MAX1564ETE+ Maxim Integrated Products, MAX1564ETE+ Datasheet - Page 8

• Manufacturer Part Number: MAX1564ETE+
• Description: IC TRIPLE USB SW 1.2A 16-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX1564ETE+

• Applications: USB
• Interface: USB
• Voltage - Supply: 2.7 V ~ 5.5 V
• Package / Case: 16-TQFN Exposed Pad
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Triple 1.2A USB Switch in 4mm x 4mm
Thin QFN
current limiting. When V
device operates in continuous current-limit mode and
limits output current to a user-programmable level.
When V
short-circuit current-limit mode and pulses the output
current to levels that are 30% (typ) higher than the
selected current limit. When either fault condition per-
sists for 20ms (typ), the output turns off and its fault flag
is asserted. The output automatically restarts 20ms
after the short or overload is removed.
The MAX1564 detects short-circuit removal by sourcing
25mA from the output and monitoring the output volt-
age. When the voltage at the output exceeds 0.5V for
20ms, the fault flag resets, the output turns back on,
and the 25mA current source turns off. Active loads are
not expected to draw measurable current when sup-
plied with less than 0.5V. The MAX1564 can also be
reset from a fault by toggling the ON_ input for the
offending channel.
The USB specification does not allow an output device
to source current back into the USB port. However, the
MAX1564 is designed to safely power noncompliant
devices. During normal operation with the channel
enabled, the IC immediately turns off the switch if the
output voltage rises above the input voltage sufficiently
to create a reverse current in excess of 0.9A (typ). If the
output voltage condition persists for longer than 20ms
(typ), the switch remains off and the FLT_ flag is assert-
ed. When any channel is disabled, the output is
switched to a high-impedance state, blocking reverse
current flow from the output back to the input.
Independent thermal shutdown of each channel per-
mits delivering power to normal loads even if one load
has a fault condition. The thermal limit does not have
the 20ms fault blanking but sets the same fault latch
that is used for other faults. Exiting this latched state is
described in the Auto-Restart Mode section.
The MAX1564 provides an independent open-drain
fault output (FLT_) for each switch. Connect FLT_ to IN_
through a 100kΩ pullup resistor for most applications.
FLT_ asserts low when any of the following conditions
occur:
• The input voltage is below the UVLO threshold.
• The switch junction temperature exceeds the +160°C
8
thermal-shutdown temperature limit.
_______________________________________________________________________________________
OUT_
Fault Indicators and Fault Blanking
is less than 1V, the device operates in
Reverse Current Blocking
OUT_
Thermal Shutdown
Auto-Restart Mode
is greater than 1V, the
• The switch is in current-limit or short-circuit current-
• The reverse current condition exists after the fault-
The FLT_ output goes high impedance after a 20ms
delay once the fault condition is removed. Ensure that
the MAX1564 input bypass capacitance prevents
glitches from triggering the FLT_ outputs. To differenti-
ate large capacitive loads from short circuits or sus-
tained overloads, the MAX1564 has an independent
fault-blanking circuit for each switch. When a load tran-
sient 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, FLT_ asserts low, and the output enters
auto-restart mode (see the Current-Limit Fault
Protection and Auto-Restart Mode sections). Only cur-
rent-limit and short-circuit faults are blanked. Thermal-
overload faults and input voltages below the UVLO
threshold immediately turn off the offending output and
assert FLT_ low.
Fault blanking allows the MAX1564 to handle USB
loads that might not be fully compliant with USB
specifications. The MAX1564 successfully powers USB
Figure 1. Typical Application Circuit
2.75V TO 5.5V
limit mode after the fault-blanking period (20ms typ)
expires.
blanking period expires.
INPUT
SELECT INPUT
ACTIVE-HIGH/
ACTIVE-LOW
0.1µF
C1
26.1kΩ
R1
16
1
3
4
2
5
SEL
ONA
ONB
SETI
INA
INB
INC
ONC
V CC
MAX1564
GND
OUTB
OUTC
OUTA
FLTC
FLTA
FLTB
R2
100kΩ
C2
1µF
C3
1µF
C4
1µF
100kΩ
R3
100kΩ
R4
USB
PORT B
USB
PORT A
USB
PORT C