Datasheet
Hot-Swap SCSI Backplane 1U Server Chassis SR1300
Revision 1.2
Intel order number A94544-004
30
6.3.2 Phillips* P80C652EBB Micro-Controller
The SCSI backplane supports the SAF-TE 1.0 specification and utilizes the Philips*
P80C652EBB micro-controller for all SAF-TE functions. If necessary, the backplane can
function without the SAF-TE micro-controller as a simple interconnection for the SCSI drives
and termination in LVD or single-ended (SE) mode.
P80C652XEBB features:
• Operating frequency is 12 MHz
• 80C51-based architecture
• Four 8-bit I/O ports
• Two 16-bit timer/counters
• Full-duplex Universal Asynchronous Receiver Transmitter (UART) facilities
• I
2
C serial interface
• Two power control modes - idle mode and power-down mode
• Operating temperature range: 0°C to +70°C
6.3.2.1 I
2
C Serial Communication-SI01
The I
2
C pins are alternate functions to port pins P1.6 and P1.7. Because of this, P1.6 and P1.7,
on these parts, do not have a pull-up structure as found of the 80C51. Therefore P1.6 and P1.7
have open drain outputs on the 80C652.
6.3.2.2 I
2
C Electrical Input/Output Specifications
The I
2
C bus allows communication between devices made in different technologies, which might
also use different supply voltages.
For devices with fixed input levels, operating on a supply voltage of +5V ±10%, the following
levels have been defined:
• V
ILmax
= 1.5 V (maximum input low voltage)
• V
IHmin
= 3 V (minimum input high voltage)
Devices operating on a fixed supply voltage different from +5 V (e.g., I
2
L), must also have these
input levels of 1.5 V and 3 V for V
IL
and V
IH
, respectively.
For devices operating over a wide rage of supply voltages (e.g.,Complementary Metal Oxide
Silicon {CMOS}), the following levels have been defined:
• V
ILmax
= 0.3 V
DD
(maximum input Low voltage)
• V
IHmin
= 0.7 V
DD
(minimum input High voltage)
For both groups of devices, the maximum output low value has been defined:
• V
OLmax
= 0.4 V (max. output voltage Low) at 3mA sink current
The maximum low-level input current at V
Olmax
, of both the SDA pin and the SCL pin of an I
2
C
device is, -10uA, including the leakage current of a possible output stage.