© 1999 California Micro Devices Corp. All rights reserved.
9/99 215 Topaz Street, Milpitas, California 95035 Tel: (408) 263-3214 Fax: (408) 263-7846 www.calmicro.com 1
CMPWR150
CALIFORNIA MICRO DEVICES
500mA / 3.3V SmartOR POWER REGULATOR
Features Pin Diagrams
Automatic detection of VCC input supply
Drive output logic to control external switch
Glitch-free output during supply transitions
500mA output maximum load current
Built-in hysteresis during supply selection
Controller operates from either VCC or VOUT
8-pin SOIC Thermal or 5-pin TO-263 packages
Applications
PCI adapter cards
Network Interface Cards (NICs)
Dual power systems
Systems with standby capabilities
See Application Note AP-211
Product Description
California Micro Devices SmartORTM CMPWR150 is a
low dropout regulator that delivers up to 500mA of
load current at a fixed 3.3V output. An internal threshold
level (typically 4.1V) is used to prevent the regulator
from being operated below dropout voltage. The device
continuously monitors the input supply and will
automatically disable the regulator when VCC falls below
the threshold level. When the regulator is disabled, the
control signal Drive (Active Low) is enabled, which
allows an external PMOS switch to power the load from
an auxiliary 3.3V supply.
When VCC is restored to a level above the select threshold,
the control signal for the external PMOS switch is disabled
and the regulator is once again enabled.
All the necessary control circuitry needed to provide a
smooth and automatic transition between the supplies
has been incorporated. This allows VCC to be dynamically
switched without loss of output voltage.
The CMPWR150 is available in either an 8-pin SOIC
thermally enhanced package, ideal for space critical
applications, or a 5-pin TO-263 package.
C0590899
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Typical Application Circuit
Simplified Electrical Schematic
SmartOR is a trademark of California Micro Devices Corp.
CMPWR150
CMPWR150TO
5-pin TO-263 Package
CMPWR150SA
8-pin SOIC Thermal Package
n.c. GND
VCC GND
VOUT GND
Drive GND
n.c.
VCC
VOUT
GND
Drive
Top View
Top View
©1999 California Micro Devices Corp. All rights reserved.
9/99
215 Topaz Street, Milpitas, California 95035 Tel: (408) 263-3214 Fax: (408) 263-7846 www.calmicro.com
2
CMPWR150
CALIFORNIA MICRO DEVICES
Note 1: The SOIC package used is thermally enhanced through the use of a fused integral leadframe. The power rating is based on a printed
circuit board heat spreading capability equivalent to 2 square inches of copper connected to the GND pins. Typical multi-layer boards
using power plane construction will provide this heat spreading ability without the need for additional dedicated copper area. (Please
consult with factory for thermal evaluation assistance.)
Note 2: The hysteresis defines the maximum level of acceptable disturbance on VCC during switching. It is recommended that the VCC source
impedance be kept below 0.25
Ω
to ensure the switching disturbance remains below the hysteresis during select/deselect transitions.
An input capacitor may be required to help minimize the switching transient.
Note 3: Ground pin current consists of controller current (0.15mA) and regulator current if enabled. The controller always draws 0.15mA from
either VCC or VOUT , whichever is greater. All regulator current is supplied exclusively from VCC . At high load currents a small increase
occurs due to current limit protection circuitry.
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© 1999 California Micro Devices Corp. All rights reserved.
9/99 215 Topaz Street, Milpitas, California 95035 Tel: (408) 263-3214 Fax: (408) 263-7846 www.calmicro.com 3
CMPWR150
CALIFORNIA MICRO DEVICES
Interface Signals
VCC is the power source for the internal regulator and is
monitored continuously by an internal controller circuit.
Whenever VCC exceeds VCCSEL (4.35V typically), the internal
regulator (500mA max) will be enabled and deliver a fixed
3.3V at VOUT. When VCC falls below VCCDES (4.10V typically)
the regulator will be disabled
Internal loading on this pin is typically 1.0mA when the
regulator is enabled, which reduces to 0.15mA whenever
the regulator is disabled. If VCC falls below the voltage on
the VOUT pin the VCC loading will further reduce to only a
few microamperes.
