MIC2548A-1YM Micrel Inc, MIC2548A-1YM Datasheet - Page 16

• Manufacturer Part Number: MIC2548A-1YM
• Description: IC SW CURR LIMIT HI SIDE 8SOIC
• Manufacturer: Micrel Inc
• Type: High Sider

Specifications of MIC2548A-1YM

• Input Type: Non-Inverting
• Number Of Outputs: 1
• On-state Resistance: 80 mOhm
• Current - Peak Output: 1.5A
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output / Channel: -
• Other names: 576-3608-5

Application Information
Supply Filtering
A minimum 1μF bypass capacitor from IN-to-GND,
located near the MIC2544A and MIC2548A, is strongly
recommended to control supply transients. Without a
bypass capacitor, an output short may cause sufficient
ringing on the input (from supply lead inductance) to
damage internal control circuitry. An additional 22µF
input capacitor placed close to the IC is required if a bulk
input capacitor is further than 3 inches away from the IC.
Input transients must not exceed the absolute
maximum supply voltage (V
duration.
Power Dissipation
The device's junction temperature depends upon several
factors such as the load, PCB layout, ambient
temperature, and package type. Equations that can be
used to calculate power dissipation and junction
temperature are found below.
Calculation of power dissipation can be accomplished by
the following equation:
To relate this to junction temperature, the following
equation can be used:
where:
Transient Over Current Filter
The inrush current from the connection of a heavy
capacitive load may cause the fault flag to fall for 10μs to
200μs while the switch is in a constant-current mode,
charging the capacitance, as shown in Figure 4.
Micrel, Inc.
April 2010
P
T
T
T
θ
JA
j
j
A
D
= P
= junction temperature
= ambient temperature
= R
= is the thermal resistance of the package
D
DS(on)
× θ
Figure 3. Supply Bypassing
JA
× (I
+ T
OUT
A
)
2
IN max
= 6V) even for a short
16
Adding an optional series resistor-capacitor (R
parallel with R
transient current-limit to be set to a different value than
steady-state. A typical USB hot-plug inrush is 2A to 3A
for 10μs to 20μs. If R
100Ω (2.3A) and C
transient surge of 3A to pass for 100μs without tripping
the over current flag (FLG), as shown in Figure 5.
Figure 6 circuit can also be used to filter out transient
FLG assertion. The value of the RC time constant should
be selected to match the length of transient. Figure 7
shows the FLAG pin waveform due to the inrush of
current surge.
Figure 5. ILIMIT Filter with C
Figure 4. Flag Glitch with C
SET
Figure 6. Flag Filter Circuit
, and as shown in Figure 8, allows the
SET
SET
of 1μF (RC = 100μs) allows
is 309Ω (525mA), an R
OUT
OUT
MIC2544A/2548A
= 120µF
= 120µF
M9999-043010
SET2
SET2
), in
of