Fairchild VHC VHCT Introduction and Data Handbook
Summary
Boost your designs with the VHC/VHCT logic family, a high-speed CMOS solution engineered for modern, mixed-voltage systems. This resource provides comprehensive details on implementing advanced digital electronics requiring superior speed and current drive compared to older standards. Ideal for circuit designers, it guarantees reliable functionality in low-voltage (3.3V) environments while offering robust features like over-voltage tolerance and noise immunity. Simplify design-in and maximize performance across diverse high-speed applications.
Page 1 Text Content
/V In tro ctio
February 1998 Revised April 1999
VHC/VHCT Introduction
Fairchild Semiconductor’s Very High-speed CMOS (VHC) tions. This feature is beneficial in mixed supply voltage logic family provides standard logic users a high-technol- applications where 5V logic is driving 3.3V VHC.
ogy upgrade from older logic families such as HCMOS.
VHCT options exist for many VHC functions similar to HCT
VHC delivers nearly three times the speed of comparable
options of HCMOS parts. For these parts input thresholds
HCMOS functions at twice the output current drive. Despite
have been adjusted to provide TTL levels of VILmax = 0.8V
the higher performance, power consumption and device
and VIHmin = 2.0V. This allows VHCT to be interfaced
generated noise is at or below that of HC making VHC
directly with TTL parts and sub-systems. VHCT versions
design-in simple and familiar. Enhanced datasheet specifi-
operate in a standard 4.5V to 5.5V TTL supply range.
cations such as output noise and power-down leakage fur-
ther simplify design-in. VHC is specified over a 2.0V to VHC/VHCT is a general purpose family available in a large 5.5V VCC range of operation. A complete set of 3.3V speci- number of gate, MSI and octal buffer functions. Package options include PDIP, JEDEC SOIC, EIAJ SOIC and
fications aid in today’s low voltage designs. VHC inputs are
TSSOP.
protected against over-voltage to 7.0V under all VCC condi-
Feature Benefit
3X faster than HCMOS Meets higher speed demands of new designs 2X the output current drive of HCMOS; ±8 m A Extends drive capability for on-board signal routing Guaranteed 3.3V specifications Eases design in low-voltage applications
Input over-voltage tolerant to 7.0V regardless of VCC Safely interfaces parts and sub-systems of differing supply voltages
Guaranteed noise specifications Simplifies component choice in noise sensitive applications Wide range of package options: PDIP, JEDEC SOIC, Applicable as upgrade to older technologies and for your most EIAJ SOIC, TSSOP advanced designs
VHC vs HC Specifications
VHC HC VHC HC
Unit VCC
DC Spec
IOH/IOL −8/8 −4/4 −8/8 −6/6 m A 4.5V ICC 20.0 20.0 40.0 µA 5.5V VOLP/VOLV 0.8/−0.8 not spec’d 0.8/−0.8 not spec’d 5.0V VILD/VIHD 1.5/3.5 not spec’d 1.5/3.5 not spec’d 5.0V
AC Spec (TA −40°C to +85°C)
t PHL,PLH 8.5 8.5 ns 5.0 ± 0.5V
t PZH, PZL 10.5 ns 5.0 ± 0.5V t PHZ,PLZ 10.5 ns 5.0 ± 0.5V
CPD (TA = 20°C) p F
© 1999 Fairchild Semiconductor Corporation MS500119.prf www.fairchildsemi.com
Page Summary Contents For Fairchild VHC VHCT Introduction and Data Handbook
Manual Details
| Brand | Fairchild |
|---|---|
| Pages | 1 |
| File Size | 10.26 KB |
| Published | June 22, 2026 |
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Frequently Asked Questions
Can VHC drive 3.3V logic from a 5V source?
Yes, the feature is beneficial for applications where 5V logic is driving 3.3V logic.
What is the maximum over-voltage input tolerance for the device?
The inputs are over-voltage tolerant to 7.0V, regardless of the supply voltage (V).
How much faster and how powerful is VHC compared to HCMOS?
VHC provides nearly three times the speed and has two times the output current drive of comparable HCMOS parts.
Can VHC be used in noisy environments or with TTL systems?
Yes, guaranteed noise specifications allow it to interface directly with older TTL parts and sub-systems.