SN74AHC123A屬于集成電路（IC）的多諧振蕩器。由美國(guó)德州儀器公司制造生產(chǎn)的SN74AHC123A多諧振蕩器多諧振蕩器是簡(jiǎn)單的雙態(tài)器件，盡管它們的典型使用方式在很大程度上具有模擬特性，但通常被認(rèn)為是數(shù)字邏輯元器件。單穩(wěn)型也稱為“單發(fā)”，具有一種穩(wěn)定狀態(tài)；但施加觸發(fā)信號(hào)可使它們離開此狀態(tài)一段時(shí)間，該時(shí)間通常由所連接電容器的值來確定。這些器件對(duì)于去彈跳開關(guān)觸頭等應(yīng)用非常有用。非穩(wěn)型沒有穩(wěn)定狀態(tài)，在兩個(gè)狀態(tài)之間按一定頻率持續(xù)轉(zhuǎn)換，該頻率通常也是由所連接電容器的值來確定。

FEATURES

· Controlled Baseline

– One Assembly Site

– One Test Site

– One Fabrication Site

· Extended Temperature Performance of –55°C

to 125°C

· Enhanced Diminishing Manufacturing Sources

(DMS) Support

· Enhanced Product-Change Notification

· Qualification Pedigree (1)

· Operating Range 2-V to 5.5-V VCC

· Schmitt-Trigger Circuitry On A, B, and CLR

Inputs for Slow Input Transition Rates

· Edge Triggered From Active-High or

Active-Low Gated Logic Inputs

· Retriggerable for Long Output Pulses

· Overriding Clear Terminates Output Pulse

· Glitch-Free Power-Up Reset On Outputs

· Latch-Up Performance Exceeds 100 mA Per

JESD 78, Class II

· ESD Protection Exceeds JESD 22

– 2000-V Human-Body Model (A114-A)

– 200-V Machine Model (A115-A)

– 1000-V Charged-Device Model (C101)

DESCRIPTION/ORDERING INFORMATION

The SN74AHC123A device is a dual retriggerable monostable multivibrator designed for 2-V to 5.5-V VCC

operation.

This edge-triggered multivibrator features output pulse-duration control by three methods. In the first method, the

A input is low, and the B input goes high. In the second method, the B input is high, and the A input goes low. In

the third method, the A input is low, the B input is high, and the clear (CLR) input goes high.

The output pulse duration is programmed by selecting external resistance and capacitance values. The external

timing capacitor must be connected between Cext and Rext/Cext (positive) and an external resistor connected

between Rext/Cext and VCC. To obtain variable pulse durations, connect an external variable resistance between

Rext/Cext and VCC. The output pulse duration can be reduced by taking CLR low.

Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input

pulse. The A, B, and CLR inputs have Schmitt triggers with sufficient hysteresis to handle slow input transition

rates with jitter-free triggering at the outputs.

Once triggered, the basic pulse duration can be extended by retriggering the gated low-level-active (A) or

high-level-active (B) input. Pulse duration can be reduced by taking CLR low. CLR can be used to override A or

B inputs. The input/output timing diagram illustrates pulse control by retriggering the inputs and early clearing.

The variance in output pulse duration from device to device is less than ±0.5% (typ) for given external timing

components. An example of this distribution for the SN74AHC123A is shown in Figure 10. Variations in output

pulse duration versus supply voltage and temperature are shown in Figure 6.