Rainbow Electronics AT88SC018 - Manual (Page 3)

CryptoCompanion
™ Chip
3
5277CS–CryptoCompanion–2/09
1.3. Package, Pin Definition & IO
1.3.1. Pin Definition
1.3.1.1. V
CC
, Gnd
Power supply is 2.7 – 3.6V. Supply current less than 5 mA.
CryptoCompanion will be available to accept commands 60 ms after the later of V
CC
rising above 2.7V or Reset being
driven high if CryptoCompanion is in a security delay then this interval is significantly longer.
During Power Up, V
CC
must exhibit a monotonic ramp at a minimum rate of 50 mV/mS until V
CC
has crossed the 2.7V
level. During Power Down, V
CC
must exhibit a monotonic ramp at a minimum rate of 50 mV/mS once it has dropped
below the 2.5V boundary. CryptoCompanion does not support hot swapping or hot plugging.
V
CC
must be bypassed with high quality surface mount capacitors that are properly located on the board. Atmel
recommends two capacitors connected in parallel having a value of 1
μF and 0.01μF. The capacitors should be
manufactured using X5R or X7R dielectric material. These capacitors should be connected to CryptoCompanion using
a total of no more than 1cm PC board traces. Atmel recommends the use of a ground plane and a trace length of less
than 0.5cm between the capacitors and the V
CC
pin. Failure to follow these recommendations may result in improper
operation.
1.3.1.2. SDA
Two wire interface data pin, 5 V compatible. Minimum data setup time = 0.1
μs, and minimum data hold time = 0 μs min.
The system board must include an external pull-up resistor.
1.3.1.3. SCL
Two wire interface clock pin, 5 V compatible. Maximum SCL rate is 400KHz, minimum T
LOW
= 1.2
μs, minimum
T
HIGH
= 0.6
μs. The system board must include an external pull-up resistor.
1.3.1.4. Reset (RST)
This active low input will reset all states within CryptoCompanion. Honored regardless of the state of PowerDown.
1.3.1.5. PowerDown (PDN)
When held low, the part operates normally. When held high the part will go to sleep and ignore all transitions on SDA
and SCL, power consumption will drop to less than 10
μA. There is a 50 ms delay between this pin falling and the first
transition on SDA or SCL that will be accepted by the chip.