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参数资料
| 型号： | L9703 |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 电源管理 |
| 英文描述： | 8-CHANNEL POWER SUPPLY SUPPORT CKT, PDIP20 |
| 封装： | DIP-20 |
| 文件页数： | 5/9页 |
| 文件大小： | 1340K |
| 代理商： | L9703 |
FUNCTIONAL DESCRIPTION
The L9703 circuit monitors the status of the contacts
connected to ground and through this series exter-
nal resistors RIN to the contact sense input pins. The
contacts equivalent circuit is supposed to be as
shown in fig. 2.
The L9703 circuit compares the input current with
the current through the internal reference resistor.
The device is designed to work with an external input
series resistor of RIN1-8 = 1k
. With this input resistor
the contact current, when the contact is closed and
the device activated (EN = LOW) is
VS - 2V
IIN =
1k
(1)
For this calculation the limit value of the VS to IN
saturation voltage of 2V was considered so that the
lowest limit value of IIN is calculated in (1).
The function of the circuit can be demonstrated with
the transfer characteristics, showing the output
status as a function of the input resistor RI, shown
in figure 3. The input resistor is a sum of the RIN and
the contact resistance RCON or RCOFF, for the closed
contact :
RI = RIN + RCON,
(2)
and for the open contact :
RI = RIN + RCOFF.(3)
The output goes HIGH when the input resistance in-
creases above 5.3k
(typical value) and goes LOW,
when the input resistance decreases below 4k
(typical value). The limit values of RI = 1.8K
for
LOW and RI = 20k
for HIGH implies that a contact
with RCON = 100
(at IIN = 10mA) will be recognized
as ON = LOW and a contact with RCOFF = 19k
will
be recognized as OFF = HIGH. These limits are
valid within the supply voltage range 6V
≤ VS ≤ 16V
and
the
ground
potential
difference
of
VGND = 0,1V.
The internal clamping diodes at the contact moni-
toring inputs, together with the external contacts se-
ries resistors RIN, allows the device to withstand
transients at the contact connection. The contact se-
ries resistor RIN limits the input current at the tran-
sient.
The dynamic behaviour of the circuit is defined by
the times tdo and tdTs. When the contact is open, the
input capacitor CIN must be charged through the re-
sistor RIN. In this case the total delay time may also
be influenced by the time constant RINCIN.
The delay time tdTs, when disabling the device, is de-
fined only by the internal circuitry. In both cases, an
external output capacitance less than 50pF is as-
sumed, the internal output capacitances of the
three-state buffers are less than 5pF.
Figure 2 : The Contact Sense Input Connection with the Contact Equivalent Circuit.
L9703
5/9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| L9703D | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:OCTAL GROUND CONTACT MONITORING CIRCUIT |
| L9704 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:OCTAL SUPPLY CONTACT MONITORING CIRCUIT |
| L9704D | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:OCTAL SUPPLY CONTACT MONITORING CIRCUIT |
| L9705 | 功能描述:开关变换器、稳压器与控制器 Double Quad Interfac RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| L9705D | 功能描述:开关变换器、稳压器与控制器 Double Quad Interfac RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
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