Micrel MIC23031-FYMT 4mhz pwm 400ma buck regulator with hyperlight load Datasheet

MIC23031
4MHz PWM 400mA Buck Regulator with
HyperLight Load™
General Description
Features
The MIC23031 is a high-efficiency 4MHz 400mA
synchronous buck regulator with HyperLight Load™ mode.
HyperLight Load™ provides very-high efficiency at light
loads and ultra-fast transient response which is perfectly
suited for supplying processor core voltages. An additional
benefit of this proprietary architecture is very-low output
ripple voltage throughout the entire load range with the use
of small output capacitors. The tiny 1.6mm x 1.6mm Thin
MLF® package saves precious board space and requires
only three external components.
The MIC23031 is designed for use with a very-small
inductor, down to 0.47µH, and an output capacitor as small
as 2.2µF that enables a sub-1mm height.
The MIC23031 has a very-low quiescent current of 21µA
and achieves as high as 88% efficiency at 1mA. At higher
loads, the MIC23031 provides a constant switching
frequency around 4MHz while achieving peak efficiencies
up to 93%.
The MIC23031 is available in a 6-pin 1.6mm x 1.6mm Thin
MLF® package with an operating junction temperature
range from –40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
•
•
•
•
•
•
•
•
•
•
•
Input voltage: 2.7V to 5.5V
400mA output current
Up to 93% efficiency and 88% at 1mA
21µA typical quiescent current
4MHz PWM operation in continuous mode
Ultra-fast transient response
Low voltage output ripple
– 20mVpp ripple in HyperLight Load™ mode
– 3mV output voltage ripple in full PWM mode
0.01µA shutdown current
Fixed and adjustable output voltage options available
6-pin 1.6mm x 1.6mm Thin MLF®
–40°C to +125°C junction temperature range
Applications
•
•
•
•
•
•
•
•
Mobile handsets
Portable media/MP3 players
Portable navigation devices (GPS)
WiFi/WiMax/WiBro modules
Digital Cameras
Wireless LAN cards
USB-powered devices
Portable applications
Typical Application
HyperLight Load is a trademark of Micrel, Inc
MLF and MicroLead Frame are registered trademarks of Amkor Technology, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
October 2010
M9999-102210-A
Micrel Inc.
MIC23031
Ordering Information
Marking
Code
Nominal
Output Voltage
Junction
Temperature Range
Package
MIC23031-AYMT
GEA
Adjustable
−40°C to +125°C
6-Pin 1.6mm × 1.6mm Thin MLF®
Pb-Free
MIC23031-GYMT
GEG
1.8V
−40°C to +125°C
®
Pb-Free
®
Pb-Free
®
Pb-Free
®
Pb-Free
Part Number
MIC23031-FYMT
GEF
MIC23031-4YMT
1.5V
GE4
MIC23031-CYMT
1.2V
GEC
1.0V
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Lead Finish
6-Pin 1.6mm × 1.6mm Thin MLF
6-Pin 1.6mm × 1.6mm Thin MLF
6-Pin 1.6mm × 1.6mm Thin MLF
6-Pin 1.6mm × 1.6mm Thin MLF
Notes:
1.
Other options available. Contact Micrel for details.
2.
Thin MLF is GREEN RoHS-compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
®
Pin Configuration
VIN
1
6
PGND
VIN
1
6
GND
SW
2
5
AGND
SW
2
5
FB
SNS
3
4
EN
SNS
3
4
EN
6-Pin 1.6 x 1.6mm Thin MLF® (MT)
Fixed (Top View)
6-Pin 1.6 x 1.6mm Thin MLF® (MT)
Adjustable (Top View)
Pin Description
Fixed
Option
Adjustable
Option
Pin Name
1
1
VIN
Input Voltage: Connect a capacitor to ground to decouple the noise.
2
2
SW
Switch (Output): Internal power MOSFET output switches.
3
3
SNS
Sense: Connect to VOUT as close to output capacitor as possible to sense output
voltage.
4
4
EN
5
−
AGND
−
5
FB
6
−
PGND
−
6
GND
ePad
ePad
HS PAD
October 2010
Pin Function
Enable (Input): Logic high enables operation of the regulator. Logic low will shut down
the device. Do not leave floating.
Analog Ground: Connect to central ground point where all high current paths meet
(CIN, COUT, PGND) for best operation.
Feedback (Input): Connect resistor divider at this node to set output voltage. Resistors
should be selected based on a nominal VFB of 0.62V.
Power Ground.
Ground.
Connect to PGND or GND.
2
M9999-102210-A
Micrel, Inc.
