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参数资料
| 型号： | A5348CA |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 5/9页 |
| 文件大小： | 0K |
| 描述： | IC SMOKE DETECTOR ION 16-DIP |
| 标准包装： | 25 |
| 类型： | 烟雾探测器 |
| 输入类型： | 离子化 |
| 输出类型： | 电压 |
| 电流 - 电源： | 12µA |
| 安装类型： | 通孔 |
| 封装/外壳： | 16-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 16-DIP |
| 包装： | 管件 |
Ionization Smoke Detector
with Interconnect and Timer
A5348
5
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
The A5348 is a low-current, BiCMOS circuit providing all of the
required features for an ionization-type smoke detector.
Oscillator
An internal oscillator operates with a period of 1.67 seconds
during no-smoke conditions. Every 1.67 seconds, internal power
is applied to the entire circuit for 10 ms and a check is made for
smoke. Every 24 clock cycles (approximately 40 seconds), the
LED pin is pulsed and a check is made for low battery by com-
paring VDD to an internal reference. Because very-low currents
are used in the device, the oscillator capacitor at the OSC CAP
pin should be a low-leakage type (PTFE, polystyrene, or polypro-
pylene).
Detector Circuitry
When the voltage on the DETECT IN pin is less than the volt-
age on the SENSITIVITY SET pin, the A5348 evaluates this as a
smoke condition. During a smoke condition, the resistor divider
network that sets the sensitivity (also referred to as the smoke trip
point) is altered to increase VSENSITIVITYSET by 130 mV typical
(with no external connections on the SENSITIVITY SET pin).
This provides hysteresis and reduces false triggering.
An active guard is provided on GUARD1 and GUARD2, the two
pins adjacent to the detector input, the DETECT IN pin. VGUARD1
and VGUARD2 will be within 100 mV of VDETECTIN. This will
keep surface leakage currents to a minimum and provide a
method of measuring the input voltage without loading the ion-
ization chamber. The active guard amplifier is not power strobed
and thus provides constant protection from surface leakage
currents. The detector input has internal diode protection against
electrostatic damage.
Alarm Circuitry
If smoke is detected, the oscillator period changes to 40 ms and
the horn is enabled. The horn output is typically 160 ms on,
80 ms off. During the off-time, smoke is checked and further
alarm output will be inhibited if smoke is not sensed. During a
smoke condition, the low-battery alarm is inhibited and the LED
is pulsed approximately once every second.
Sensitivity Adjust
The detector sensitivity to smoke is set internally by a voltage
divider connected between VDD and VSS. The sensitivity can,
however, be externally adjusted to the individual characteristics
of the ionization chamber by connecting a resistor between the
SENSITIVITY SET pin and either the VDD or VSS pins.
With no external connections on the SENSITIVITY SET pin,
while the A5348 is checking for smoke:
VSENSITIVITYSET = VDD / 2 .
To increase sensitivity, a resistor can be connected between
SENSITIVITY SET and VDD, with the value:
RSENSITIVITYSET = 1.1E6 × K / (1 – K) ,
where
K = VDD / VSENSITIVITYSET – 1 .
To decrease sensitivity, a resistor can be connected between
Circuit Description
Characteristic
Symbol
Test Conditions
Test Pin
Min.
Typ.
Max.
Units
I/O Current
IIOL
No alarm, VI/O = VDD – 2.0 V
2
25
—
60
μA
IIOH
Local alarm, VI/O = VDD – 2.0 V
2
–7.5
—
mA
I/O Alarm Voltage
VIH(IO)
External “alarm” in
2
3.0
—
V
I/O Delay
tr(io)
Local or test alarm to I/O active
2
—
3.0
—
s
1Negative current is dened as coming out of the specied device pin (sourcing).
2Alarm (smoke) condition is dened as VDETECTIN < VSENSITIVITYSET; no alarm (no smoke) condition is dened as VDETECTIN > VSENSITIVITYSET.
ELECTRICAL CHARACTERISTICS1,2
(continued) at TA = 25°C, VDD = 9.0 V, VSS = 0 V, COSCCAP = 0.1 μF,
RTIMINGRES = 8.2 MΩ (unless otherwise noted)
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相关代理商/技术参数 |
参数描述 |
|---|---|
| A5348CA-T | 功能描述:IC SMOKE DETECTOR ION 16-DIP RoHS:是 类别:集成电路 (IC) >> 接口 - 传感器和探测器接口 系列:- 其它有关文件:Automotive Product Guide 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:74 系列:- 类型:触控式传感器 输入类型:数字 输出类型:数字 接口:JTAG，串行 电流 - 电源:100µA 安装类型:表面贴装 封装/外壳:20-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:20-TSSOP 包装:管件 |
| A5349CA | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:AC SMOKE DETECTOR WITH INTERCONNECT AND TIMER |
| A53506 | 制造商:n/a 功能描述:Ships in 2 days |
| A5350CA | 功能描述:IC SMOKE DETECTOR ION 16-DIP RoHS:否 类别:集成电路 (IC) >> 接口 - 传感器和探测器接口 系列:- 其它有关文件:Automotive Product Guide 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:74 系列:- 类型:触控式传感器 输入类型:数字 输出类型:数字 接口:JTAG，串行 电流 - 电源:100µA 安装类型:表面贴装 封装/外壳:20-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:20-TSSOP 包装:管件 |
| A5350CA-T | 功能描述:IC SMOKE DETECTOR ION 16-DIP RoHS:是 类别:集成电路 (IC) >> 接口 - 传感器和探测器接口 系列:- 其它有关文件:Automotive Product Guide 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:74 系列:- 类型:触控式传感器 输入类型:数字 输出类型:数字 接口:JTAG，串行 电流 - 电源:100µA 安装类型:表面贴装 封装/外壳:20-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:20-TSSOP 包装:管件 |
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