1.1

Cold spare

The 54VCXH163245 features a cold spare input and output buffer. In high reliability applications, cold sparing

enables a redundant device to be tied to the data bus with its power supply at 0 V (VCC = 0 V) without

affecting the bus signals or injecting current from the I/Os to the power supplies. Cold sparing also allows

redundant devices that are not powered to be switched on when required only. Power consumption is therefore

reduced by switching off the redundant circuit. This has no impact on the application. Cold sparing is achieved

by implementing a high impedance between I/Os and VCC. The ESD protection is ensured through a non-

conventional dedicated structure. Using cold spare on Bus A and Bus B separately is not allowed. In cold spare,

both VCCA and VCCB must be at 0 V.

Figure 2. Cold spare and cold redundancy

Powered-on Device

Powered-off Device

(cold-spare)

+Vcc

0V (GND)

mAn

mBn

mAn

mBn

Ioff

Ioff

Cin

10pF

Cout

Cout

12pF

R (1)

R (1)

1.

R = Ioff/VCC

54VCXH163245

Cold spare

DS11681 - Rev 7

page 3/19