MIC23031
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) . ……………………………………….6V
Sense (VSNS).. ..................................................................6V
Output Switch Voltage ..................................................6V
Enable Input Voltage (VEN)................................−0.3V to VIN
Storage Temperature Range ..……………−65°C to +150°C
ESD Rating(3) ................................................. ESD Sensitive
Supply Voltage (VIN)... …………………………..2.7V to 5.5V
Enable Input Voltage (VEN) .. ……………………….0V to VIN
Output Voltage Range (VSNS) ………………….0.7V to 3.6V
Junction Temperature Range (TJ).. ….−40°C ≤ TJ ≤ +125°C
Thermal Resistance
1.6 x 1.6mm Thin MLF®-6 (θJA).......................92.4°C/W
Electrical Characteristics(4)
TA = 25°C; VIN = VEN = 3.6V; L = 1µH; COUT = 4.7µF unless otherwise specified.
Bold values indicate –40°C ≤ TJ ≤ +125°C, unless noted.
Parameter
Condition
Min.
Under-Voltage Lockout Threshold
(Turn-on)
2.45
Quiescent Current
IOUT = 0mA , SNS > 1.2 * VOUT Nominal
Shutdown Current
VEN = 0V, VIN = 5.5V
Output Voltage Accuracy
VIN = 3.6V; ILOAD = 20mA
Feedback Voltage
Adjustable Option Only
Current Limit
SNS = 0.9*VOUTNOM
Output Voltage Line Regulation
VIN = 3.0V to 5.5V, VOUT = 1.2V, ILOAD = 20mA,
0.3
%/V
Output Voltage Load Regulation
20mA < ILOAD < 400mA, VOUT = 1.2V,
VIN = 3.6V
0.7
%
ISW = 100mA PMOS
0.65
ISW = −100mA NMOS
0.8
Supply Voltage Range
PWM Switch ON-Resistance
Typ.
Max.
Units
5.5
V
2.55
2.65
V
21
35
µA
0.01
4
µA
+2.5
%
2.7
Frequency
IOUT = 120mA
Soft-Start Time
VOUT = 90%
−2.5
0.62
0.41
0.7
V
1
Ω
4
MHz
100
Enable Threshold
A
µs
0.9
1.2
V
Enable Input Current
0.1
2
µA
Over-Temperature Shutdown
160
°C
Over-Temperature Shutdown Hysteresis
20
°C
0.5
Notes:
1.
Exceeding the absolute maximum rating may damage the device.
2.
The device is not guaranteed to function outside its operating rating.
3.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF.
4.
Specification for packaged product only.
October 2010
3
M9999-102210-A
Micrel, Inc.
MIC23031
Typical Characteristics
October 2010
4
M9999-102210-A
Micrel, Inc.
MIC23031
Typical Characteristics (Continued)
October 2010
5
M9999-102210-A
Micrel, Inc.
MIC23031
Functional Characteristics
October 2010
6
M9999-102210-A
Micrel, Inc.
MIC23031
Functional Characteristics (Continued)
October 2010
7
M9999-102210-A
Micrel, Inc.
MIC23031
Functional Characteristics (Continued)
October 2010
8
M9999-102210-A
Micrel, Inc.
MIC23031
Functional Diagram
VIN
EN
CONTROL
LOGIC
Timer &
Softstart
UVLO
Gate
Drive
Reference
SW
Current
Limit
ERROR
COMPARATOR
ZERO 1
ISENSE
PGND
SNS
AGND
Simplified MIC23031 Fixed Functional Block Diagram
VIN
EN
CONTROL
LOGIC
Timer &
Softstart
UVLO
Gate
Drive
Reference
SW
Current
Limit
ERROR
COMPARATOR
ZERO 1
ISENSE
SNS
FB
GND
Simplified MIC23031 Adjustable Functional Block Diagram
October 2010
9
M9999-102210-A
Micrel, Inc.
MIC23031
Functional Description
AGND (Fixed Output Only)
The analog ground (AGND) is the ground path for the
biasing and control circuitry. The current loop for the
signal ground should be separate from the power ground
(PGND) loop. Refer to the layout recommendations for
more details.
VIN
The input supply (VIN) provides power to the internal
MOSFETs for the switch mode regulator along with the
internal control circuitry. The VIN operating range is 2.7V
to 5.5V so an input capacitor, with a minimum voltage
rating of 6.3V, is recommended. Due to the high
switching speed, a minimum 2.2µF bypass capacitor
placed close to VIN and the power ground (PGND) pin is
required. Refer to the layout recommendations for
details.
