MIC33050-GYHL [MICREL]
4MHz Internal Inductor PWM Buck Regulator with HyperLight Load⑩; 4MHz的内部电感的PWM降压型稳压器的HyperLight Load⑩型号: | MIC33050-GYHL |
厂家: | MICREL SEMICONDUCTOR |
描述: | 4MHz Internal Inductor PWM Buck Regulator with HyperLight Load⑩ |
文件: | 总13页 (文件大小:587K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
MIC33050
4MHz Internal Inductor PWM Buck
Regulator with HyperLight Load™
General Description
Features
The Micrel MIC33050 is a high efficiency 500mA PWM
synchronous buck (step-down) regulator with internal
inductor featuring HyperLight Load™, a patent-pending
switching scheme that offers best-in-class light load
efficiency and transient performance while providing very
small external components and low output ripple at all
loads.
• Input voltage: 2.7V to 5.5V
• 500mA output current
• Fixed output voltage options from 0.72V to 2.5V
• No external inductor required
HyperLight Load™
• Ultra fast transient response
• 20µA typical quiescent current
• 4MHz in PWM in constant current mode
• Low voltage output ripple
The MIC33050 also has a very low typical quiescent
current draw of 20µA and can achieve over 83% efficiency
even at 1mA.
–
25mVpp in HyperLight Load™ mode
–
3mV output voltage ripple in full PWM mode
In contrast to traditional light load schemes, the HyperLight
Load™ architecture does need not trade off control speed
to obtain low standby currents and in doing so, the device
only needs a small output capacitor to absorb the load
transient as the powered device goes from light load to full
load.
• >93% efficiency
• >83% at 1mA
• Micropower shutdown
• 3mm x 3mm MLF®-12L
• –40°C to +125°C junction temperature range
At higher loads, the MIC33050 provides a constant
switching frequency of greater than 4MHz while providing
peak efficiencies greater than 93%.
Applications
The MIC33050 comes in fixed output voltage options from
0.72V to 2.5V thereby eliminating external feedback
components.
• Cellular phones
• Digital cameras
• Portable media players
• Wireless LAN cards
• WiFi/WiMax/WiBro modules
• USB Powered Devices
The MIC33050 is available in an 12-pin 3mm x 3mm MLF®
with a junction operating range of –40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
____________________________________________________________________________________________________________
Typical Application
HyperLight Load is a trademark of Micrel, Inc.
MLF and MicroLeadFrame 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
M9999-100407-A
October 2007
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Micrel, Inc.
MIC33050
Ordering Information
Part Number
MIC33050-4YHL
MIC33050-GYHL
Note:
Voltage
1.2V
Temperature Range
–40° to +125°C
Package
Lead Finish
Pb-Free
12-Pin 3mm x 3mm MLF®
12-Pin 3mm x 3mm MLF®
1.8V
–40° to +125°C
Pb-Free
1. Other voltage options available. Contact Micrel for details.
Pin Configuration
12-Pin 3mm x 3mm MLF® (ML)
Pin Description
Pin Number
Pin Name
VIN
Pin Function
Supply Voltage (Input): Requires bypass capacitor-to-GND.
1
9
EN
Enable (Input): Logic low will shut down the device, reducing the quiescent
current to less than 4µA.
10
SNS
Input to the error amplifier, connect to the external resistor divider network to set
the output voltage. For fixed output voltages connect to VOUT and an internal
resistor network sets the output voltage.
11
2
CFF
PGND
AGND
SW
Feed forward Capacitor connected to Out sense pin
Power Ground
12
Analog ground
3,4,5,6
7,8
Switch (Output): Internal power MOSFET output switches.
Output after the internal inductor
OUT
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Micrel, Inc.
MIC33050
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN).........................................................6V
Output Switch Voltage (VSW)............................................6V
Output Switch Current (ISW)..............................................2A
Logic Input Voltage (VEN) ..................................–0.3V to VIN
Storage Temperature Range (Ts)..............–65°C to +150°C
ESD Rating(3)..................................................................3kV
Supply Voltage (VIN)......................................... 2.7V to 5.5V
Logic Input Voltage (VEN)…………………………-0.3V to VIN
Junction Temperature (TJ) ..................–40°C ≤ TJ ≤ +125°C
Thermal Resistance
3mm x 3mm MLF®-12 (θJA)................................60°C/W
Electrical Characteristics(4)
TA = 25°C with VIN = VEN = 3.6V; CFF = 560pF; COUT = 4.7µF; IOUT = 20mA unless otherwise specified.
Bold values indicate –40°C< TJ < +125°C.
