MAX1940EEE+ Maxim Integrated Products, MAX1940EEE+ Datasheet - Page 11

• Manufacturer Part Number: MAX1940EEE+
• Description: IC SW USB TRPL 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1940EEE+

• Applications: USB, Peripherals
• Current - Supply: 60µA
• Voltage - Supply: 4 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 2. Typical Application Circuit
power bus with short traces. Wide power bus planes at
IN_ and OUT provide superior heat dissipation as well.
O.1µF
4V TO 5.5V
ON
INPUT
OFF
*USB APPLICATIONS MAY REQUIRE
ADDITIONAL BULK CAPACITANCE
IN1
IN2
IN3
IN4
IN5
ONA
ONB
ONC
SEL
______________________________________________________________________________________
MAX1940
GND
Triple USB Switch with Autoreset and
FAULTB
FAULTC
FAULTA
OUTC
OUTA
OUTB
100kΩ
1µF*
1µF*
1µF*
USB
PORT A
USB
PORT B
USB
PORT C
100kΩ
100kΩ
An active switch dissipates little power with minimal
change in package temperature. Calculate the power
dissipation for this condition as follows:
At the normal operating current (I
maximum on-resistance of the switch (135mΩ), the
power dissipation is:
The worst-case power dissipation occurs when the output
current is just below the current-limit threshold (1.2A max)
with an output voltage greater than 1V. In this case, the
power dissipated in each switch is the voltage drop
across the switch multiplied by the current limit:
For a 5V input and 1V output, the maximum power dis-
sipation per switch is:
Because the package power dissipation is 667mW, the
MAX1940 die temperature exceeds the +160°C thermal
shutdown threshold, and the switch output shuts down
until the junction temperature cools by +15°C. The duty
cycle and period are strong functions of the ambient
temperature and the PC board layout (see the Thermal
Shutdown section).
If the output current exceeds the current-limit threshold,
or the output voltage is pulled below the short-circuit
detect threshold, the MAX1940 enters a fault state after
20ms, at which point autoreset mode is enabled and
25mA is sourced by the output. For a 5V input, OUT_
short-circuited to GND, and autoreset mode active, the
power dissipation is as follows:
P = (0.5A)
P = 1.2A x (5V - 1V) = 4.8W
P = 0.025A x 5V = 0.125W
P = I
2
P = (I
x 0.135Ω = 34mW per switch.
Fault Blanking
LIM
OUT_
x (V
)
IN
2
x R
- V
OUT_
ON
OUT
)
= 0.5A) and the
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