74HC191DB: Presettable synchronous 4-bit binary up/down counter
The 74HC/HCT191 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A.
The 74HC/HCT191 are asynchronously presettable 4-bit binary up/down counters. They contain four master/slave flip-flops with internal gating and steering logic to provide asynchronous preset and synchronous count-up and count-down operation.
Asynchronous parallel load capability permits the counter to be preset to any desired number. Information present on the parallel data inputs (D0 to D3) is loaded into the counter and appears on the outputs when the parallel load (PL) input is LOW. As indicated in the function table, this operation overrides the counting function.
Counting is inhibited by a HIGH level on the count enable (CE) input. When CE is LOW internal state changes are initiated synchronously by the LOW-to-HIGH transition of the clock input. The up/down (U/D) input signal determines the direction of counting as indicated in the function table. The CE input may go LOW when the clock is in either state, however, the LOW-to-HIGH CE transition must occur only when the clock is HIGH. Also, the U/D input should be changed only when either CE or CP is HIGH.
Overflow/underflow indications are provided by two types of outputs, the terminal count (TC) and ripple clock (RC). The TC output is normally LOW and goes HIGH when a circuit reaches zero in the count-down mode or reaches '15' in the count-up-mode. The TC output will remain HIGH until a state change occurs, either by counting or presetting, or until U/D is changed. Do not use the TC output as a clock signal because it is subject to decoding spikes. The TC signal is used internally to enable the RC output. When TC is HIGH and CE is LOW, the RC output follows the clock pulse (CP). This feature simplifies the design of multistage counters.
Outline 3d SOT338-1
Data Sheets (1)
Application Notes (2)
Users Guides (1)
| Name/Description | Modified Date |
|---|
| HC/T User Guide (REV 1.0) PDF (508.0 kB) HCT_USER_GUIDE [English] | 01 Nov 1997 |
Package Information (1)
Supporting Information (2)
Ordering Information
| Product | Status | Family | Function | VCC (V) | Description | Output drive capability (mA) | Package version | Logic switching levels | tpd (ns) | Power dissipation considerations | Tamb (Cel) | Rth(j-a) (K/W) | Ψth(j-top) (K/W) | Rth(j-c) (K/W) | Package name | No of pins |
|---|
| 74HC191DB | Active | HC(T) | Binary counters/timers | 2.0 - 6.0 | presettable synchronous 4-bit binary up/down counter | +/- 5.2 | SOT338-1 | CMOS | 22 | low | -40~125 | 148 | 42.0 | | SSOP16 | 16 |
Package Information
| Product ID | Package Description | Outline Version | Reflow/Wave Soldering | Packing | Product Status | Part NumberOrdering code(12NC) | Marking | Chemical Content | RoHS / Pb Free / RHF | LeadFree Conversion Date | EFR | IFR(FIT) | MTBF(hour) | MSL | MSL LF |
|---|
| 74HC191DB | | SOT338-1 | SSOP-TSSOP-VSO-REFLOW
SSOP-TSSOP-VSO-WAVE
SSOP-TSSOP-VSO-REFLOW
SSOP-TSSOP-VSO-WAVE | Reel 13" Q1/T1 | Active | 74HC191DB,118
(9351 886 00118) | HC191 | 74HC191DB |    | week 12, 2005 | 84.9 | 6.62 | 1.51E8 | 1 | 1 |
| Bulk Pack | Active | 74HC191DB,112
(9351 886 00112) | HC191 | 74HC191DB | | week 12, 2005 | 84.9 | 6.62 | 1.51E8 | 1 | 1 |
