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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 | Inventory date | Buy online | Samples |
|---|---|---|---|---|---|---|---|---|
| HEF4521BP | 9334 067 50652 | 0.4800 | NA | ARROW ELECTRONICS | 1,000 | 7/4/2008 | Buy online | Order samples |
| NA | FUTURE ELECTRONICS | 561 | 7/4/2008 | Buy online | ||||
| HEF4521BT | 9334 067 70652 | 0.4500 | NA | DIGI-KEY CORPORATION | 578 | 6/29/2008 | Buy online | not available |
| HEF4521BT | 9334 067 70653 | 0.4500 | NA | MOUSER ELECTRONICS | 2,465 | 7/5/2008 | 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 links to the similar products page containing an overview of products that are similar in function or related to the type number(s) as listed on this page. The similar products page includes products from the same catalog tree(s), relevant selection guides and products from the same functional category.
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