FB (Adjustable Output Only)
The feedback pin (FB) allows the regulated output
voltage to be set by applying an external resistor
network. The internal reference voltage is 0.62V and the
recommended value of R2 is 200kΩ. The output voltage
is calculated from the equation below.
EN
A logic high signal on the enable pin activates the output
voltage of the device. A logic low signal on the enable
pin deactivates the output and reduces supply current to
0.01µA. MIC23031 features built-in soft-start circuitry
that reduces in-rush current and prevents the output
voltage from overshooting at start up. Do not leave
floating.
⎛ R1
⎞
VOUT = 0.62V ⎜
+ 1⎟
200
kΩ
⎝
⎠
MIC23031
VIN
SW
The switch (SW) connects directly to one end of the
inductor and provides the current path during switching
cycles. The other end of the inductor is connected to the
load, SNS pin and output capacitor. Due to the high
speed switching on this pin, the switch node should be
routed away from sensitive nodes whenever possible.
SW
C1
EN
SNS
EN
VOUT
L1
R1
C2
FB
GND
R2
GND
GND
SNS
The sense (SNS) pin is connected to the output of the
device to provide feedback to the control circuitry. The
SNS connection should be placed close to the output
capacitor. Refer to the layout recommendations for more
details.
October 2010
VIN
Figure 1. MIC23031-AYMT Schematic
PGND / GND
The power ground pin is the ground path for the high
current in PWM mode. The current loop for the power
ground should be as small as possible and separate
from the analog ground (AGND) loop as applicable.
Refer to the layout recommendations for more details.
10
M9999-102210-A
Micrel, Inc.
MIC23031
The MIC23031 was designed for use with an inductance
range from 0.47µH to 4.7µH. Typically, a 1µH inductor is
recommended for a balance of transient response,
efficiency and output ripple. For faster transient
response, a 0.47µH inductor will yield the best result. For
lower output ripple, a 4.7µH inductor is recommended.
Maximum current ratings of the inductor are generally
given in two methods; permissible DC current and
saturation current. Permissible DC current can be rated
either for a 40°C temperature rise or a 10% to 20% loss
in inductance. Ensure the inductor selected can handle
the maximum operating current. When saturation current
is specified, make sure that there is enough margin so
that the peak current does not cause the inductor to
saturate. Peak current can be calculated as follows:
Application Information
The MIC23031 is a high-performance DC/DC step-down
regulator offering a small solution size. Supporting an
output current up to 400mA inside a tiny 1.6mm x 1.6mm
Thin MLF® package and requiring only three external
components, the MIC23031 meets today’s miniature
portable electronic device needs. Using the HyperLight
Load™ switching scheme, the MIC23031 is able to
maintain high efficiency throughout the entire load range
while providing ultra-fast load transient response. The
following sections provide additional device application
information.
Input Capacitor
A 2.2µF ceramic capacitor or greater should be placed
close to the VIN pin and PGND / GND pin for bypassing.
A TDK C1608X5R0J475K, size 0603, 4.7µF ceramic
capacitor is recommended based upon performance,
size and cost. A X5R or X7R temperature rating is
recommended for the input capacitor. Y5V temperature
rating capacitors, aside from losing most of their
capacitance over temperature, can also become
resistive at high frequencies. This reduces their ability to
filter out high-frequency noise.
⎡
⎛ 1 − VOUT /VIN ⎞⎤
⎟⎥
IPEAK = ⎢IOUT + VOUT ⎜⎜
⎟
2× f ×L
⎢⎣
⎠⎥⎦
⎝
As shown by the calculation above, the peak inductor
current is inversely proportional to the switching
frequency and the inductance; the lower the switching
frequency or the inductance the higher the peak current.
As input voltage increases, the peak current also
increases.
The size of the inductor depends on the requirements of
the application. Refer to Typical Application Circuit and
Bill of Materials for details.
DC resistance (DCR) is also important. While DCR is
inversely proportional to size, DCR can represent a
significant efficiency loss. Refer to the Efficiency
Considerations.
Output Capacitor
The MIC23031 was designed for use with a 2.2µF or
greater ceramic output capacitor. Increasing the output
capacitance will lower output ripple and improve load
transient response but could increase solution size or
cost. A low equivalent series resistance (ESR) ceramic
output capacitor such as the TDK C1608X5R0J475K,
size 0603, 4.7µF ceramic capacitor is recommended
based upon performance, size and cost. Both the X7R or
X5R temperature rating capacitors are recommended.
The Y5V and Z5U temperature rating capacitors are not
recommended due to their wide variation in capacitance
over temperature and increased resistance at high
frequencies.
Compensation
The MIC23031 is designed to be stable with a 0.47µH to
4.7µH inductor with a minimum of 2.2µF ceramic (X5R)
output capacitor.
