P8237A Multimode DMA Controller 5V 65mA DIP-40
P8237A (also known as Am9517A) is a high-performance Multimode Direct Memory Access (DMA) Controller designed to enhance system throughput by allowing peripherals to transfer data directly to and from system memory without CPU intervention. It features four independent DMA channels, each with full 16-bit address and word count capability. The controller supports multiple transfer modes—including block, demand, single, and cascade—and can be cascaded to expand the number of channels. It also supports memory-to-memory transfers, autoinitialization, and programmable priority schemes. Its operation is controlled via an external clock and a set of programmable registers, making it a flexible solution for high-speed data movement in embedded and computing systems.
Features:
- Four independent DMA channels with individual mode control.
- Supports multiple transfer modes: Block, Demand, Single, and Cascade.
- Memory-to-memory and memory block initialization capabilities.
- Autoinitialization of channels after transfer completion.
- Programmable address increment/decrement.
- Expandable to any number of channels by cascading.
- Software-programmable DMA requests.
- Configurable polarity for DREQ and DACK signals.
- Compressed timing option for higher transfer rates (up to 2.5 MB/s).
- Compatible with standard +5V systems.
- Available in 40-pin DIP and 44-pin PLCC packages.
Specifications:
| Parameter | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Supply Voltage: | VCC | 4.75 | 5.0 | 5.25 | V |
| Clock Frequency (P8237A-5): | fCLK | – | 5.0 | – | MHz |
| Operating Temperature (Commercial): | TA | 0 | – | 70 | °C |
| Quiescent Supply Current: | ICC | – | 65 | 130 | mA |
| Input High Voltage: | VIH | 2.0 | – | VCC+0.5 | V |
| Input Low Voltage: | VIL | -0.5 | – | 0.8 | V |
| Output High Voltage: | VOH | 2.4 | – | – | V |
| Output Low Voltage: | VOL | – | – | 0.4 | V |
| Power Dissipation: | PD | – | – | 1.5 | W |
Pinout:
| Pin | Name | I/O | Description |
|---|---|---|---|
| 1 | IOR | I/O | I/O Read |
| 2 | IOW | I/O | I/O Write |
| 3 | MEMR | O | Memory Read |
| 4 | MEMW | O | Memory Write |
| 5 | (NC) | – | Reserved (tie high) |
| 6 | READY | I | Ready Input |
| 7 | HLDA | I | Hold Acknowledge |
| 8 | ADSTB | O | Address Strobe |
| 9 | AEN | O | Address Enable |
| 10 | HRQ | O | Hold Request |
| 11 | CS | I | Chip Select |
| 12 | CLK | I | Clock Input |
| 13 | RESET | I | Reset |
| 14–15, 24–25 | DACK0–3 | O | DMA Acknowledge Outputs |
| 16–19 | DREQ0–3 | I | DMA Request Inputs |
| 20 | VSS | – | Ground |
| 21–23, 26–30 | DB0–7 | I/O | Data Bus |
| 31 | VCC | – | +5V Supply |
| 32–35 | A0–3 | I/O | Address Bits 0–3 |
| 36 | EOP | I/O | End of Process |
| 37–40 | A4–7 | O | Address Bits 4–7 |
Footprint:
Applications:
- High-speed data acquisition systems.
- Disk and tape controller interfaces.
- Memory-to-memory block moves.
- Graphics and display refresh.
- Communication buffer management.
- Industrial automation and control.
Packages:
- 1x P8237A Multimode DMA Controller 5V 65mA DIP-40.
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