MIC37100-1.5BM MICREL [Micrel Semiconductor], MIC37100-1.5BM Datasheet - Page 12

• Manufacturer Part Number: MIC37100-1.5BM
• Description: 1A LOW VOLTAGE U CAP LDO REGULATOR
• Manufacturer: MICREL [Micrel Semiconductor]

MIC37100/37101/37102
Minimum Load Current
The MIC37100/01/02 regulator is specified between finite
loads. If the output current is too small, leakage currents
dominate and the output voltage rises. A 10mA minimum load
current is necessary for proper regulation.
Adjustable Regulator Design
The MIC37102 allows programming the output voltage any-
where between 1.24V and the 6V maximum operating rating
of the family. Two resistors are used. Resistors can be quite
large, up to 1M , because of the very high input impedance
and low bias current of the sense comparator: The resistor
values are calculated by:
Where V
component definition. Applications with widely varying load
currents may scale the resistors to draw the minimum load
current required for proper operation (see above).
Power SOIC-8 Thermal Characteristics
One of the secrets of the MIC37101/02’s performance is its
power SO-8 package featuring half the thermal resistance of
a standard SO-8 package. Lower thermal resistance means
more output current or higher input voltage for a given
package size.
Lower thermal resistance is achieved by joining the four
ground leads with the die attach paddle to create a single-
piece electrical and thermal conductor. This concept has
M9999-091604
Figure 2. Adjustable Regulator with Resistors
R1 R2
O
SHUTDOWN
is the desired output voltage. Figure 2 shows
ENABLE
1.240
V
OUT
V
IN
V
OUT
1
IN
EN
MIC37102
1.240V 1
GND
OUT
ADJ
R2
R1
R1
R2
C
OUT
V
OUT
12
been used by MOSFET manufacturers for years, proving
very reliable and cost effective for the user.
Thermal resistance consists of two main elements,
(junction-to-case thermal resistance) and
ent thermal resistance). See Figure 3.
from the die to the leads of the package.
from the leads to the ambient air and it includes
sink thermal resistance) and
resistance).
Using the power SOIC-8 reduces the
allows the user to reduce
factor in calculating the maximum power dissipation capabil-
ity of the device. Typically, the power SOIC-8 has a
20 C/W, this is significantly lower than the standard SOIC-8
which is typically 75 C/W.
through 8 can now be soldered directly to a ground plane
which significantly reduces the case-to-sink thermal resis-
tance and sink to ambient thermal resistance.
Low-dropout linear regulators from Micrel are rated to a
maximum junction temperature of 125 C. It is important not
to exceed this maximum junction temperature during opera-
tion of the device. To prevent this maximum junction tempera-
ture from being exceeded, the appropriate ground plane heat
sink must be used.
JA
(junction-to-ambient thermal resistance) is the limiting
Figure 3. Thermal Resistance
printed circuit board
SOIC-8
JC
CA
JA
CA
. The total thermal resistance,
CA
SA
is reduced because pins 5
(sink-to-ambient thermal
AMBIENT
JC
JC
CA
heat sink area
ground plane
CA
September 2004
dramatically and
is the resistance
is the resistance
(case-to-ambi-
CS
(case-to-
Micrel
JC
JC
of