MIC5332-G4YMT TR Micrel Inc, MIC5332-G4YMT TR Datasheet - Page 8

• Manufacturer Part Number: MIC5332-G4YMT TR
• Description: Micro-Power High Performance Dual 300mA ULDOT
• Manufacturer: Micrel Inc

Specifications of MIC5332-G4YMT TR

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.8V, 1.2V
• Voltage - Input: 2.3 ~ 5.5 V
• Voltage - Dropout (typical): 0.12V @ 300mA
• Number Of Regulators: 2
• Current - Output: 300mA
• Current - Limit (min): 350mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MLF®, QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-3157-2

Application Information
MIC5332 is a dual 300mA LDO, with an integrated
Power On Reset (POR) for the second regulator. The
MIC5332 regulator is fully protected from damage due to
fault conditions, offering linear current limiting and
thermal shutdown.
Input Capacitor
The MIC5332 is a high-performance, high bandwidth
device. Therefore, it requires a well-bypassed input
supply for optimal performance. A 1µF capacitor is
required from the input to ground to provide stability.
Low-ESR
performance at a minimum of space. Additional high-
frequency capacitors, such as small-valued NPO
dielectric-type capacitors, help filter out high-frequency
noise and are good practice in any RF-based circuit.
X5R or X7R dielectrics are recommended for the input
capacitor. Y5V dielectrics lose most of their capacitance
over temperature and are therefore, not recommended.
Output Capacitor
The MIC5332 requires an output capacitor of 1µF or
greater to maintain stability. The design is optimized for
use with low-ESR ceramic chip capacitors. High ESR
capacitors may cause high frequency oscillation. The
output capacitor can be increased, but performance has
been optimized for a 1µF ceramic output capacitor and
does not improve significantly with larger capacitance.
X7R/X5R
recommended
performance. X7R-type capacitors change capacitance
by 15% over their operating temperature range and are
the most stable type of ceramic capacitors. Z5U and
Y5V dielectric capacitors change value by as much as
50% and 60%, respectively, over their operating
temperature ranges. To use a ceramic chip capacitor
with Y5V dielectric, the value must be much higher than
an X7R ceramic capacitor to ensure the same minimum
capacitance over the equivalent operating temperature
range.
No-Load Stability
Unlike many other voltage regulators, the MIC5332 will
remain stable and in regulation with no load. This is
especially import in CMOS RAM keep-alive applications.
Enable/Shutdown
The MIC5332 comes with dual active-high enable pins
that allow each regulator to be disabled independently.
Forcing the enable pin low disables the regulator and
sends it into a “zero” off-mode-current state. In this state,
current consumed by the regulator goes nearly to zero.
Forcing the enable pin high enables the output voltage.
The active-high enable pin uses CMOS technology and
Micrel, Inc.
April 2008
dielectric-type
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8
the enable pin cannot be left floating; a floating enable
pin may cause an indeterminate state on the output.
Power On Reset
The second regulator has a Power On Reset status pin
(POR2). This pin is an open drain output. When LDO2 is
enabled an active low POR2 indicates an under voltage
condition on V
The POR2 status signal can be programmed for a delay
of 1sec/µF by placing a capacitor from the CSET2 pin to
ground. Zero delay is added by leaving the CSET2 pin
open circuit.
Thermal Considerations
The MIC5332 is designed to provide 300mA of
continuous current for both outputs in a very small
package. Maximum ambient operating temperature can
be calculated based upon the output current and the
voltage drop across the part. For example if the input
voltage is 3.6V, the output voltage is 3.0V for V
for V
power dissipation of the regulator circuit can be
determined using the equation:
Because this device is CMOS and the ground current is
typically <100µA over the load range, the power
dissipation contributed by the ground current is < 1%
and can be ignored for this calculation.
To
temperature of the package, use the junction-to-ambient
thermal resistance of the device and the following basic
equation:
T
of the die, θ
Substituting P
operating temperature will give the maximum operating
conditions for the regulator circuit. The junction-to-
ambient thermal resistance for the minimum footprint is
90°C/W.
The maximum power dissipation must not be exceeded
for proper operation.
For example, when operating the MIC5332-PMYMT at
an input voltage of 3.6V and 300mA loads at each output
with a minimum footprint layout, the maximum ambient
operating temperature T
J(max)
P
P
D
D
OUT2
determine
= (V
= (3.6V – 3.0V) × 300mA + (3.6V -2.8) × 300mA
= 125°C, and the maximum junction temperature
P
0.42W = (125°C – T
T
P
A
D
D(MAX)
IN
and the output current = 300mA. The actual
= 87.2°C
= 0.42W
JA
– V
, thermal resistance = 90°C/W.
OUT2
D
OUT1
=
for P
the
.
⎛
⎜
⎜
⎝
) I
T
J(MAX)
OUT1
D(max)
θ
maximum
A
JA
+ (V
can be determined as follows:
−
and solving for the ambient
A
T
)/(90°C/W)
IN
A
⎞
⎟
⎟
⎠
– V
OUT2
ambient
) I
M9999-042108-B
OUT2
+ V
MIC5332
OUT1
operating
IN
, 2.8V
I
GND