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HEF4521B MSI
General description
The HEF4521B consists of a chain of 24 toggle flip-flops with an overriding asynchronous master reset input (MR), and an input circuit that allows three modes of operation. The single inverting stage (I2 /O2 ) will function as a crystal oscillator, or in combination with I1 as an RC oscillator, or as an input buffer for an external oscillator. Low-power operation as a crystal oscillator is enabled by connecting external resistors to pins 3 (VSS ?) and 5 (VDD ?).
Each flip-flop divides the frequency of the previous flip-flop by two, consequently the HEF4521B will count up to 224 = 16777216. The counting advances on the HIGH to LOW transition of the clock (I2 ). The outputs of the last seven stages are available for additional flexibility.
Products/packages
| Type number | North American Type number | Ordering code (12NC) | Product status | Package | Packing | Marking | Chemical content | Leadfree conversion date |
|---|---|---|---|---|---|---|---|---|
| HEF4521BP | HEF4521BPN | 9334 067 50652 | Volume production | SOT38-4
(DIP16) | Bulk Pack, CECC | Standard Marking | HEF4521BP
| Always Pb-free |
| HEF4521BT | HEF4521BTD | 9334 067 70652 | Volume production | SOT109-1
(SO16) | Bulk Pack, CECC | Standard Marking | HEF4521BT
| week 4, 2004 |
| HEF4521BT | HEF4521BTD-T | 9334 067 70653 | Volume production | SOT109-1
(SO16) | Reel Pack, SMD, 13", CECC | Standard Marking | HEF4521BT
| week 4, 2004 |
Pricing/ordering/availability
| Type number | Ordering code(12NC) | Indicative price/unit($) | Region | Distributor | In stock | Order quantity | Inventory date | Buy online | Samples |
|---|---|---|---|---|---|---|---|---|---|
| HEF4521BP | 9334 067 50652 | 0.4800 | NA | ARROW ELECTRONICS | 1,000 | 1/6/2009 | Buy online | Order samples | |
| HEF4521BT | 9334 067 70652 | 0.4500 | NA | AVNET ELECTRONICS MARKETING | 500 | 1/7/2009 | Buy online | not available | |
| NA | DIGI-KEY CORPORATION | 3,269 | 1/6/2009 | Buy online | |||||
| HEF4521BT | 9334 067 70653 | 0.4500 | NA | MOUSER ELECTRONICS | 2,430 | 1/7/2009 | Buy online | not available |
Parametrics/similar products
| Type number | Package | Description | Propagation Delay(ns) | Voltage | No. of Pins | Power Dissipation Considerations | Logic Switching Levels | Output Drive Capability |
|---|---|---|---|---|---|---|---|---|
| HEF4521BP | SOT38-4
(DIP16) | 24-Stage Frequency Divider and Oscillator | 220@15V | 4.5-15.5 V | 16 | Low Power or Automotive Applications | CMOS | +/- 2.4 mA @ 15 V |
| HEF4521BT | SOT109-1
(SO16) | 24-Stage Frequency Divider and Oscillator | 220@15V | 4.5-15.5 V | 16 | Low Power or Automotive Applications | CMOS | +/- 2.4 mA @ 15 V |
Similar products
HEF4521B MSI
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