PowerCap Package Allows for Density Upgrades, Surface Mount Assembly

Abstract: This application note provides an overview of the PowerCap product line. The PowerCap products allows surface-mounting of the component base, while keeping the temperature sensitive crystal and/or battery in a separate, snap-on assembly.

Memory Densities from 8k x 8 through 512k x 8 in the Same Footprint

The PowerCap package provides for an easy memory density upgrade without having to change the PCB hardware layout. When designing this package into a system, the higher order address signals should be connected to the package so that a higher density NV RAM can be added to the system without hardware modifications. All three family types have power, ground, address, data, and control signals on the same pins. Depending on the family type, pins 1, 4, 33, and 34 have other functions associated with them.

Figure 1. Powercap and module base generic diagram.
Figure 1. Powercap and module base generic diagram.

Table 1. Part numbers by family and density
Phantom Clocks Watchdog Clocks Bytewide Clocks Bytewide NV SRAM NV SRAM Density (Bytes) Addresses Required
DS1386-8 DS1643 8k A12-A0
DS1553 DS1743 8k A12-A0
DS1244 DS1386-32 DS1644 DS1230 32k A14-A0
DS1544 DS1744 DS1330 32k A14-A0
DS1248 DS1486 DS1646 DS1245 128k A16-A0
DS1556 DS1746 DS1345 128k A16-A0
DS1251 DS1647 DS1250 512k A18-A0
DS1557 DS1747 DS1350 512k A18-A0

The two-piece assembly protects the lithium battery, contained in the PowerCap (upper half) from the high temperatures of reflow soldering. The module base (lower half) is a small PCB with surface-mount leads, SRAM, and controller ICs. After the module base is surface-mounted, the PowerCap is snapped onto the base to complete the module.

The PowerCap is ordered separately from the base. The DS9034 PowerCap contains a battery for bytewide module bases. The DS9034PCX contains a battery and crystal to operate the real-time clock in the clock bases.

PowerCap Module Base
DS9034PC Bytewide NV SRAM
DS9034PCX Bytewide Clock
DS9034PCX Phantom Clock
DS9034PCX Watchdog Clock
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