MIC2074-2YM Micrel Inc, MIC2074-2YM Datasheet - Page 13

• Manufacturer Part Number: MIC2074-2YM
• Description: IC PWR DISTRIBUTION SW 2CH 8SOIC
• Manufacturer: Micrel Inc
• Type: High Side Switchr

Specifications of MIC2074-2YM

• Number Of Outputs: 2
• Rds (on): 170 mOhm
• Internal Switch(s): Yes
• Current Limit: 700mA
• Voltage - Input: 2.7 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-3443-5

Application Information
Supply Filtering
A 0.1µF to 1µF bypass capacitor positioned close to V
and GND of the device 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.
Printed Circuit Board Hot-Plug
The MIC2073/2074 are ideal inrush current-limiters for
hot plug applications. Due to their integrated charge
pumps, the MIC2073/2074 present a high impedance
when off and slowly becomes a low impedance as their
integrated charge pumps turn on. This “soft-start” feature
effectively isolates power supplies from highly capacitive
loads by reducing inrush current. Figure 3 shows how
the MIC2074 may be used in a card hot-plug application.
In cases of extremely large capacitive loads (>400µF),
the length of the transient due to inrush current may
exceed the delay provided by the integrated filter. Since
this inrush current exceeds the current-limit delay
specification, FLG will be asserted during this time. To
prevent the logic controller from responding to FLG
being asserted, an external RC filter, as shown in Figure
4, can be used to filter out transient FLG assertion. The
value of the RC time constant should be selected to
match the length of the transient, less t
MIC2073/2074.
Micrel, Inc.
January 2009
I
V
I
V
LOAD
LIMIT
I
V
OUT
OUT
FLG
EN
3ms typ.
delay
D(min)
Figure 2. MIC2073-2 Fault Timing
Short-Circuit Fault
of the
Shutdown
Reached
Thermal
IN
13
Universal Serial Bus (USB) Power Distribution
The MIC2073/2074 are ideally suited for USB (Universal
Serial Bus) power distribution applications. The USB
specification defines power distribution for USB host
systems such as PCs and USB hubs. Hubs can either
be self-powered or bus-powered (that is, powered from
the bus). Figure 5 shows a typical USB Host application
that may be suited for mobile PC applications employing
USB. The requirement for USB host systems is that the
port must supply a minimum of 500mA at an output
voltage of 5V ±5%. In addition, the output power
delivered must be limited to below 25VA. Upon an
overcurrent condition, the host must also be notified. To
support hot-plug events, the hub must have a minimum
of 120µF of bulk capacitance, preferably low ESR
electrolytic or tantalum. Please refer to Application Note
17 for more details on designing compliant USB hub and
host systems.
For bus-powered hubs, USB requires that each
downstream port be switched on or off under control by
the host. Up to four downstream ports each capable of
supplying 100mA at 4.4V minimum are allowed. In
addition, to reduce voltage droop on the upstream V
soft-start is necessary. Although the hub can consume
up to 500mA from the upstream bus, the hub must
consume
enumerates with the host prior to requesting more
power. The same requirements apply for bus-powered
peripherals that have no downstream ports. Figure 6
shows a bus-powered hub.
Load and Fault Removed
only
(Output Reset)
100mA
max
at start-up,
MIC2073/2074
M9999-011209
until
BUS
it
,