MIC4930YFL [MICREL]
Hyper Speed Control 3A Buck Regulator;
| 型号： | MIC4930YFL |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Hyper Speed Control 3A Buck Regulator 开关 |
| 文件： | 总17页 (文件大小：1128K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC4930
Hyper Speed Control™ 3A Buck Regulator
Features
General Description
Input voltage: 2.7V to 5.5V
3A output current
Up to 95% efficiency
Up to 3.3MHz operation
Safe start-up into a pre-biased output
Power Good output
Ultra-fast transient response
Low output voltage ripple
Low RDS(ON) integrated MOSFET switches
0.01µA shutdown current
Thermal shutdown and current limit protection
Output voltage as low as 0.7V
3mm × 4mm DFN-10L
The MIC4930 is a high-efficiency, 3A synchronous buck
regulator with ultra-fast transient response perfectly suited
for supplying processor core and I/O voltages from a 5V or
3.3V bus. The MIC4930 provides a switching frequency up
to 3.3MHz while achieving peak efficiencies up to 95%. An
additional benefit of high-frequency operation is very low
output ripple voltage throughout the entire load range with
the use of a small output capacitor. The MIC4930 is
designed for use with a very small inductor, down to 1µH,
and an output ceramic capacitor as small as 10µF without
the need for external ripple injection. A wide range of
output capacitor types and values can also be
accommodated.
The MIC4930 supports safe start-up into a pre-biased
output.
–40C to +125C junction temperature range
The MIC4930 is available in a 10-pin 3mm × 4mm DFN
package with an operating junction temperature range
from –40°C to +125°C. The MIC4930 is pin-to-pin
compatible with the 5A-rated MIC4950YFL.
Applications
DTVs
Set-top boxes
Printers
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
DVD players
Distributed power supplies
Typical Application
Hyper Speed Control is a trademark of Micrel, 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
Revision 1.1
March 20, 2014
Micrel, Inc.
MIC4930
Ordering Information
Part Number(1)
Top Mark
MIC4930
Temperature Range
Package(2)
Lead Finish
Pb-Free
MIC4930YFL
–40°C ≤ TJ ≤ +125°C
10-pin 3mm × 4mm DFN
Note:
1. Other options are available. Contact Micrel for details.
2. DFN is a GREEN, RoHS-compliant package. Lead finish is NiPdAu. Mold compound is Halogen free.
Pin Configuration
3mm × 4mm DFN (FL)
(Top View)
Pin Description
Pin Number
Pin Name
Pin Function
1, 2, EP
PGND
Power ground.
Power input voltage: Connect a 10µF ceramic capacitor between PVIN and PGND for input
decoupling. Pins 3 and 8 are internally connected inside the package.
3, 8
4
PVIN
AVIN
AGND
FB
Analog input voltage: Connect a 1µF ceramic capacitor between AVIN and AGND to decouple the
noise for the internal reference and error comparator.
Analog ground input: Connect to a quiet ground plane for best operation. Do not route power
switching currents on the AGND net. Connect AGND and PGND nets together at a single point.
5
Feedback (input): Connect an external divider between VOUT and AGND to program the output
voltage.
6
Power Good (output): Open-drain output. A pull-up resistor from this pin to a voltage source is
required to detect an output power-is-good condition.
7
PG
Enable (input): Logic high enables operation of the regulator. Logic low will shut down the device.
Do not leave floating.
9
EN
10
SW
Switch (output): Internal power MOSFET output switches.
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MIC4930
Absolute Maximum Ratings(3)
Operating Ratings(4)
PVIN, AVIN Supply Voltage (VIN).................... –0.3V to +6V
SW Output Switch Voltage (VSW). .....................–0.3V to VIN
EN, PG (VEN, VPG) .............................................–0.3V to VIN
FB Feedback Input Voltage (VFB)......................–0.3V to VIN
Storage Temperature (Ts).........................–65°C to +150°C
ESD Rating(5)........................................................2kV, HBM
Supply Voltage (VIN)..................................... +2.7V to +5.5V
Enable Input Voltage (VEN)..................................... 0V to VIN
Junction Temperature Range (TJ).......–40°C ≤ TJ ≤ +125°C
Thermal Resistance
DFN-10 (JA) ......................................................35°C/W
Electrical Characteristics(6)
VIN = VEN = 3.3V; L = 1.0µH; TA = 25°C, CIN = 10µH, COUT = 10µH unless otherwise specified.
Bold values indicate –40°C≤ TJ ≤ +85°C, unless otherwise noted.
Symbol
VIN
Parameter
Condition
Min.
2.7
Typ.
Max.