During a VCC power up sequence, there will be an effective
step increase in VCC line current when the regulator is
enabled. The amplitude of this step increase will depend
on the dc load current and any necessary current required
for charging/discharging the load capacitance. This line
current transient will cause a voltage disturbance at the VCC
pin. The magnitude of the disturbance will be directly
proportional to the effective power supply source
impedance being delivered to the VCC input.
To prevent chatter during Select and Deselect transitions, a
built-in hysteresis voltage of 250mV has been incorporated.
It is recommended that the power supply connected to
the VCC input should have a source resistance of less than
0.25Ω to minimize the event of chatter during the enabling/
disabling of the regulator.
An input filter capacitor in close proximity to the VCC pin
will reduce the effective source impedance and help
minimize any disturbances. If the VCC pin is within a few
inches of the main input filter, a capacitor may not be
necessary. Otherwise an input filter capacitor in the range
of 1uF to 10uF will ensure adequate filtering.
GND is the negative reference for all voltages. The current
that flows in the ground connection is very low (typically
1.0mA) and has minimal variation over all load conditions.
VOUT is the regulator output voltage connection used to
power the load. An output capacitor of ten microfarads is
used to provide the necessary phase compensation, thereby
preventing oscillation. The capacitor also helps to minimize
the peak output disturbance during power supply
changeover.
When VCC falls below VOUT, then VOUT will be used to provide
the necessary quiescent current for the internal reference
circuits. This ensures excellent start-up characteristics for
the regulator.
DRIVE is an active LOW logic output intended to be used
as the control signal for driving an external PFET whenever
the regulator is disabled. This will allow the voltage at VOUT
to be powered from an auxiliary supply voltage (3.3V).
The Drive pin is pulled HIGH to VCC whenever the regulator
is enabled. This ensures that the auxiliary remains isolated
during normal regulator operation.
n.c. pins are electrically isolated from the internal circuitry.
These pins can be connected to any external voltage level
without impacting the device funtionality.
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©1999 California Micro Devices Corp. All rights reserved.
9/99
215 Topaz Street, Milpitas, California 95035 Tel: (408) 263-3214 Fax: (408) 263-7846 www.calmicro.com
4
CMPWR150
CALIFORNIA MICRO DEVICES
Typical DC Characteristics
Unless stated otherwise, all DC characteristics were
measured at room temperature with a nominal VCC supply
voltage of 5.0 volts and an output capacitance of 10µF.
The external PMOS switch was present and resistive load
conditions were used.
The test data shown here was obtained from engineering
samples. The device was modified to allow the regulator
to function below the dropout threshold for the purpose
of obtaining test data. During normal operation,
production parts will shutdown the regulator below a
4.1V supply.
Dropout Characteristics of the regulator are shown in
Figure 1. At maximum rated load conditions (500mA), a
100mV drop in regulation occurs when the line voltage
collapses below 4.1V. For light load conditions (50mA),
regulation is maintained for line voltages as low as 3.5V.
In normal operation, the regulator is deselected at 4.1V,
which ensures a regulation output droop of less than
100mV is maintained.
Figure 1. Dropout Characteristics.
Load Regulation performance is shown from zero to
maximum rated load in Figure 2. A change in load from
10% to 100% of rated, results in an output voltage change
of less than 75mV. This translates into an effective output
impedance of approximately 0.15Ω.
Ground Current is shown across the entire range of
load conditions in Figure 3. The ground current has
minimal variation across the range of load conditions and
shows only a slight increase at maximum load. This slight
increase at rated load is due to the current limit protection
circuitry becoming active.
Figure 2. Load Regulation.
Figure 3. Ground Current.
© 1999 California Micro Devices Corp. All rights reserved.
9/99 215 Topaz Street, Milpitas, California 95035 Tel: (408) 263-3214 Fax: (408) 263-7846 www.calmicro.com 5
CMPWR150
CALIFORNIA MICRO DEVICES
When VAUX is present, the VCC supply current is less than
10µA until VCC exceeds VAUX, at which point VCC then powers
the controller (0.15mA). When VCC reaches VSELECT, the
regulator is enabled.
