition, except hush mode No alarm conditions Local or test alarm
- VDD - 1.6 83 3.9
V V k k
over the operating temperature range are based on characterization data. Characteristics are production tested at 25C only. 2Typical values are at 25C and are given for circuit design information only.
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
3
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
AC ELECTRICAL CHARACTERISTICS1 Valid at TA = 25C, VDD = 2.3 to 5.5 V, configured as in Typical Application Diagram
(unless otherwise noted)
Characteristics Oscillator Period Smoke Check Low Battery Test Degraded Chamber Test Symbol tosc tsmoke tbattery tbattery2 tchamber tchamber2 tled0 tled1 LED Pulse Period tled3 tled4 tled6 tled7 LED Pulse Width LED Pulse Spacing tw(led) tsp(led) tst1 tst2 STROBE Pulse Period tst3 tst4 tst5 tst6 STROBE Pulse Width tw(st) tired1 tired2 IRED Pulse Period tired3 tired4 tired5 tired6 IRED Pulse Width I/O to Active Delay I/O Charge Dump Duration Rising Edge on I/O to Alarm tw(ired) td(io) tdump tr(io) Local alarm End of local alarm or test No local alarm No local or remote smoke After 1 of 3 valid samples After 2 of 3 valid samples and during local alarm Remote smoke only Chamber test, no local alarm Pushbutton test, induced alarm 3 pulses, degraded chamber No local or remote smoke After 1 of 3 valid samples After 2 of 3 valid samples and during local alarm Remote smoke only Chamber test, no local alarm Pushbutton test, induced alarm No low-battery detected Low-battery detected No degraded chamber detected Degraded chamber detected No local or remote smoke, BLINK = VSS No local or remote smoke, BLINK = VDD Local smoke Remote smoke only Pushbutton test, induced alarm Timer mode, no alarm Test Conditions OSC Count 1 210 218 212 218 212 - 212 48 - 48 210 1 26 210 192 96 768 218 24 1 210 192 96 768 218 24 0.01 - 96 9 to 13 Min. 9.4 9.6 41.3 39 41.3 39 - 39 0.45 - 0.45 9.67 9.5 0.60 9.6 1.8 0.8 7.2 41.3 225 9.5 9.6 1.8 0.8 7.2 41.3 225 94 - 0.9 9x tosc Typ.2 10.5 10.75 45.9 43 45.9 43 No LED Pulses 43 0.50 No LED Pulses 0.50 10.75 10.5 0.67 10.75 2.0 1.0 8.0 45.9 252 10.5 10.75 2.0 1.0 8.0 45.9 252 105 0 1.0 94.5 - 137 Max. 11.5 11.9 50.5 48 50.5 48 - 48 0.55 - 0.55 11.83 11.5 0.74 11.9 2.2 1.1 8.9 50.5 278 11.5 11.9 2.2 1.1 8.9 50.5 278 116 - 1.1 13 x tosc Unit ms s min s min s - s s - s s ms s s s s s min ms ms s s s s min ms s s s ms
Continued on the next page...
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
4
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
AC ELECTRICAL CHARACTERISTICS (continued)1 Valid at TA = 25C, VDD = 2.3 to 5.5 V, configured as in Typical Application
Diagram (unless otherwise noted)
Characteristics SOUTx Output Warning Period SOUTx Output Warning Pulse Width Horn Warning Pulse Period Horn Warning Pulse Width Horn Warning Pulse Spacing Horn On-Time Symbol tsoutx tw(soutx) thorn tw(horn) tsp(horn) ton(horn) toff1(horn) Horn Off-Time toff2(horn) Timer Mode Duration Failed Push-Test Indication on SOUTx
1Limits 2Typical
Test Conditions Low supply or degraded chamber Low supply or degraded chamber Low battery or degraded chamber Low battery or degraded chamber 3 chirps, degraded chamber Local, remote, or test alarm Local, remote, or test alarm (see Timing Diagrams section) Local, remote, or test alarm (see Timing Diagrams section)
OSC Count 212 1 212 1 26 48 48 144 57344
Min. 38.9 9.5 38.9 9.5 0.60 450 450 1350 9.0 211 x tosc
Typ.2 43 10.5 43 10.5 0.67 500 500 1500 10.0 21.5 - 32.3
Max. 47.1 11.5 47.1 11.5 0.74 550 550 1650 11.0 3072 x tosc
Unit s ms s ms s ms ms ms min s
ttimer tFAIL After TEST input goes low
211
to 3072
over the operating temperature range are based on characterization data. Characteristics are production tested at 25C only. values are at 25C and are given for circuit design information only.
