Features
• Synchronous or Asynchronous Preset
• Cascadable in Synchronous or Ripple Mode
• Fanout (Over Temperature Range)
- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads
- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads
• Wide Operating Temperature Range . . . -55oC to 125oC
• Balanced Propagation Delay and Transition Times
• Significant Power Reduction Compared to LSTTL
Logic ICs
• HC Types
- 2V to 6V Operation
- High Noise Immunity: NIL = 30%, NIH = 30% of VCC
at VCC = 5V
• HCT Types
- 4.5V to 5.5V Operation
- Direct LSTTL Input Logic Compatibility,
VIL= 0.8V (Max), VIH = 2V (Min)
- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

Description
The ’HC40103 and CD74HCT40103 are manufactured with
high speed silicon gate technology and consist of an 8-stage
synchronous down counter with a single output which is
active when the internal count is zero. The 40103 contains a
single 8-bit binary counter. Each has control inputs for
enabling or disabling the clock, for clearing the counter to its
maximum count, and for presetting the counter either
synchronously or asynchronously. All control inputs and the
TC output are active-low logic.
In normal operation, the counter is decremented by one
count on each positive transition of the CLOCK (CP).
Counting is inhibited when the TE input is high. The TC
output goes low when the count reaches zero if the TE input
is low, and remains low for one full clock period.
When the PE input is low, data at the P0-P7 inputs are
clocked into the counter on the next positive clock transition
regardless of the state of the TE input. When the PL input is
low, data at the P0-P7 inputs are asynchronously forced into
the counter regardless of the state of the PE, TE, or CLOCK
inputs. Input P0-P7 represent a single 8-bit binary word for
the 40103. When the MR input is low, the counter is
asynchronously cleared to its maximum count of 25510,
regardless of the state of any other input. The precedence
relationship between control inputs is indicated in the truth
table.
If all control inputs except TE are high at the time of zero
count, the counters will jump to the maximum count, giving a
counting sequence of 10016 or 25610 clock pulses long.
The 40103 may be cascaded using the TE input and the TC
output, in either a synchronous or ripple mode. These
circuits possess the low power consumption usually
associated with CMOS circuitry, yet have speeds
comparable to low power Schottky TTL circuits and can drive
up to 10 LSTTL loads.