MIC24085-BYMLTR [MICROCHIP]
Switching Regulator/Controller, Current-mode, 3A, 1100kHz Switching Freq-Max, PQCC16;
| 型号： | MIC24085-BYMLTR |
| 厂家： | 
MICROCHIP |
| 描述： | Switching Regulator/Controller, Current-mode, 3A, 1100kHz Switching Freq-Max, PQCC16 |
| 文件： | 总16页 (文件大小：1619K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC24085
18V, 3A, 1MHz, High-Performance,
Integrated FET Buck Regulator
in Tiny 3mm × 3mm QFN
Features
General Description
• Input voltage range 4.5V to 18V
• 3A output current
• 1MHz switching frequency
• 0.9V reference voltage with ±1.5% accuracy
• Fixed output voltages are available at:
1.5V/1.8V/2.5V/3.3V/5V
Micrel’s MIC24085 is a constant-frequency, current-mode
PWM buck regulator with integrated switchers. The
MIC24085 is targeted for cost-sensitive and high-
performance applications.
The MIC24085 operates over a supply range of 4.5V to
18V at a fixed 1MHz switching frequency and can be used
to provide up to 3A of output current. The output voltage is
adjustable down to 0.9V.
• Peak current-mode PWM with internal compensation
• PFM mode for light load efficiency
• 10µA typical shutdown current
• 4ms internal soft start
• Cycle-by-cycle current limit with frequency foldback
• Output overvoltage protection
The MIC24085 provides the features of low standby
current at 10µA, device enable, input undervoltage lockout,
and output voltage monitoring. The part also provides fault
protections of overcurrent and overtemperature.
The MIC24085 is available in a 16-pin 3mm × 3mm QFN
package with a junction operating range from –40°C to
+125°C.
• Enable input/power-good (PG) output
• Thermal-shutdown protection
• –40°C to +125°C junction temperature range
• Available in 16-pin 3mm × 3mm QFN package
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Applications
• Camera, set-top box, gateways, and routers
• Networking/telecom infrastructure
• Printers, scanners, graphic cards, and video cards
Typical Applications
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
October 22, 2013
Micrel, Inc.
MIC24085
Ordering Information
Part Number
Output Voltage
Junction Temperature Range
Package
Lead Finish
MIC24085AYML
MIC24085BYML
MIC24085CYML
MIC24085DYML
MIC24085EYML
MIC24085FYML
ADJ
1.5V
1.8V
2.5V
3.3V
5V
16-Pin 3mm x 3mm QFN
Pb-Free
–40°C to +125°C
Pin Configuration
16-Pin 3mm × 3mm QFN (ML)
(Top View)
Pin Description
Pin Number
Pin Name
Pin Function
Switch Node (Output): Power stage output. Connect an inductor to this pin.
1, 12, 13, 16
SW
Supply Voltage (for control circuit and power stage): A ceramic input capacitor between VCC and
the power ground (PGND) is required.
2, 3, 11
4
VCC
GND
Analog Ground: GND is the ground path of the control circuitry.
Feedback (Input): Input to the error amplifier of the PWM controller. The FB pin is regulated to
0.9V. A resistor divider connecting the feedback to the output is used to adjust the desired output
voltage.
5
FB
6, 7
8
NC
PG
No connection.
Power Good (Output): Open drain output, which needs a pull-up. The PG pin turns logic high when
the converter output voltage is regulated in the range from 93% to 103% of the setting.
Enable (Input): An accurate Enable with hysteresis is provided. High = enable, Low = shutdown.
Enable has an internal pull-up to ensure a stable state if this pin is not connected.
9
EN
Boost (Output): Bootstrapped voltage to the high-side N-channel MOSFET. A boost capacitor of
0.1μF is connected between the BST pin and the SW pin.
10
BST
14,15
EP
PGND
ePAD
Power Ground: PGND is the ground path for the power stage.
Exposed Pad. It must be connected to PGND on the PCB.
Revision 1.1
October 22, 2013
2
Micrel, Inc.