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
5
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
Pin and Circuit Description
(In Typical Application)
C1 Pin A capacitor connected to this pin determines the gain of the photoamplifier, Ae , during the push-to-test mode and during the chamber monitor test. A typical capacitor value for this highgain (supervisory) mode is 0.047 F, but it should be selected based on the photochamber background reflections reaching the detector and the required level of sensitivity. Ae = 1 + (C1 / 12), where C1 is in pF. Ae should not exceed 10,000 and thus C1 should not exceed 0.1 F. Coupling of other signals to the C1, C2, and DETECT inputs must be minimized. C2 Pin A capacitor connected to this pin determines the gain of the photoamplifier, Ae, during standby. A typical capacitor value for this low-gain mode is 4700 pF, but it should be selected based on a specific photochamber and the desired level of sensitivity to smoke. Ae = 1 + (C2 / 12), where C2 is in pF. Ae should not exceed 10,000 and thus C2 should not exceed 0.1 F. This gain increases by a nominal 45% after a local alarm is detected (three consecutive detections). A resistor must be installed in series with the C2 capacitor. DETECT Pin This is the input to the photoamplifier and is connected to the cathode of the photodiode. The photodiode is operated at zero bias and should have low dark leakage current and low capacitance. A shunt resistor must be installed in parallel with the photodiode. STROBE Pin This output provides a strobed, regulated voltage of VDD - 2 V. The minus side of all internal and external photoamplifier circuitry is referenced to this pin. VDD Pin This pin is connected to the positive supply potential, typically 3 V. LVSET Pin This pin allows the user to externally adjust the low-battery alarm threshold. To increase the threshold, a resistor can be connected between LVSET and VDD. To decrease the threshold, a resistor can be connected between LVSET and VSS. IRED Pin This output provides a pulsed drive current for the external IR emitter. To minimize noise impact, the IRED is not active when
the visible LED output is active. ISET Pin This pin allows the user to externally set the IRED current by connecting a resistor between it and VSS. The IRED current controls the amount of light generated by the IR LED in the chamber. The IRED current, in mA, can be approximated using the following equation: IIRED (mA) = 300 / RISET (1) The chosen resistor should set a maximum of 300 mA (typically a minimum of 1). I/O Pin A connection at this pin allows multiple smoke detectors to be interconnected. If any single unit detects smoke, its I/O pin is driven high, and all connected units will sound their associated alarm indicators. As an input, this pin is sampled every 4 clock cycles (nominally 43 ms) during standby, and two consecutive samples and one additional clock with I/O high are required before signaling an alarm. If the I/O line goes low at all during the 96.8 ms, the remote alarm is not enabled, providing significant immunity to I/O noise and other pulses on the I/O line which are shorter than 9 clock cycles. The LED is suppressed when an alarm is signaled from an interconnected unit, and any local-alarm condition causes this pin to be ignored as an input. An internal NMOS device acts as a charge dump to aid in applications involving a large (distributed) capacitance, and is activated at the end of a local or test alarm. This pin has an on-chip pull-down device and must be left unconnected if not used. In the application, there should be a series current-limiting resistor to other smoke alarms. SOUT0, SOUT1, SOUT2 Pins These pins provide push-pull CMOS logic outputs to control an external sound IC. The outputs indicate the state of the device as follows:
Condition Standby Local Alarm Remote Alarm Push-Test Passed Push-Test Failed Low-Battery Degraded Chamber SOUT2 L L L L H H H SOUT1 L L H H L L H SOUT0 L H L H L H L
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
6
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
HORN Pin The HORN pin is a logic output provided to enable an optional, external boost converter that can drive a piezoelectric (piezo) horn. Using a boost converter to drive a piezo horn allows alarms to generate high SPL levels from low supply voltages. HORN will be driven high to enable the boost converter. The output of the boost converter will be connected to the piezo horn such that the horn will sound when the converter is enabled. If a boost converter and horn are not used, this pin should be left open. BLINK Pin This logic input determines the LED operation while the device is in standby. If BLINK is connected to VDD the device will blink once every approximately 43 s in standby. If BLINK is connected to VSS the device will not blink in standby. If a low-battery or degraded-chamber condition exists while the device is in standby, the LED will blink as described in the Alarm Indications section, regardless of the state of the BLINK pin. The BLINK pin has no effect when the device is in local, remote, or test alarm. LED Pin This open-drain NMOS output is used to directly drive a visible LED. The LED indicates detector status as follows (with component values as in the typical application, all times nominal):