Typical Transient Characteristics
The transient characterization test set-up shown below
includes the effective source impedance of the VCC supply
(RS). This was measured to be approximately 0.2Ω. It is
recommended that this effective source impedance be no
greater than 0.25Ω to ensure precise switching is maintained
during VCC selection and deselection.
Both the rise and fall times during VCC power-up/down
sequencing were controlled at a 20 millisecond duration.
This is considered to represent worst case conditions for
most application circuits.
A maximum rated load current of 500mA was used during
characterization, unless specified otherwise.
Typical DC Characteristics (continued)
Figure 4. VCC Supply Current (No Load).
During a selection or deselection transition, the DC load
current is switching from VAUX to VCC and vice versa. In
addition to the normal load current, there may also be an
in-rush current for charging/discharging the load capacitor.
The total current pulse being applied to either VAUX or VCC is
equal to the sum of the dc load and the corresponding in-
rush current. Transient currents in excess of 1.0 amps can
readily occur for brief intervals when either supply
commences to power the load.
The oscilloscope traces of VCC power-up/down show the
full bandwidth response at the VCC and VOUT pins under full
load (500mA) conditions.
See Application Note AP-211 for more information.
VCC Power-up Cold Start. Figure 5 shows the output
response during an initial VCC power-up with VAUX not
present. When VCC reaches the select threshold, the
regulator turns on. The uncharged output capacitor causes
maximum in-rush current to flow, resulting in a large
voltage disturbance at the VCC pin of about 230mV. The
built-in hysteresis of 250mV ensures the regulator remains
enabled throughout the transient.
Prior to VCC reaching an acceptable logic supply level (2V),
a disturbance on the Drive pin can be observed.
Figure 5. VCC Power-up Cold Start.
F
VCC Supply Current of the device is shown across the entire VCC
range for both VAUX present (3.3V) and absent (0V) in Figure 4.
In the absence of VAUX, the supply current remains fixed at
approximately 0.15mA until VCC reaches the Select voltage
threshold of 4.35V. At this point the regulator is enabled
and a supply current of 1.0mA is conducted.
Transient Characteristics Test Set-up
CMPWR150
©1999 California Micro Devices Corp. All rights reserved.
9/99
215 Topaz Street, Milpitas, California 95035 Tel: (408) 263-3214 Fax: (408) 263-7846 www.calmicro.com
6
CMPWR150
CALIFORNIA MICRO DEVICES
VCC Power-up (VAUX =3.3V). Figure 6 shows the output
response as VCC approaches the select threshold during a
power-up when VAUX is present (3.3V). The output capacitor
is already fully charged. When VCC reaches the select threshold,
the in-rush current is minimal and the VCC disturbance is only
130mV. The built-in hysteresis of 250mV ensures the regulator
remains enabled throughout the transient.
VOUT offset = 3.3V, VCC offset = 4.3V
VCC Power-up (VAUX =3.0V). Figure 7 shows the output
response as VCC approaches the select threshold during
power-up. The auxiliary voltage, VAUX is set to a low level
of 3.0V. When VCC reaches the select threshold, a modest
level of in-rush current is required to further charge the
output capacitor resulting in VCC disturbance of 200mV.
The built-in hysteresis of 250mV ensures the regulator
remains enabled throughout the transient.
VOUT offset = 3.3V, VCC offset = 4.3V
Typical Transient Characteristics (continued)
Figure 6. VCC Power-up (VAUX =3.3V).
VCC Power-down (VAUX = 3.3V). Figure 8 shows the
output response as VCC approaches the deselect threshold
during a power-down transition. VAUX of 3.3V remains
present. When VCC reaches the deselect threshold (4.1V),
the regulator turns off. This causes a step change reduction
in VCC current resulting in a small voltage increase at the
VCC input. This disturbance is approximately 100mV and
the built-in hysteresis of 250mV ensures the regulator
remains disabled throughout the transient. The output
voltage experiences a disturbance of approximately 100mV
during the transition.
VOUT offset = 3.3V, VCC offset = 4.3V
Figure 7. VCC Power-up (VAUX =3.0V).
Figure 8. VCC Power-down (VAUX = 3.3V).