5.5
Units
V
Supply voltage range
Undervoltage lockout threshold
Undervoltage lockout hysteresis
Quiescent current
2.41
2.61
VUVLO
VUVLOH
IQ
(turn-on)
2.5
400
V
mV
mA
µA
V
2
2
IOUT = 0mA, FB >1.2 × VFB(Nominal)
VEN = 0V
0.8
ISD
Shutdown current
0.01
0.625
5.75
0.609
0.640
8
VFB
Feedback voltage
ILIMIT
Current limit
FB = 0.9V × VFB(Nominal)
3.5
A
VIN = 2.7V to 3.5V, VOUTNOM = 1.8V,
ILOAD = 20mA
LINEREG
Output voltage line regulation
1
0.3
1
%/V
%
VIN = 4.5V to 5.5V if VOUTNOM ≥2.5V,
ILOAD = 20mA
20mA < ILOAD < 500mA, VIN = 3.6V
if VOUTNOM < 2.5V
20mA < ILOAD < 500mA, VIN = 5.0V
if VOUTNOM ≥ 2.5V
LOADREG
Output voltage load regulation
PWM switch ON resistance
20mA < ILOAD < 3A, VIN = 3.6V
if VOUTNOM < 2.5V
%
20mA < ILOAD < 3mA, VIN = 5.0V
if VOUTNOM ≥ 2.5V
RDSON-P
RDSON-N
ISW = 1A P-Channel MOSFET
ISW = 1A N-Channel MOSFET
30
25
mΩ
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MIC4930
Electrical Characteristics Continued(6)
VIN = VEN = 3.3V; L = 1.0µH; TA = 25°C, CIN = 10µH, COUT = 10µH unless otherwise specified.
Bold values indicate –40°C≤ TJ ≤ +85°C, unless otherwise noted.
Symbol
Parameter
Condition
Min.
Typ.
665
1000
1120
176
500
0.8
Max.
Units
VIN = 4.5V, VFB = 0.5V
VIN = 3.0V, VFB = 0.5V
VIN = 2.7V, VFB = 0.5V
VIN = 3.0V, VFB = 0.5V
VOUT = 90% of VOUTNOM
Turn-on
tON
Maximum turn-on time
ns
tOFF
Minimum turn-off time
Soft-start time
ns
µs
V
tSOFT-ON
VEN
0.5
82
1.2
1
Enable threshold
IEN
Enable input current
Power Good threshold
Power Good hysteresis
Overtemperature shutdown
0.1
µA
%
94
VOUTPG
VOUTPGH
TSD
Rising
88
7
%
150
°C
Overtemperature shutdown
hysteresis
TSDH
20
°C
Notes:
3. Exceeding the absolute maximum ratings may damage the device.
4. The device is not guaranteed to function outside its operating ratings.
5. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.
6. Specification for packaged product only.
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MIC4930
Typical Characteristics
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MIC4930
Typical Characteristics (Continued)
Switching Frequency
vs. Temperature
3.0
2.8
2.6
2.4
2.2
2.0
VIN = 3.3V
VOUT = 1.8V
IOUT = 0A
-50
-20
10
40
70
100
130
TEMPERATURE (°C)
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MIC4930
Functional Characteristics
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MIC4930
Functional Characteristics (Continued)
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MIC4930
Functional Block Diagram
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MIC4930
FB
Functional Description
To program the output voltage, an external resistive
divider network is connected to this pin from the output
voltage to AGND, as shown in the Typical Application
circuit on page 1, and is compared to the internal 0.625V
reference within the regulation loop. The following
formula is used to program the output voltage.
PVIN
The power input (PVIN) pin provides power to the internal
MOSFETs for the switch mode regulator section of the
MIC4930. The input supply operating range is from 2.7V
to 5.5V. A low-ESR ceramic capacitor of at least 10µF is
required to bypass from PVIN to (power) GND. See the
Application Information section for further details.
R1
R2
VOUT VREF 1
Eq. 1
AVIN
The analog power input (AVIN) pin provides power to the
internal control and analog supply circuitry. Careful layout
should be considered to ensure that high-frequency
switching noise caused by PVIN is reduced before
reaching AVIN. Always place a 1µF minimum ceramic
capacitor very close to the IC between the AVIN and
AGND pins. For additional high-frequency switching
noise attenuation, RC filtering can be used (R = 10Ω).
Recommended feedback resistor values:
VOUT
1.0V
1.2V
1.5V
1.8V
2.5V
3.3V
R1
R2
120k
274k
316k
301k
316k
309k
180k
294k
226k
160k
105k
71.5k
EN
A logic high signal on the enable (EN) pin activates the
output of the switch. A logic low on EN deactivates the
output and reduces the supply current to a nominal
0.01µA. Do not leave this pin floating.
The feed-forward capacitor (CF in the Typical Application
diagram) is typically in the range of 22pF to 39pF. The
MIC4930 features an internal ripple injection network,
whose current is injected into the FB node and integrated
by CF. Thus, the waveform at FB is approximately a
triangular ripple. The size of CF dictates the amount of
ripple amplitude at the FB node. Smaller values of CF
yield higher FB ripple amplitudes and better stability, but
also somewhat degrade line regulation and transient
response.