Condition Standby, BLINK = VDD Standby, BLINK = VSS Local Smoke Remote Alarm Test Mode Timer (Hush) Mode Pulse Occurrence Every 43.0 s No LED pulses Every 0.5 s No pulses Every 0.5 s Every 10.8 s
nominally 105 s. The internal clock high time can be calculated by: Thigh = 0.693 x RTRES x COSCCAP (3) VSS Pin This pin is connected to the negative supply potential (usually ground). HUSH Pin This input pin serves two purposes in standby mode. It serves to enable/disable entering the internal 10-minute (nominal) "hush" timer mode, and also as the reference for the smoke comparator during timer mode. Timer mode allows the user to temporarily hush alarms caused by nuisance smoke or steam (such as from cooking). When the voltage on this pin is greater than approximately 50 mV, entering timer mode is enabled, and a high-to-low transition on the TEST pin resets and starts timer mode. If use of timer mode is not desired this pin must be connected to VSS, and timer mode is disabled. During timer mode the smoke comparator reference is established externally by a resistive divider (R1 and R2) between VDD and STROBE. Also, during timer mode the photoamplifier gain, Ae, is internally reduced to about 55% that during the normal-gain mode. Thus, Ae = 1 + (C2 / 22), where C2 is in pF. These two conditions allow the detector to operate with reduced sensitivity during timer mode. If the level of smoke increases such that the temporary alarm threshold is reached, a local alarm will sound. If the HUSH pin is connected directly to STROBE without using a resistor divider, then a local alarm will never occur during timer mode, regardless of the smoke level. When not in timer mode, the smoke comparator reference is set internally to approximately VDD - 1.6 V. The resistor dividers formed by the adjustable photoamp-divider and the HUSH divider (R1 + R2, if timer mode is used) should be chosen so that the load on STROBE does not exceed 500 A. Thus, the photoamp-divider (8 k in the typical application) in parallel with the HUSH divider (R1 + R2) shall be no less than 4 k.
OSC CAP (Oscillator Capacitor) Pin A capacitor between this pin and VDD, along with a parallel resistor, forms part of a two-terminal oscillator and sets the internal clock low time. With component values shown, this nominal time is 10.4 ms and essentially the oscillator period, which is also the STROBE pulse width. The internal clock low time can be calculated by: Tlow = 0.693 x ROSCCAP x COSCCAP (2)
TEST Pin This pin has an internal pulldown device and is used to manually invoke push-to-test mode and timer mode. Push-to-test mode is TRES (Timing Resistor) Pin A resistor between this pin and OSC CAP is part of the two-termi- initiated by a voltage greater than approximately VDD - 0.5 V on this pin (usually the closure of a normally open push-button nal oscillator and sets the internal clock high time, which is also the IRED pulse width. With component values shown, this time is switch to VDD). After one oscillator cycle, the amplifier gain is
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
7
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
latched alarm condition will cease after 24 hours to preserve battery life, and to prevent masking future latched alarm indications. Alarm Indications Alarm conditions include: local smoke detection, a remote alarm, low battery, and degraded chamber sensitivity. These are indicated by a combination of SOUTx output, piezo horn, and LED signals, which continue until the alarm condition is resolved. A local alarm always overrides a remote alarm and a push-test. Remote alarm always overrides a push-test. A local alarm, remote alarm, or a push-test will inhibit warning signals for low battery or degraded chamber. During a local or a remote alarm condition, the device continuously signals an alarm condition on the SOUTx pins that indicates the type of the alarm. The piezo horn output is a continuous modulated tone (temporal horn pattern), nominally: 0.5 s on, 0.5 s off, 0.5 s on, 0.5 s off, 0.5 s on, and 1.5 s off. The visible LED also distinguishes a local alarm from a remote alarm. During a
