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 seperate, 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.
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.
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