Parameter
Condition
Min
2.7
Typ
Max
5.5
Units
V
Supply Voltage Range
Under-Voltage Lockout Threshold
UVLO Hysteresis
(turn-on)
2.45
2.55
100
2.65
V
mV
Quiescent Current,
Hyper LL mode
IOUT = 0mA , VSNS > 1.2*VOUT nominal
20
32
µA
Shutdown Current
VIN = 5.5V; VEN = 0V;
0.01
4
µA
%
Output Voltage Accuracy
Current Limit in PWM Mode
Output Voltage Line Regulation
Output Voltage Load Regulation
Maximum Duty Cycle
VIN = 3.0V, ILOAD = 20mA
SNS = 0.9*VNOM
–2.5
0.65
+2.5
1.7
1
A
VIN = 3.0V to 5.5V, ILOAD = 20mA
20mA < ILOAD < 500mA,
0.5
0.3
89
%/V
%
80
%
SNS ≤ VNOM
ISW = 100mA PMOS
ISW = -100mA NMOS
ILOAD = 120mA
0.45
0.5
Ω
Ω
PWM Switch ON-Resistance
Frequency
3.4
0.5
4
4.6
1.2
2
MHz
µs
Soft Start Time
VOUT = 90%
(turn-on)
650
0.8
35
Enable Threshold
Enable Hysteresis
Enable Input Current
Over-temperature Shutdown
V
mV
µA
°C
0.1
165
Over-temperature Shutdown
Hysteresis
20
°C
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.
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October 2007
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Micrel, Inc.
MIC33050
Typical Characteristics
Quiescent Current
vs. Temperature
Switching Frequency
vs. Temperature
Quiescent Current
vs. Input Voltage
40
5.5
5.0
4.5
4.0
3.5
3.0
2.5
50
45
40
35
30
25
20
15
10
5
30
20
10
V
V
= 3.6V
IN
V
= 1.8V
OUT
= 1.8V
V
V
= 3.6V
= 1.8V
OUT
IN
OUT
No Load
Load = 150mA
0
0
2.7 3.2 3.7 4.2 4.7 5.2
INPUT VOLTAGE (V)
20 40 60 80
TEMPERATURE (°C)
20 40 60 80
TEMPERATURE (°C)
Feedback Voltage
vs. Temperature
Output Voltage
vs. Temperature
Switching Frequency
vs. Input Voltage
0.80
1.90
1.85
1.80
1.75
1.70
5.5
5.0
4.5
4.0
3.5
3.0
2.5
0.78
0.76
0.74
0.72
0.70
0.68
0.66
0.64
0.62
0.60
V
V
= 3.6V
V
V
= 3.6V
IN
IN
V
OUT
= 1.8V
= 1.8V
= 1.8V
OUT
OUT
Load = 150mA
No Load
No Load
2.7 3.2 3.7 4.2 4.7 5.2
INPUT VOLTAGE (V)
20 40 60 80
TEMPERATURE (°C)
20 40 60 80
TEMPERATURE (°C)
Output Voltage
vs. Input Voltage
Output Voltage
vs. Load
1.90
1.90
1.85
1.80
1.75
1.70
1.85
1.80
1.75
1.70
V
IN
= 3.6V
Load = 20mA
2.7 3.2 3.7 4.2 4.7 5.2
INPUT VOLTAGE (V)
200 300
LOAD (mA)
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Micrel, Inc.
MIC33050
Functional Characteristics
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Micrel, Inc.
MIC33050
Functional Characteristics (continued)
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Micrel, Inc.
MIC33050
Functional Diagram
MIC33050 Simplified Block Diagram
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Micrel, Inc.
MIC33050
CFF
Functional Description
The CFF pin is connected to the SNS pin of MIC33050
with a feed-forward capacitor of 560pF. The CFF pin itself
is compared with the internal reference voltage (VREF) of
the device and provides the control path to control the
output. VREF is equal to 0.72V. The CFF pin is sensitive to
noise and should be place away from the SW pin. Refer to
the layout recommendations for details.
VIN
VIN provides power to the MOSFETs for the switch mode
regulator section and to the analog supply circuitry. Due to
the high switching speeds, it is recommended that a 2.2µF
or greater capacitor be placed close to VIN and the power
ground (PGND) pin for bypassing. Refer to the layout
recommendations for details.
PGND
EN
Power ground (PGND) is the ground path for the high
current PWM mode. The current loop for the power ground
should be as small as possible and separate from the
Analog ground (AGND) loop. Refer to the layout
recommendations for more details.