increased by internal selection of C1 so that background reflections in the smoke chamber can be used to simulate a smoke condition, and IRED pulses every 252 ms (nominal). After the third IRED pulse (three consecutive simulated smoke conditions), the successful test signals a continuous passing-test-alarm condition to the sound IC, outputs the temporal pattern to the piezo horn, and activates the I/O pin. When the pushbutton is released, the input returns to VSS due to the internal pulldown. After one oscillator cycle, the amplifier gain returns to normal, and after three additional IRED pulses (less than one second), the device exits this mode and returns to standby. This high-to-low transition on TEST also resets and starts the 10-minute (nominal) "hush" timer mode, if the mode is enabled via the HUSH pin. The high-to-low transition also resets the latching alarm indicator, if it is latched. If the chamber malfunctions or is too dirty, the push-test will fail to simulate a smoke condition, and after three failed STROBE pulses the device signals a continuous failing-test-alarm condition on the SOUTx pins. The piezo driver and the I/O pins are not enabled. Diagnostic Test/Calibration mode is available to facilitate calibration and test of the IC and the assembled detector. It is initiated by pulling TEST below VSS by continuously drawing 200 A from the pin for at least one clock cycle on OSC CAP. The current should not exceed 500 A and under these conditions, TEST pin voltage will clamp at approximately 250 mV below VSS. One option is to connect TEST to a -5 V supply through a 15 k resistor. In this mode, certain device pins are reconfigured as described in table 1. The IRED pulse rate is increased to one pulse every OSC CAP cycle and the STROBE pin is always active. To exit this mode, the TEST pin should be floated, or returned to VSS, for at least one OSC CAP cycle. Latching Alarm Indicator When multiple smoke detectors are networked through the I/O line, the latching alarm indicator allows the user to identify which detector(s) initiated an alarm. When a local alarm condition occurs, the initiating detector(s) will latch the event in memory. After the alarm condition has expired (the device stops signaling the alarm condition to the sound IC) the initiating detector(s) will output an additional 10 ms LED pulse every 43 seconds. If the BLINK pin is connected to VDD, the additional pulse will occur 0.67 seconds after the normal standby pulse. The user can clear the latched alarm condition by pressing and releasing the push-totest button. If the user does not press the push-to-test button, the
Table 1. Alternate Pin Configuration During Diagnostic Test/Calibration Mode
Pin Name I/O Alternate Configuration Disabled as an output. A logic high on this pin places the photoamplifier output on the BLINK pin. The amplifier output appears as pulses. If the I/O pin is high, this pin controls the amplifier gain capacitor. If this pin is low, normal gain is selected. If this pin is high, supervisory gain is selected. NOTE: If I/O is low, clocking this pin will cause the device to exit diagnostic/calibration mode and enter an Allegro-defined test mode. If the I/O pin is high, this pin is reconfigured as the photoamplifier output. If the I/O pin is high and the HUSH pin is low (normal gain), taking this pin to a high logic level increases the amplifier gain by 45% (hysteresis). This pin is reconfigured as the smoke integrator output. Three consecutive smoke detections will cause this pin to go high and three consecutive no-smoke detections cause this pin to go low. This pin becomes a low-battery indicator. The opendrain NMOS output is normally off. If VDD falls below the low-battery threshold, the output turns on. This pin may be driven by an external clock source. Driving this pin low and high drives the internal clock low and high. The external RC network may remain intact.
HUSH
BLINK SOUT0
SOUT2
LED
OSC CAP
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
8
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
local alarm, the LED blinks every 0.5 s (nominally), but during a remote alarm, the LED is disabled and does not blink. The degraded-chamber test occurs periodically (nominally every 45.9 min). During this test, the gain of the photoamplifier is switched to the high (supervisory) level, set by C1. The device expects that the photodiode will receive enough background reflections in the chamber to cause an alarm condition. If a faulty, dirty, or obstructed chamber prevents this during a test, the test period decreases to 43 s. After two consecutive failed tests, the device signals a degraded chamber condition to the sound IC. It also chirps the horn and pulses the LED three times every 43 seconds. The condition is resolved when the chamber is either
cleared or cleaned, and the test period then reverts to (nominally) 45.9 min. The low-battery test also occurs periodically (also nominally every 45.9 min, but at a different time than the degraded-chamber test). During this test a resistive divider off VDD is compared to an internal band-gap reference. If VDD is below the threshold, the device signals a low battery condition to the sound IC and the test period decreases to 43 s. It also chirps the horn and pulses the LED once every 43 seconds. The condition is resolved when the battery is replaced and the test period then reverts to (nominally) 45.9 min.
