RC5060 Ver la hoja de datos (PDF) - Fairchild Semiconductor
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RC5060 Datasheet PDF : 15 Pages
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RC5060
PRODUCT SPECIFICATION
Application Information
The RC5060 Controller
The RC5060 is a fully compliant ACPI controller IC. Used
with an ATX power supply, it generates a 5V Dual voltage, a
3.3V Dual for PCI, and power for both SDRAM and RAM-
BUS, and has a large array of additional protection functions
integrated in. Used in conjunction with Fairchild’s RC5058,
it provides the complete set of control and power functions
necessary to implement a Camino or Whitney motherboard.
It can also be used to generate the dual voltages necessary for
a Tehama motherboard.
Overview of ACPI
The Advanced Configuration and Power Interface, or ACPI,
is a system for controlling the use of power in a computer. It
enables the computer manufacturer and the computer user to
determine the computer’s power usage dynamically. For
example, when the computer has been unused for a certain
time, the monitor and peripherals could be turned off, and
their states saved to memory. After a longer period, the
processor could be turned off, and the memory saved to disk.
A peripheral could then re-awaken the entire system on the
occurrence of an event, such as the arrival of a FAX on a
modem.
As shown in Figure 6, the available power inputs to the com-
puter system from the ATX power supply are +5V main, +12V
main, +3.3V main, and +5V standby. “Main” means that
these power outputs are available under full-power operation
of the system, but can be turned off in some of the power-
saving modes. “Standby” means that this power output is
always present.
The most general ACPI system requires four dual outputs:
5V dual, 3.3V dual, 3.3V SDRAM, and 2.5V RAMBUS (or
2.5V dual). “Dual” means that the power can be (but is not
necessarily) present whether the main power supplies are
present or not. To ensure the presence of these outputs, while
not overloading the standby power, they have dual inputs,
from both main power and standby. The presence or absence
of the dual outputs is determined by the control signals to the
RC5060.
ACPI States
As shown in Table 1, there are three ACPI states that are of
primary concern to the system designer, designated S0, S3
and S5. S0 is the full-power state, the state of the computer
when it is being actively used. The other two states are sleep
states, reflecting differing levels of power-down.
S3 is a state in which the processor is powered down, but its
last state is being preserved in IC memory, which is kept on.
Since memory is fast, the computer can quickly come back
up to full operation. However, this state continues to draw
moderate power, due to the memory being kept alive.
S5 is a state in which memory is off, and the last state of the
processor has been written to the hard disk. Since the disk is
slow, the computer takes longer to come back to full operation.
However, since memory is off, this state draws minimal
power.
It is anticipated that only the following state transitions will
occur: S0 → S3, S0 → S5, S3 → S5, S5 → S0, and S3 → S0;
the transition S5 → S3 will occur only as an intermediate state
during the transition from S5 → S0. To prevent overcurrent
limit from activating, the RC5060 blocks this transition. For
example, when PWROK = SLP_S3# = 0, and SLP_S5# tran-
sitions from 0 to 1, the RC5060 remains in the S5 state. See
Table 2.
5V Dual Output
The RC5060 controls four separate dual outputs, the first of
which is the 5V dual. This output is intended to run sub-
systems such as the USB ports. A typical application that
would require the use of 5V dual rather than +5V main for a
USB port would be the use of a USB mouse: if the system
needs to be able to awaken from sleep when the mouse is
moved, then the mouse must be powered from dual, because
main power is off.
5V dual is generated by two MOSFET switches, one from
+5V main, the other from +5V standby, as shown in Figures
4 or 5. When main power is present, the first switch is on and
the second off, and the opposite when main power is absent.
Note carefully the polarity of the MOSFET Q5 that delivers
power from the +5V main to the 5V dual: opposite to the
connection of Q6, the source is connected to the +5V main
input, and the drain is connected to the 5V dual output. This
connection must be done this way because of Q5’s body
diode. When +5V main is not present, 5V dual is still on, and
if Q5 were connected with the same polarity as Q6, the dual
voltage would conduct through the body diode of Q5,
attempting to power up the entire +5V main line. It is to
avoid this overload that Q5 must be connected as shown.
The state of the switches is controlled by the SLP_ S3# and
PWROK lines, as shown in Figure 3. When both SLP_ S3#
and PWROK are asserted, the main switch is on, and the
standby switch is off. If either line is de-asserted, the main
switch is off and the standby switch is on.
Note that Q5 and Q6 should be low-gate-voltage type
MOSFETs, with guaranteed operation at 2.7V Vgs, in order
to ensure full enhancement in worst case. In a typical system,
it is anticipated that full-power current will be about 1A maxi-
mum, and standby current will be about 200mA maximum.
3.3V Dual Output
The 3.3V dual output is intended to power subsystems such
as the computer’s PCI slots. A typical application that would
require the use of 3.3V dual rather than +3.3V main for a PCI
slot would be the use of a modem: if the system needs to be
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REV. 1.0.2 9/14/01
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