SW
The switch (SW) pin connects directly to one side of the
inductor and provides the current path during switching
cycles. The other end of the inductor is connected to the
load and output capacitor. Due to the high speed
switching on this pin, the switch node should be routed
away from sensitive nodes whenever possible to avoid
unwanted injection of noise.
PGND
The power ground (PGND) pin is the ground return
terminal for the high current in the switching node SW.
The current loop for the PGND should be as short as
possible and kept separate from the AGND net whenever
applicable.
Hyper Speed Control™
MIC4930 uses an ON- and OFF-time proprietary ripple-
based control loop that features three different timers:
Minimum ON Time
Maximum ON Time
Minimum OFF Time
AGND
The analog ground (AGND) pin is the ground return
terminal 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 further details.
When the required duty cycle is very low, the required
OFF time is typically far from the minimum OFF time limit
(about 176ns typically). In this case, the MIC4930
operates by delivering a determined ON time at each
switching cycle, depending on the input voltage. A new
ON time is invoked by the error comparator when the FB
voltage falls below the regulation threshold. In this mode,
the MIC4930 operates as an adaptive constant-ON-time
ripple controller with nearly constant switching frequency.
Regulation takes place by controlling the valley of the FB
ripple waveform.
PG
The power-is-good (PG) pin is an open-drain output that
indicates logic high when the output voltage is typically
above 88% of its steady-state voltage. A pull-up resistor
of 10kΩ or greater should be connected from PG to
VOUT.
When higher duty cycles are required, regulation can no
longer be maintained by decreasing the OFF time below
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MIC4930
the minimum OFF time limit. When this limit is reached,
the OFF time is no longer reduced, and the MIC4930
smoothly transitions to an ON-time modulation mode. In
the ON-time modulation region, frequency reduces with
the increase of the required ON-time / duty cycle, and
regulation finally takes place on the peak of the FB ripple
waveform.
Note that because of the shift of the regulation threshold
between different modes, line regulation might suffer
when the input voltage and/or duty cycle variations force
the MIC4930 to switch form one regulation mode to the
other. In applications where wide input voltage variations
are expected, ensure that the line regulation is adequate
for the intended application.
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MIC4930
Also pay attention to the inductor saturation characteristic
in current limit. The inductor should not heavily saturate
even in current limit operation, otherwise the current
might instantaneously run away and reach potentially
destructive levels. Typically, ferrite-core inductors exhibit
an abrupt saturation characteristic, while powedered-iron
Application Information
The MIC4930 is a highly efficient, 3A synchronous buck
regulator ideally suited for supplying processor core and
I/O voltages from a 5V or 3.3V bus.
Input Capacitor
or composite inductors have
characteristic.
a
soft-saturation
A 10µF ceramic capacitor or greater should be placed
close to the PVIN pin and PGND pin for bypassing. A
X5R or X7R temperature rating is recommended for the
input capacitor. Take into account C vs. bias effect in
order to estimate the effective capacitance and the input
ripple at the VIN voltage.
Peak current can be calculated by using Equation 2.
1 VOUT /V
IPEAK I
OUT
VOUT
IN
Eq. 2
2 f L
Output Capacitor
The MIC4930 is designed for use with a 10µF or greater
ceramic output capacitor. Increasing the output
capacitance will lower output ripple and improve load
transient response. A low equivalent series resistance
(ESR) ceramic output capacitor is recommended based
upon performance, size, and cost. Ceramic capacitors
with X5R or X7R temperature ratings are recommended.
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 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 the typical application circuit and
Bill of Materials for details.
Inductor Selection
When selecting an inductor, it is important to consider the
following factors:
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 subsection.
Inductance
Rated current value
Size requirements
DC resistance (DCR)
Core losses
Efficiency Considerations
Efficiency is defined as the amount of useful output
power, divided by the amount of power supplied (see
Typical Characteristics section).
The MIC4930 is designed for use with a 1µH to 2.2µH
inductor. For faster transient response, a 1µH inductor
will yield the best result. For lower output ripple, a 2.2µH
inductor is recommended.
VOUT IOUT
VIN IIN
Efficiency%
100
Eq. 3
Inductor current ratings are generally given in two
methods: permissible DC current, and saturation current.
Permissible DC current can be rated for a 20°C to 40°C
temperature rise. Saturation current can be rated for a
10% to 30% loss in inductance. Ensure that the nominal
current of the application is well within the permissible DC
current ratings of the inductor, also depending on the
allowed temperature rise. Note that the inductor
permissible DC current rating typically does not include
inductor core losses. These are a very important
contribution to the total inductor core loss and
temperature increase in high-frequency DC-to-DC
converters, since core losses increase with at least the
square of the excitation frequency. For more accurate
core loss estimation, it is recommended to refer to
manufacturers’ datasheets or websites.
