MAX8586ETA/V+T Maxim Integrated Products, MAX8586ETA/V+T Datasheet - Page 8

• Manufacturer Part Number: MAX8586ETA/V+T
• Description: IC USB SWITCH 1.2A SGL 8-TDFN
• Manufacturer: Maxim Integrated Products
• Type: USB Switchr

Specifications of MAX8586ETA/V+T

• Number Of Outputs: 1
• Rds (on): 55 mOhm
• Internal Switch(s): Yes
• Current Limit: 1.2A
• Voltage - Input: 2.75 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX8586 uses two methods to protect the circuit
from overcurrent conditions. Continuous current limiting
has tighter accuracy but slower response time com-
pared to short-circuit limiting. Combining both methods
provides a high degree of protection for a variety of
faults. When a current-limit fault occurs with V
greater than 1V, the device operates in continuous cur-
rent-limit mode and limits output current to a user-pro-
grammable level. When V
device operates in short-circuit current-limit mode and
pulses the output current to levels that are 30% (typ)
higher than the selected continuous current limit.
When either fault condition persists for 20ms (typ), the
fault flag is asserted. With the auto-restart enabled
(ENRESET high) the output also latches off and is test-
ed with a 25mA current to detect when the fault condi-
tion has been removed. 20ms after the fault condition is
removed, the output automatically restarts. With the
auto-restart disabled (ENRESET low), the output contin-
ues to source the current-limit current as long as the
fault is present.
The USB specification does not allow an output device
to source current back into the USB port. However, the
MAX8586 is designed to safely power noncompliant
devices. During normal operation with the channel
enabled, if the current from the output to the input
exceeds 1A (typ) for more than 20ms (typ), the IC turns
off the switch and the FAULT flag is asserted. When the
IC is disabled, the output is switched to a high-imped-
ance state, blocking reverse current flow from the out-
put back to the input.
The MAX8586 has a selectable active-high/low ON
polarity. Drive SEL high to select an active-high for ON;
drive SEL low to select active-low for ON. The
MAX8586 includes a UVLO circuit to prevent erroneous
switch operation when the input voltage goes low dur-
ing startup and brownout conditions. Input voltages of
less than +2.5V (typ) inhibit operation of the device.
FAULT asserts low during a UVLO condition.
The MAX8586 uses an auto-restart function to detect
short-circuit removal by sourcing 25mA from the output
and monitoring the output voltage. When the voltage at
Single 1.2A USB Switch in
3mm x 3mm TDFN
8
Output Fault Protection and Auto-Restart
_______________________________________________________________________________________
Reverse Current Protection
Detailed Description
On/Off Control and UVLO
Current-Limit Protection
OUT
is less than 1V, the
OUT
the output exceeds 0.5V for 20ms, the fault flag releases,
the output turns back on, and the 25mA current source
turns off. Active loads are not expected to draw measur-
able current when supplied with less than 0.5V. The auto-
restart function is enabled when ENRESET is high. Drive
ENRESET low to disable the auto-restart function. When
the auto-restart function is disabled, OUT regulates the
current to the programmed current limit.
The MAX8586 provides an open-drain output (FAULT)
to signal fault conditions. Connect FAULT to IN through
a 100kΩ pullup resistor for most applications. FAULT
asserts low when any of the following conditions occur:
•
•
•
•
When auto-restart is enabled, the FAULT output goes
high impedance after a 20ms delay once the fault con-
dition is removed. With auto-restart disabled, during the
fault the output is tested every 20ms. When the fault is
removed, the FAULT output goes high impedance after
a delay that can be up to 20ms. Ensure that the
MAX8586 input bypass capacitance prevents glitches
from triggering the FAULT output. To distinguish large
capacitive loads from short circuits or sustained over-
loads, the MAX8586 has a fault-blanking circuit. When
a load transient causes the output to enter current limit,
an internal counter monitors the duration of the fault.
For load faults exceeding the 20ms fault-blanking time,
the switch turns off, FAULT asserts low, and the output
enters auto-restart mode (see the Current-Limit
Protection and Output Fault Protection and Auto-Restart
sections). Only current-limit and short-circuit faults are
blanked. Thermal-overload faults and input voltages
below the UVLO threshold immediately turn the output
off and assert FAULT low.
Fault blanking allows the MAX8586 to handle USB
loads that might not be fully compliant with USB specifi-
cations. The MAX8586 successfully powers USB loads
with additional bypass capacitance and/or large start-
up currents while protecting the upstream power
source. No fault is reported if the switch brings up the
load within the 20ms blanking period.
The input voltage is below the UVLO threshold.
The switch junction temperature exceeds the
+160°C thermal-shutdown temperature limit.
The switch is in current-limit or short-circuit current-
limit mode for longer than the fault-blanking period
(20ms typ).
The reverse current exceeds the 1A threshold for
longer than the fault-blanking period (20ms typ).
Fault Indicator and Fault Blanking