MIC2040-1BMM Micrel Inc, MIC2040-1BMM Datasheet - Page 11

• Manufacturer Part Number: MIC2040-1BMM
• Description: IC DISTRIBUTION SW SGL 10-MSOP
• Manufacturer: Micrel Inc
• Type: High Side Switchr

Specifications of MIC2040-1BMM

• Number Of Outputs: 1
• Rds (on): 75 mOhm
• Internal Switch(s): Yes
• Current Limit: Adjustable
• Voltage - Input: 0.8 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Functional Description
The MIC2040 and MIC2041 are high-side N-Channel switches
equipped with programmable current limit up to 1.5A for use
in general purpose power distribution applications. The
switches, available with active-high or active-low enable
inputs, operate down to 0.8V and provide circuit protection via
thermal shutdown and an optional output latch during
overcurrent conditions.
Input and Output
VBIAS supplies power to the internal circuitry of the switch
and must be present for the switch to operate. VIN is con-
nected to the drain of the output MOSFET and sources power
to the switched load. VIN must be less than or equal to VBIAS.
VOUT is the source terminal of the output MOSFET and
attaches to the load. In a typical circuit, current flows from VIN
to VOUT toward the load. If VOUT is greater than VIN, current
will flow from VOUT to VIN since the switch is bi-directional
when the device is enabled. When disabled (OFF), the switch
will block current flow from either direction.
Enable Input
Enable, the ON/OFF control for the output switch, is a digital
input available as an active-high (–1) or active-low (–2)
signal. The EN pin, referenced to approximately 0.5 × VBIAS,
must be driven to a clearly defined logic high or logic low.
Failure to observe this requirement, or allowing EN to float,
will cause the MIC2040/41 to exhibit unpredictable behavior.
EN should not be allowed to go negative with respect to
ground, nor allowed to exceed VBIAS. Failure to adhere to
these conditions may result in damage to the device.
Undervoltage Lockout
When the switch is enabled, undervoltage lockout (UVLO)
monitors the input voltage, VIN, and prevents the output
MOSFET from turning on until VIN exceeds a predetermined
level, nominally set at 1.45V. The UVLO threshold is adjust-
able and can be varied by applying an external resistor divider
to the UVLOIN pin from VIN to GND. The resistive divider
network is required when the input voltage is below 1.5V. The
UVLO threshold is internally preset to 1.45V if the UVLOIN
pin is left open. See “Applications Information.”
January 2005
MIC2040/2041
Figure 3. Current Limit Factor
2.25
1.75
1.25
0.75
0.25
2.5
1.5
0.5
2
1
0
CLF (LO)
Current Limit vs. R
CLF (HI)
R
V
–40°C to +85°C
SET
11
IN
= 1.6V to 5V
(Ω)
Programmable Current Limit
The MIC2040/41 is designed to prevent damage to the
external load by limiting the maximum amount of current it
can draw. The current limit is programmed by an external
resistor (R
active when the output voltage is at least 200mV below the
voltage at the input to the device. The limiting current value
is defined by the current limit factor (CLF) divided by R
and the MIC2040/41 will limit from 0.25A to 1.5A with a set
point accuracy of ±18%. In programming the nominal current
limit, the value of R
equation:
And given the ±18% tolerance of the current limit factor (CLF),
the external resistor is bound by:
The graph below (Figure 3) displays the current limit factor
characteristic over the full temperature and voltage range
indicated on the graph. This curve can be used as a point of
reference in determining the maximum variation in the device’s
current limit over the full temperature range. For example:
With V
= 340Ω), the low and high current limit settings for the
MIC2040/41 would be approximately 0.82A and 1.18A, re-
spectively, as shown on the graph using the 340Ω reference.
The MIC2041 is equipped with an internal circuit breaker for
overcurrent protection. During an overcurrent event which
exceeds the flag delay, the /FAULT output is asserted and the
MIC2041 latches the output off. Once the overcurrent load is
removed, the output automatically resets.
SET
187Ω ≤ R
R
IN
SET
= V
SET
=
BIAS
) connected from ILIM to ground and becomes
CLF
I
LIM
SET
= 3.0V and a nominal 1A current limit (R
=
≤ 1.6kΩ
SET
(
340A
I
is determined using the following
LIM
× Ω
)
M9999-012004
Micrel
SET
(1)
(2)
SET
,