The enable pin (EN) controls the on and off state of the
device. A high logic on the enable pin activates the
regulator, while a low logic deactivates it. MIC33050
features built-in soft-start circuitry that reduces in-rush
current and prevents the output voltage from overshooting
at start up.
AGND
Signal 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.
SW
The switch (SW) pin connects directly to the inductor and
provides the switching current necessary to operate in
PWM mode. Due to the high speed switching on this pin,
the switch node should be routed away from sensitive
nodes such as the CFF pin.
OUT
The output pin (OUT) is the output voltage pin following
the internal inductor of the device. Connect an output filter
capacitor equal to 2.2µF or greater to this pin.
SNS
The SNS pin is needed to sense the output voltage at the
output filter capacitor. In order for the control loop to
monitor the output voltage accurately it is good practice to
sense the output voltage at the positive side the output
filter capacitor where voltage ripple is smallest.
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October 2007
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Micrel, Inc.
MIC33050
Applications Information
Input Capacitor
A minimum of 2.2µF ceramic capacitor should be placed
close to the VIN pin and PGND pin for bypassing. X5R or
X7R dielectrics are recommended for the input capacitor.
Y5V dielectrics, aside from losing most of their
capacitance over temperature, they also become resistive
at high frequencies. This reduces their ability to filter out
high frequency noise.
Output Capacitor
The MIC33050 was designed for use with a 2.2µF or
greater ceramic output capacitor. A low equivalent series
resistance (ESR) ceramic output capacitor either X7R or
X5R is recommended. Y5V and Z5U dielectric capacitors,
aside from the undesirable effect of their wide variation in
capacitance over temperature, become resistive at high
frequencies.
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 MIC33050 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. The DCR losses can be calculated as
follows;
Compensation
The MIC33050 is designed to be stable with an internal
inductor with a minimum of 2.2µF ceramic (X5R) output
capacitor.
Efficiency Considerations
Efficiency is defined as the amount of useful output power,
divided by the amount of power supplied.
⎛
⎞
VOUT ×IOUT
VIN ×IIN
⎜
⎜
⎟
⎟
Efficiency_% =
×100
L_Pd = IOUT2 × DCR
⎝
⎠
From that, the loss in efficiency due to inductor resistance
can be calculated as follows;
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
⎡
⎤
⎥
⎛
⎜
⎜
⎝
⎞
⎟
⎟
⎠
VOUT ×IOUT
VOUT ×IOUT + L_Pd
Efficiency_Loss = 1−
×100
⎢
⎢
⎣
⎥
⎦
applications. Reduced current draw from
a battery
increases the devices operating time and is critical in hand
held devices.
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.
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
Current2. During the off cycle, the low side N-channel
MOSFET conducts, also dissipating power. Device
operating current also reduces efficiency. The product of
the quiescent (operating) current and the supply voltage is
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.
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October 2007
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Micrel, Inc.
MIC33050
HyperLight Load™ Mode
pulse frequency modulation (PFM) to regulate the output.
As the output current increases, the switching frequency
increases. This improves the efficiency of the MIC33050
during light load currents. As the load current increases,
the MIC33050 goes into continuous conduction mode
(CCM) at a constant frequency of 4MHz. The equation to
calculate the load when the MIC33050 goes into
continuous conduction mode may be approximated by the
following formula:
The MIC33050 uses a minimum on and off time
proprietary control loop. 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. When
the output voltage is over the regulation threshold, the
error comparator turns the PMOS off for a minimum-off-
time. 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, MIC33050 works in
(V − VOUT ) × D
⎛
⎜
⎞
⎟
IN
ILOAD
=
2L × f
⎝
⎠
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October 2007
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Micrel, Inc.
MIC33050
MIC33050 Typical Application Circuit
Bill of Materials
Item
C1, C2
C3
Part Number
C1608X5R0J476K
C1005X5R0J476K
MIC33050-4YHL
MIC33050-GYHL
Manufacturer
TDK(1)
Description
Qty
2
4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603
560pF Ceramic Capacitor, 6.3V, X5R, Size 0402
Murata(2)
1
U1
Micrel, Inc. (4)
4MHz PWM Buck Regulator with HyperLight Load Mode
1
Notes:
1. TDK: www.tdk.com
2. Murata: www.murata.com
3. Micrel, Inc: www.micrel.com
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October 2007
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Micrel, Inc.
MIC33050
PCB Layout Recommendations
Top Layer
Bottom Layer
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Micrel, Inc.
MIC33050
Package Information
12-Pin 3mm x 3mm MLF® (ML)
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
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
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.
© 2007 Micrel, Incorporated.
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