MIC37301-1.5WR TR Micrel Inc, MIC37301-1.5WR TR Datasheet - Page 10

• Manufacturer Part Number: MIC37301-1.5WR TR
• Description: 3A Low Voltage LDO Regulator( )
• Manufacturer: Micrel Inc

Specifications of MIC37301-1.5WR TR

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.5V
• Voltage - Input: 2.25 ~ 6 V
• Number Of Regulators: 1
• Current - Output: 3A (Min)
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SPAK-5
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Dropout (typical): -
• Current - Limit (min): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MIC37301-1.5WRTR; MIC37301-1.5WRTR

October 2009
Transient Response and 3.3V to 2.5V, 2.5V to 1.8V
or 1.65V, or 2.5V to 1.5V Conversions
The
response to variations in input voltage and load
current. The device has been designed to respond
quickly to load current variations and input voltage
variations. Large output capacitors are not required to
obtain this performance. A standard 47µF output
capacitor, preferably tantalum, is all that is required.
Larger values help to improve performance even
further.
By virtue of its low-dropout voltage, this device does
not saturate into dropout as readily as similar NPN-
based designs. When converting from 3.3V to 2.5V,
2.5V to 1.8V or 1.65V, or 2.5V to 1.5V, the NPN-
based regulators are already operating in dropout,
with typical dropout requirements of 1.2V or greater.
To convert down to 2.5V without operating in dropout,
NPN-based regulators require an input voltage of 3.7V
at the very least. The MIC37300/01/02/03 regulator
will provide excellent performance with an input as low
as 3.0V or 2.25V, respectively. This gives the PNP-
based regulators a distinct advantage over older,
NPN-based linear regulators.
Minimum Load Current
The
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 operation.
Error Flag
The MIC37301 and MIC37303 feature an error flag
circuit that monitors the output voltage and signals an
error condition when the voltage is 5% below the
nominal output voltage. The error flag is an open-
collector output that can sink 10mA during a fault
condition.
Low output voltage can be caused by a number of
problems, including an overcurrent fault (device in
current limit) or low input voltage. The flag is
inoperative during overtemperature shutdown.
MIC37300/01/02/03 has
MIC37300/01/02/03
regulator
excellent
is
specified
transient
10
Enable Input
The MIC37301/02/03 also features an enable input for
on/off control of the device. Its shutdown state draws
“zero” current (only microamperes of leakage). The
enable input is TTL/CMOS compatible for simple logic
interface, but can be connected up to VIN. When
enabled, it draws approximately 15µA.
Adjustable Regulator Design
The MIC37302 and MIC37303 allow programming the
output voltage any-where between 1.24V and the
5.5V maximum operating rating of the family. Two
resistors are used. Resistors can be quite large, up to
1MΩ, because of the very high input impedance and
low bias current of the sense comparator. The resistor
values are calculated by:
Where V
shows component definition. Applications with widely
varying load currents may scale the resistors to draw
the minimum load current required for proper
operation (see above).
SHUTDOWN
Figure 1. Adjustable Regulator with Resistors
ENABLE
R1
OUT
=
V
IN
R2
is the desired output voltage. Figure 1
V
⎛
⎜ ⎜
⎝
OUT
1.240
V
OUT
IN
EN
MIC37302
=
1.240V 1
GND
−
1
⎞
⎟ ⎟
⎠
OUT
ADJ
⎛
⎜
⎝
+
R2
R1
⎞
⎟
⎠
R1
R2
M9999-102909
C
OUT
V
OUT