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 N-channel
MOSFET conducts, also dissipating power. The 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 high frequency and the switching
transitions make up the switching losses.
At the higher currents for which the MIC4930 is designed,
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 that case,
When saturation current is specified, make sure that
there is enough design margin, so that the peak current
does not cause the inductor to enter saturation.
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MIC4930
inductor selection becomes increasingly critical in
efficiency calculations. As the inductors are reduced in
size, the DC resistance (DCR) can become quite
significant. The DCR losses can be calculated as in:
The injected ripple is
1
ΔVFB(pp) VIN Kdiv D(1-D)
Eq. 6
PDCR = IOUT2 x DCR
Eq. 4
fSW
with Kdiv given by
From that, the loss in efficiency due to inductor DCR and
core losses (PCORE) can be calculated as in Equation 5.
VOUT IOUT
R1//R2
Efficiency Loss (%) 1
100
Kdiv
Eq. 7
VOUT IOUT PDCR PCORE
Rinj R1//R2
Eq. 5
and
External Ripple Injection
VIN = Power stage input voltage
D = VOUT/VIN = Duty cycle
fSW = Switching frequency
τ = (R1//R2//Rinj) × CF
The MIC4930 control loop is ripple-based, and relies on
an internal ripple injection network to generate enough
ripple amplitude at the FB pin when negligible output
voltage ripple is present. The internal ripple injection
network is typically sufficient when recommended R1-R2
and CF values are used. The FB ripple amplitude should
fall in the 20mV to 100mV range.
In Equations 6 and 7, it is assumed that the time constant
associated with CF must be greater than the switching
period.
If significantly lower divider resistors and/or higher CF
values are used, the amount of internal ripple injection
may not be sufficient for stable operation. In this case,
external ripple injection is needed. This is accomplished
by connecting a series Rinj-Cinj circuit between the SW
and the FB pins, as shown in Figure 1.
1
T
1
Eq. 8
fSW
Figure 1. External Ripple Injection
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MIC4930
Evaluation Board Circuit
Bill of Materials
Item
Part Number
Manufacturer
TDK(7)
Description
Qty.
C2012X5R1A106M125AB
GRM219R61A106ME44
C1608C0G1H220J080AA
GRM1885C1H220JA01
C1608X5R1A105M080AC
GRM185R61A105ME26
C1,
C2
Ceramic capacitor, 10µF, 10V X5R, Size 0805
2
Murata(8)
TDK
C3
C4
Ceramic capacitor, 22pF, 50V, C0G, Size 0603
Ceramic capacitor, 1µF, 10V, X5R, Size 0603
1
1
Murata
TDK
Murata
C5
C6
C7
DNP, Size 0603
0
0
0
DNP, Size 1210
DNP, Radial, 8mm diameter polarized capacitor
1µH, 6.4A, 7.3mΩ, L7.3mm × W6.8mm × H3.2mm
1µH, 4.5A, 11mΩ, L6.2mm × W5.9mm × H4.5mm
1µH, 6.5A, 13mΩ, L6.8mm × W6.8mm × H4.5mm
RLF7030T-1R0N6R4
CLF6045T-1R0N
TDK
TDK
TDK
L1
1
VLP6045LT-1R0N
CDRH5D28RH125NP-
1R0PC
Sumida(9)
1µH, 4.1A, 13.5mΩ, L6.3mm × W6.2mm × H3.0mm
R1
R2
CRCW06033013FK
CRCW06031603FK
Vishay(10)
Vishay
Resistor, 301kΩ, Size0603
1
1
0
1
1
1
1
1
Resistor, 160kΩ, Size 0603
R3
DNP, Size 0603
R4
CRCW060310R0FK
CRCW06031002FK
CRCW06031003FK
CRCW060349R9FK
MIC4930YFL
Vishay
Vishay
Resistor, 10Ω, Size 0603
R5
Resistor, 10kΩ, Size 0603
R6
Vishay
Resistor, 100kΩ, Size 0603
R7
Vishay
Micrel, Inc.(11)
Resistor, 49.9Ω, Size 0603, for monitoring SW node only
Hyper Speed Control™ 3A Buck Regulator
U1
Notes:
7. TDK: www.tdk.com.
8. Murata: www.murata.com.
9. Sumida: www.sumida.com.
10. Vishay: www.vishay.com.
11. Micrel, Inc.: www.micrel.com.
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PCB Layout Recommendations
Top Layer
Bottom Layer
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MIC4930
Package Information(12)
10-Pin DFN 3mm x 4mm (FL)
Note:
12. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.
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MIC4930
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.
© 2014 Micrel, Incorporated.
Revision 1.1
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