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
9
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
Timing Diagrams
(Not to Scale)
Standby Mode
OSC CAP
Test event tw(ired)
Internal clock
tosc tsmoke, tst1, tired1 tbattery, tled0, tst5, tired5
Photo sample Low-battery test Chamber test
tw(st) tchamber, tst5, tired5
STROBE IRED
tled1 tw(led)
LED, BLINK = VDD LED, BLINK = VSS
(LED OFF)
Low Battery Condition
VDD
tbattery tbattery2 tsoutx (Low battery) tbattery2 tw(soutx) tbattery
Low-battery test SOUTx HORN
tled1 tw(horn)
SOUT(2:0) = (HLH)
thorn tw(horn)
LED
these two pulses will not exist if BLINK = VSS
Degraded Chamber Condition
Chamber sensitivity Chamber test SOUTx HORN
tsp(led) tsp(horn) tchamber tchamber2 tsoutx (Degraded chamber) tchamber2 tw(soutx) tchamber
SOUT(2:0) = (HHL)
thorn tw(horn)
LED
tw(led)
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
10
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
Local Smoke Detection Condition
Chamber
(smoke present)
1st strobe with smoke 3rd strobe with smoke 3rd strobe without smoke
IRED
tst2,ired2 tst3,ired3 tw(st)
STROBE
tw(led)
LED
BLINK = VSS or VDD
tst3,ired3
tled3
SOUTx
ton(horn)
SOUT(2:0) = (LLH)
toff2(horn) toff1(horn)
HORN
tdump
I/O
(OUTPUT)
I/O charge dump
Remote Alarm Condition
LED
BLINK = VSS or VDD
(LED OFF)
tw(st) tst4,ired4
STROBE SOUTx
ton(horn)
SOUT(2:0) = (LHL)
toff2(horn) toff1(horn)
HORN
tr(io)
I/O
(INPUT)
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
11
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
Test Alarm Mode (passing)
LED
BLINK = VSS or VDD
tw(led)
tled6
STROBE
tw(st) tst6,ired6
TEST SOUTx
ton(horn)
SOUT(2:0) = (LHH)
toff2(horn) toff1(horn)
HORN
tdump
I/O
(OUTPUT)
I/O charge dump
Test Alarm Mode (failing)
LED
BLINK = VSS or VDD
tw(led)
tw(st)
STROBE TEST SOUTx HORN I/O
SOUT(2:0) = (HLL)
tFAIL
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
12
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
Package LE, 20-Pin TSSOP
6.500.10 20
0.45 8 0 0.20 0.09 1.70 20
0.65
4.400.10 A
6.400.20 0.60 0.15 1.00 REF
6.10
1
2 0.25 BSC 1 2
20X 0.10 C 0.30 0.19
SEATING PLANE 1.20 MAX 0.15 0.00
C
SEATING PLANE GAUGE PLANE B PCB Layout Reference View
0.65 BSC
For Reference Only; not for tooling use (reference MO-153 AC) Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown A Terminal #1 mark area B Reference land pattern layout (reference IPC7351 SOP65P640X110-21M); All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances; when mounting on a multilayer PCB, thermal vias at the exposed thermal pad land can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5)
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
13
A5303
Photoelectric Smoke Detector with Interconnect, Timer, and Latching Alarm Indicator
Allegro MicroSystems offers an industry-leading range of ionization and photoelectric smoke detector ICs. For a current listing, please visit our website at:
www.allegromicro.com
Copyright (c)2001-2010, Allegro MicroSystems, Inc. The products described herein are manufactured under one or more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283; 5,389,889; 5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents pending. Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro's products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. For the latest version of this document, visit our website: www.allegromicro.com
Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com
14

▲Up To Search▲

Price & Availability of A5303SLE-T

	To Download A5303SLE-T Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .