HEF4938B
Key Features
- Separate reset inputs
- Triggering from leading or trailing edge
- ICC category: MSI DESCRIPTION The HEF4938B is a dual retriggerable-resettable monostable multivibrator. Each multivibrator has an active LOW trigger/retrigger input (I0), an active HIGH trigger/retrigger input (I1), an overriding active LOW direct reset input (CD), an output (O) and its complement (O), and two pins (CTC and RCTC) for connecting the external timing components Ct and Rt. Typical pulse width variation over temperature range is ±0.2%. The HEF4938B may be triggered by either the positive or the negative edges of the input pulse and will produce an accurate output pulse with a pulse width range of 10 µs to infinity. The duration and accuracy of the output pulse are determined by the external timing components Ct and Rt. The output pulse width (T) is equal to Rt × Ct. The linear design techniques in LOCMOS guarantee precise control of the output pulse width. A LOW level at CD terminates the output pulse immediately. Schmitt-trigger action in the inputs makes the circuit highly tolerant for slower rise and fall times. FUNCTION TABLE INPUTS I0 ↑ H X Notes 1. H = HIGH voltage level 2. L = LOW voltage level January 1995 I1 L ↑ X CD H H L L H 3. X = state is immaterial 4. ↑ = positive-going transition 5. ↓ = negative-going transition 6. 7. = positive output pulse = negative output pulse 2 OUTPUTS O O TYPE NUMBER PINS HEF4938B PIN DESCRIPTION PIN NO. 1, 15 2, 14 3, 13 4, 12 5, 11 6, 10 7, 9 8 16 SYMBOL CTC A, CTC B RCTC A, RCTC B CDA, CDB I1A, I1B I0A, I0B OA, OB OA, OB VSS VDD 16 PIN POSITION DIL ORDERING AND PACKAGE INFORMATION PACKAGES HEF4938B