Inductor Selection
When selecting an inductor, it is important to consider
the following factors (not necessarily in the order of
importance):
•
Inductance
•
Rated current value
•
Size requirements
•
DC resistance (DCR)
October 2010
Duty Cycle
The typical maximum duty cycle of the MIC23031 is
80%.
Efficiency Considerations
Efficiency is defined as the amount of useful output
power, divided by the amount of power supplied.
⎛V
×I
Efficiency % = ⎜ OUT OUT
⎜ V ×I
IN IN
⎝
11
⎞
⎟ × 100
⎟
⎠
M9999-102210-A
Micrel, Inc.
MIC23031
Maintaining high efficiency serves two purposes. It
reduces power dissipation in the power supply, reducing
the need for heat sinks and thermal design
considerations and it reduces consumption of current for
battery powered applications. Reduced current draw
from a battery increases the devices operating time and
is critical in hand held devices.
There are two types of losses in switching converters;
DC losses and switching losses. DC losses are simply
the power dissipation of I2R. Power is dissipated in the
high side switch during the on cycle. Power loss is equal
to the high side MOSFET RDSON multiplied by the Switch
Current squared. During the off cycle, the low side Nchannel MOSFET conducts, also dissipating power.
Device operating current also reduces efficiency. The
product of the quiescent (operating) current and the
supply voltage represents another DC loss. The current
required driving the gates on and off at a constant 4MHz
frequency and the switching transitions make up the
switching losses.
The DCR losses can be calculated as follows:
L Pd = IOUT2 × DCR
From that, the loss in efficiency due to inductor
resistance can be calculated as follows:
⎛V
×I
Efficiency % = ⎜ OUT OUT
⎜ V ×I
IN IN
⎝
⎞
⎟ × 100
⎟
⎠
Efficiency loss due to DCR is minimal at light loads and
gains significance as the load is increased. Inductor
selection becomes a trade-off between efficiency and
size in this case.
HyperLight Load™ Mode
MIC23031 uses a minimum on and off time proprietary
control loop (patented by Micrel). When the output
voltage falls below the regulation threshold, the error
comparator begins a switching cycle that turns the
PMOS on and keeps it on for the duration of the
minimum-on-time. This increases the output voltage. If
the output voltage is over the regulation threshold, then
the error comparator turns the PMOS off for a minimumoff-time until the output drops below the threshold. The
NMOS acts as an ideal rectifier that conducts when the
PMOS is off. Using a NMOS switch instead of a diode
allows for lower voltage drop across the switching device
when it is on. The asynchronous switching combination
between the PMOS and the NMOS allows the control
loop to work in discontinuous mode for light load
operations. In discontinuous mode, the MIC23031 works
in pulse frequency modulation (PFM) to regulate the
output. As the output current increases, the off-time
decreases, thus provides more energy to the output.
This switching scheme improves the efficiency of
MIC23031 during light load currents by only switching
when it is needed. As the load current increases, the
MIC23031 goes into continuous conduction mode (CCM)
and switches at a frequency centered at 4MHz. The
equation to calculate the load when the MIC23031 goes
into continuous conduction mode may be approximated
by the following formula:
Figure 2. MIC23031 Efficiency Curve
The figure above shows an efficiency curve. From no
load to 100mA, efficiency losses are dominated by
quiescent current losses, gate drive and transition
losses. By using the HyperLight Load™ mode, the
MIC23031 is able to maintain high efficiency at low
output currents.
Over 100mA, efficiency loss is dominated by MOSFET
RDSON and inductor losses. Higher input supply voltages
will increase the Gate-to-Source threshold on the
internal MOSFETs, thereby reducing the internal RDSON.
This improves efficiency by reducing DC losses in the
device. All but the inductor losses are inherent to the
device. In which case, inductor selection becomes
increasingly critical in efficiency calculations. As the
inductors are reduced in size, the DC resistance (DCR)
can become quite significant.
October 2010
Eq. 3
(
)
⎛ V - VOUT × D ⎞
⎟
ILOAD = ⎜⎜ IN
⎟
2L × f
⎝
⎠
12
M9999-102210-A
Micrel, Inc.
MIC23031
As shown in the previous equation, the load at which
MIC23031 transitions from HyperLight Load™ mode to
PWM mode is a function of the input voltage (VIN), output
voltage (VOUT), duty cycle (D), inductance (L) and
frequency (f). This is illustrated in the graph below. Since
the inductance range of MIC23031 is from 0.47µH to
4.7µH, the device may then be tailored to enter
HyperLight Load™ mode or PWM mode at a specific
load current by selecting the appropriate inductance. For
example, in Figure 3, when the inductance is 4.7µH the
MIC23031 will transition into PWM mode at a load of
approximately 4mA. Under the same condition, when the
inductance is 1µH, the MIC23031 will transition into
PWM mode at approximately 70mA.