© 1999 California Micro Devices Corp. All rights reserved.
9/99 215 Topaz Street, Milpitas, California 95035 Tel: (408) 263-3214 Fax: (408) 263-7846 www.calmicro.com 7
CMPWR150
CALIFORNIA MICRO DEVICES
VCC Power-down (VAUX = 0V). Figure 9 shows the
output response of the regulator during a complete
power-down situation under full load conditions.
Once VCC falls below an acceptable logic supply level
(2V), a disturbance on the Drive pin can be observed.
Drive offset = 5.0V
Load Step Response. Figure 10 shows the output
response of the regulator during a step load change from
5mA to 500mA (represented on Ch1). An initial transient
overshoot of 50mV occurs and the output settles to its
final voltage within a few microseconds. The dc voltage
disturbance on the output is approximately 75mV, which
demonstrates the regulator output impedance of 0.15Ω.
VOUT offset = 3.3V
Typical Transient Characteristics (continued)
Figure 9. VCC Power-down (VAUX = 0V).
Figure 10. Load Step Response.
Typical Thermal Characteristics
Thermal dissipation of junction heat consists primarily of
two paths in series. The first path is the junction to the case
(θ
JC) thermal resistance, which is defined by the package
style, and the second path is the case to ambient (θ
CA) thermal
resistance, which is dependent on board layout.
For a given package style and board layout, the operating
junction temperature is a function of junction power
dissipation PJUNC and the ambient temperature, resulting in
the following thermal equation:
TJUNC = TAMB + PJUNC (θ
JC ) + PJUNC (θ
CA)
The TO-263 style package has θ
JC of 3°C/W and when
mounted, using minimum pad layout with tab soldered
down, produces a θ
CA of 48°C/W. Based on maximum power
dissipation of 1.0W (2Vx500mA) with an ambient of 70°C
the resulting junction temperature will be:
TJUNC = TAMB + PJUNC (θ
JC ) + PJUNC (θ
CA)
= 70°C + 1.0W (3°C/W) + 1.0W (48°C/W)
= 70°C + 3.0°C + 48°C
= 121°C
Figure 11. Line Step Response.
Line Step Response. Figure 11 shows the output response
of the regulator to a VCC line voltage transient between 4.5V
and 5.5V (1Vpp as shown on Ch1). The load condition during
this test is 5mA. The output response produces less than
10mV of disturbance on both edges indicating a line rejection
of better than 40dB at high frequencies.
VOUT offset = 3.3V
©1999 California Micro Devices Corp. All rights reserved.
9/99
215 Topaz Street, Milpitas, California 95035 Tel: (408) 263-3214 Fax: (408) 263-7846 www.calmicro.com
8
CMPWR150
CALIFORNIA MICRO DEVICES
The CMPWR150TO therefore requires no additional heat
sinking. All thermal characteristics were measured with the
TO-263 package using minimum size solder pads and tab.
Measurements showing performance up to maximum
junction temperature of 125°C were performed under light
load conditions (5mA). This allows the ambient
temperature to be representative of the internal junction
temperature.
Output Voltage vs. Temperature. Figure 12 shows
the regulator VOUT performance up to the maximum rated
junction temperature. The overall 100°C variation in
junction temperature causes an output voltage change of
about 30mV, reflecting a voltage temperature coefficient
of 90ppm/°C.
Output Voltage (500mA) vs. Temperature. Figure 13
shows the regulator steady state performance when fully
loaded (500mA) in an ambient temperature up to the rated
maximum of 70°C. The output variation at maximum load is
approximately 25mV across the normal temperature range.
Typical Thermal Characteristics (continued)
Figure 12. Output Voltage vs. Temperature.
Thresholds vs. Temperature. Figure 14 shows the
regulator select/deselect threshold variation up to the
maximum rated junction temperature. The overall 100°C
change in junction temperature causes a 30mV variation
in the select threshold voltage (regulator enable). The
deselect threshold level varies about 50mV over the 100°C
change in junction temperature. This results in the built-
in hysteresis having minimal variation over the entire
operating junction temperature range.
Figure 14. Thresholds vs. Temperature.
Figure 13. Output Voltage (500mA) vs. Temperature.