PowerCap Package Allows for Density Upgrades, Surface Mount Assembly
May 30, 2002
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.
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.
