ISL6185 Datasheet, PDF (9/20 Pages) Intersil Corporation – Dual USB Port Power Supply Controller

ISL6185
Introduction
The ISL6185 is a dual channel fully independent
overcurrent (OC) fault protection IC for the +2.5V to +5V
environment. Each ISL6185 incorporates in a single
package two 85mΩ P-channel MOSFET power switches
for power control. Independent enabling inputs and fault
reporting outputs compatible with 2.5V to 5V logic allows
for external control and reporting. This device features
integrated power switches with current monitoring,
accurate current limiting, reverse bias protection and
current limited timed delay to turn-off for system
reliability. See Figures 11 through 26 for typical
operational waveforms including both under and
overcurrent situations.
The ISL6185 offers current sense and limiting with
V_IN = 5V guaranteed continuous current product
variants of 0.6A, 1.1A, 1.5A and 1.8A making these
devices well suited for a myriad of USB and other low
power (9W max) port power management applications
and configurations.
The ISL6185 also provides a thermally insensitive timed
OC turn-off and fault notification, isolating and protecting
the voltage bus in the event of a peripheral OC event or
short circuit event independent of the adjoining switch’s
electrical or the ambient thermal condition.
The ISL6185 undervoltage lockout feature prevents
turn-on of the outputs unless the correct ENABLE
state and V_IN > V_UVLO are present. During initial
turn-on the ISL6185 prevents fault reporting by
blanking the fault signal.
During operation, once an OC condition is detected
the output is current limited for t_CL to allow transient
OC conditions to pass. If still in current limit after the
current limit period has elapsed, the output is then
turned off and the fault is reported by pulling the
corresponding FAULT output low. On the latch off
options, after turn-off both the output and the FAULT
signal are latched low until reset by the enable signal
being de-asserted or a POR occurs at which time the
FAULT signal will clear and the switch is ready to be
turned back on. On the auto restart options the
ISL6185 will attempt to periodically turn-on the
output as long as the enable is asserted.
When disabled the ISL6185 has a low quiescent supply
current and output to input reverse current flow blocking
capability.
The ISL6185 family is provided with enable polarity
options and an industry standard 8 lead SOIC pinout
along with two versions in the 70% smaller 3x3 DFN. The
8 Ld DFN package offers the same performance as the
8 Ld SOIC whereas the 10 Ld DFN offers higher current
capability in the smallest possible package because of
lower package electrical and thermal resistance.
Functional Description
Power On Preset (POR)
The ISL6185 POR feature inhibits device functionality
when VIN <V_UVLO.
Reverse Polarity Protection
In any event where the power switch is disabled and
V_OUT > V_IN there will be no output to input current flow
nor will the output voltage appear on the input.
Soft-Start
Upon enable, the switch passes a constant current to
the load. The voltage on the VOUT pin will ramp up
according the equation: I_LIM/C_OUT (V/s). Resistive or
active load will slow the V_OUT ramp up toward the top
of its curve.
Fault Blanking On Start-Up
During initial turn-on, the ISL6185 prevents nuisance
faults being reported to the system controller by blanking
the fault signal until the internal FET is fully enhanced.
Current Trip and Limiting Levels
The ISL6185 provides integrated current sensing in the
MOSFET that allows for rapid control of OC events. Once
an OC condition is detected the ISL6185 goes into its
current limiting (CL) control mode. The ISL6185 is
variant specified to allow a continuous current (I_CONT)
operation of 0.6A, 1.1A, 1.5A or 1.8A. As the current
increases past its continuous current rating it will reach a
level that causes the device to enter its current limit
mode, that is the current trip level. The current trip level
is in all cases adequately above the I_CONT rating as to
not cause unintended false faults. The current limit is
specified at V_OUT = V_IN - 1V to test a known
representative condition and is featured at a nominal
value slightly higher than the continuous current rating.
The speed of this current limiting control is inversely
related to the magnitude of the OC fault. Thus a hard
overcurrent is more quickly pulled to its limiting value
than a marginal OC condition.
Over-Temperature Shutdown
Although the ISL6185 has an over-temperature
shutdown and lockout feature, because of the 12ms
timed shutdown the thermal shutdown is likely only to be
invoked in extremely high ambient temperatures.
The over- temperature protection invokes and disables
the switch turn-on operation once the die temperature is
~+140°C, it will turn off an already on switch at
~+150°C and releases the part to operation once the die
temperature falls to ~+120°C.
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FN6937.0
October 22, 2010