Dual Decade Counter

The TC74AC390 is an advanced high speed CMOS DUAL DECADE COUNTER fabricated with silicon gate and double-layer metal wiring C2MOS technology.

It achieves the high speed operation similar to equivalent Bipolar Schottky TTL while maintaining the CMOS low power dissipation.

It consists of two independent 4-bit counters, each composed of a divide-by-two and a divide-by-five counter. The divide-by-two counter is incremented on the negative going transition of clock A ( CKA ). The divided-by-five counter is incremented on the negative going transition of clock B ( CKB ). The counter can be cascaded to form decade, bi-quinary, or various combinations up to a divide-by-100 counter. When the CLEAR input is set high, the Q outputs are set to low independent of the clock inputs.

All inputs are equipped with protection circuits against static discharge or transient excess voltage.

Features

• High speed: fmax = 160 MHz (typ.) at VCC = 5 V

• Low power dissipation: ICC = 8 μA (max) at Ta = 25°C

• High noise immunity: VNIH = VNIL = 28 VCC (min)

• Symmetrical output impedance: |IOH| = IOL = 24 mA (min)

Capability of driving 50 Ω

transmission lines.

• Balanced propagation delays: tpLH ∼ − tpHL

• Wide operating voltage range: VCC (opr) = 2 to 5.5 V

• Pin and function compatible with 74HC390