Figure 3. MIC23031 SW Frequency vs. Output Current
October 2010
13
M9999-102210-A
Micrel, Inc.
MIC23031
MIC23031 Typical Application Circuit (Fixed 1.8V)
U1 MIC23031
VIN
2.7 to 5.5V
1
VIN
SW 2
EN
SNS 3
C1
EN
GND
VOUT
L1
C2
4
AGND
5
PGND
6
GND
Bill of Materials
Item
C1, C2
Part Number
C1608X5R0J475K
LQM21PN1R0M00
L1
(1)
TDK
Description
1µH, 0.8A, 190mΩ, L2mm x W1.25mm x H0.5mm
(2)
Murata
Murata
1µH, 1A, 60mΩ, L3.2mm x W2.5mm x H2.0mm
LQM31PN1R0M00
Murata(2)
1µH, 1.2A, 120mΩ, L3.2mm x W1.6mm x H0.95mm
LQM31PNR47M00
TDK
(1)
Murata(2)
MIPF2520D1R5
FDK(3)
MIC23031-xYMT
Micrel, Inc.(4)
Qty.
4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603
(2)
LQH32CN1R0M33
GLF251812T1R0M
U1
Manufacturer
2
1
1µH, 0.8A, 100mΩ, L2.5mm x W1.8mm x H1.35mm
0.47µH, 1.4A, 80mΩ, L3.2mm x W1.6mm x H0.85mm
1.5µH, 1.5A, 70mΩ, L2.5mm x W2mm x H1.0mm
4MHz 400mA Buck Regulator with HyperLight Load™ Mode
1
Notes:
1.
TDK: www.tdk.com.
2.
Murata: www.murata.com.
3.
FDK: www.fdk.co.jp.
4.
Micrel, Inc.: www.micrel.com.
October 2010
14
M9999-102210-A
Micrel, Inc.
MIC23031
MIC23031 Typical Application Circuit (Adjustable 1.8V)
U1 - MIC23031
VIN
1
SW 2
VIN
C1
EN
4
VOUT
L1
SNS 3
FB 5
EN
GND
6
GND
R1
383k
R2
200k
C2
GND
Bill of Materials
Item
C1, C2
R1
Part Number
C1608X5R0J475K
CRCW06033833FT1
R2
L1
(1)
TDK
(2)
Vishay
(2)
Description
2
383kΩ, 1%, Size 0603
1
1
CRCW06032003FT1
Vishay
200kΩ, 1%, Size 0603
Murata(3)
1µH, 0.8A, 190mΩ, L2mm x W1.25mm x H0.5mm
LQH32CN1R0M33
Murata(3)
1µH, 1A, 60mΩ, L3.2mm x W2.5mm x H2.0mm
LQM31PN1R0M00
(3)
Murata
1µH, 1.2A, 120mΩ, L3.2mm x W1.6mm x H0.95mm
GLF251812T1R0M
TDK(1)
1µH, 0.8A, 100mΩ, L2.5mm x W1.8mm x H1.35mm
LQM31PNR47M00
Murata(3)
MIC23031-AYMT
FDK
(4)
Micrel, Inc.(5)
Qty.
4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603
LQM21PN1R0M00
MIPF2520D1R5
U1
Manufacturer
1
0.47µH, 1.4A, 80mΩ, L3.2mm x W1.6mm x H0.85mm
1.5µH, 1.5A, 70mΩ, L2.5mm x W2mm x H1.0mm
4MHz 400mA Buck Regulator with HyperLight Load™ Mode
1
Notes:
1.
TDK: www.tdk.com.
2.
Vishay: www.vishay.com.
3.
Murata: www.murata.com.
4.
FDK: www.fdk.co.jp.
5.
Micrel, Inc.: www.micrel.com.
October 2010
15
M9999-102210-A
Micrel, Inc.
MIC23031
PCB Layout Recommendations (Fixed)
Fixed Top Layer
Fixed Bottom Layer
October 2010
16
M9999-102210-A
Micrel, Inc.
MIC23031
PCB Layout Recommendations (Adjustable)
Adjustable Top Layer
Adjustable Bottom Layer
October 2010
17
M9999-102210-A
Micrel, Inc.
MIC23031
Package Information
6-pin 1.6mm x 1.6mm Thin MLF® (MT)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2008 Micrel, Incorporated.
October 2010
18
M9999-102210-A
Similar pages