MIC2569 Datasheet, PDF (11/16 Pages) Micrel Semiconductor – CableCARD™ Power Switch

Micrel, Inc.
Functional Description
3.3VIN and 5.0VIN
3.3VIN and 5VIN are the input power supplies for
the MIC2569. 3.3VIN powers the MIC2569’s
internal functions; as well as, VCC, and VPP1 and
VPP2. 5VIN provides power to VPP1 and VPP2.
Tables 1 and 2 shows the control states which
supply is provided to which output
C0, C1, C2 (States Controls)
C0, C1, and C2 control the output conditions for
VCC, VPP1 and VPP2. C0, C1, and C2 are inputs
to the MIC2569 provided by the host. See Tables 1
and 2 for a complete listing. Also see the
Application Information section.
VCC
VCC provides the main 3.3V supply to the
CableCARD device. VCC is protected against high
current conditions and short circuits. The minimum
current limit is set to 1.3A from 3.3VIN. Break-
before-make switching prevents crossed
connections during state changes. The VCC output
depends on the host / card combination. See
Tables 1 and 2 for a complete listing. Also see the
Application Information section.
VPP1, VPP2 (VPP1/2)
VPP1 and VPP2 provide the 3.3V and 5.0V supplies
to the CableCARD device. VPP1 and VPP2 are
protected against high current conditions and short
circuits. The minimum current limit is set to a
minimum of 150mA. Note: VPP1 and VPP2 are
powered separately with each having a current limit
of 150mA Break-before-make switching prevents
crossed connections during state changes. The
VPP1/2 output depends on the host / card
combination. See Tables 1 and 2 for a complete
listing. Also see the Application Information section.
Soft-Start
The VCC, VPP1 and VPP2 outputs are all slew rate
MIC2569
controlled insuring a soft-start turn-on characteristic.
Soft-starting is in effect anytime a supply ramps from a
0V condition or switches between voltages, as in the
case of the VPP outputs.
Thermal Shutdown
Because electrical faults can cause significant heating in
power switches, MIC2569 monitors its internal
temperature and will shut down should the die
temperature reach 140°C. When the die temperature
has dropped by about 10 degrees, MIC2569 will
reactivate its outputs. If there is still a problem, the
effected power switch will again get hot, shutting off all
outputs. This power cycling action will continue as long
as the fault persists. Once removed, MIC2569 will
resume normal operation.
FAULT/
FAULT/ is a LOW true open drain output which signals
an over current or over-temp condition. As an open drain
device, this output can be wire OR’d with other FAULT/
outputs to a single input pin on the host. For proper
operation this output must be pulled-up to the logic
supply rail by an external resistor. This resistor can be
large in value, but not so large that leakage currents
caused by surface contamination can cause a false
indication of a fault condition. For this reason it is
recommended that the pull-up resistor be 300kΩ or less.
FAULT/ is delayed with respect to an over current
condition being detected. This is to prevent brief current
spikes from triggering an interrupt to the system host.
The delay is on the order of 12ms. Any fault lasting over
8 ms triggers the FAULT/ output. There is no delay for
thermal faults. Any over-temp condition is reported
immediately.
UVLO (Under Voltage Lockout)
An under-voltage lock out (UVLO) circuit monitors the
3.3VIN rail and keeps MIC2569 disabled until the input
voltage reaches the minimum level needed for proper
operation. Below this voltage the output switches are
OFF and all functionality is disabled.
September 2007
11
M9999-092507-C
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