MIC24085
Operating Ratings(2)
Absolute Maximum Ratings(1)
Supply Voltage (VVCC) ....................................... 4.5V to 18V
Output Current ................................................................3A
Junction Temperature (TJ) ........................−40°C to +125°C
Junction Thermal Resistance
VVCC to PGND................................................ −0.3V to +20V
VSW to PGND................................................. −0.3V to +20V
VEN, VFB, VPG, to GND..................................... −0.3V to + 6V
V
V
BST to VSW ..................................................... −0.3V to + 6V
BST to PGND................................................ −0.3V to +26V
MLF-16 (θJA) .....................................................68°C/W
MLF-16 (θJC) ....................................................7.5°C/W
PGND to GND............................................. −0.3V to + 0.3V
Junction Temperature ..............................................+150°C
Storage Temperature (TS).........................−65°C to +150°C
Lead Temperature (soldering, 10sec)........................ 260°C
ESD Rating(3)..................................................................2kV
Electrical Characteristics(4)
VVCC = 12V; TA = 25°C, unless noted. Bold values indicate −40°C ≤ TJ ≤ +125°C.
Parameter
Condition
Min.
4.5
Typ.
Max.
Units
Power Supply Input
VCC Input Voltage Range
Quiescent Supply Current
Shutdown Supply Current
VCC UVLO Threshold
VCC UVLO Hysteresis
Reference (MIC24085AYML)
Feedback Reference Voltage
FB Bias Current
18
V
mA
µA
V
No Switching, VFB = 1.5V
VEN = 0V
2.3
5
10
4.5
4.3
650
mV
0.886
0.914
500
0.9
50
4
V
nA
ms
%
-40°C ≤ TJ ≤ +125°C (±1.5%)
VFB = 0.6V
Soft-Start Time
Load Regulation
IOUT = 100mA to 3A
VVCC = 4.5V to 18V
0.5
0.5
Line Regulation
%
Enable Control
2.2
EN Logic Level High
EN Logic Level Low
EN Hysteresis
V
V
0.8
1.1
480
3.5
mV
VEN = 5V
VEN = 0V
EN Bias Current
µA
-1.5
PWM
0.9
Switching Frequency
Foldback Switching Frequency
Maximum Duty Cycle
Minimum Duty Cycle
Notes:
VFB = 0.9V
1.0
250
97
0
MHz
kHz
%
VFB < 60% × 0.9V
VFB = 0V, 1MHz
VFB = 1V
%
1. Exceeding the absolute maximum ratings may damage the device.
2. The device is not guaranteed to function outside its operating ratings.
3. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.
4. Specification for packaged product only.
Revision 1.1
October 22, 2013
3
Micrel, Inc.
MIC24085
Electrical Characteristics(4) (Continued)
VVCC = 12V; TA = 25°C, unless noted. Bold values indicate −40°C ≤ TJ ≤ +125°C.
Parameter
Condition
Min.
Typ.
Max.
Units
Internal MOSFET
High Side On-Resistance
Low Side On-Resistance
Overcurrent Protection
Current-Limit Threshold
Power Good
ISW = 1A
ISW = 1A
135
90
mΩ
mΩ
3.4
91
4.4
95
VFB = 0.9V
3.8
A
Power Good Threshold Voltage
Power Good Hysteresis
Power Good Low Voltage
Sweep VFB from Low-to-High
Sweep VFB from High-to-Low
VFB < 90% x VNOM, IPG = -0.3mA
93
1.5
50
%VOUT
%VOUT
mV
100
12
PG recovery after power
restoration
Power Good Recovery Hold Time
9
11
ms
Thermal Protection
Overtemperature Shutdown
Overtemperature Shutdown Hysteresis
TJ Rising
170
10
°C
°C
Revision 1.1
October 22, 2013
4
Micrel, Inc.
MIC24085
Typical Characteristics
TJ = −40°C to +125°C, VCC = 12V (unless otherwise noted).
Revision 1.1
October 22, 2013
5
Micrel, Inc.
MIC24085
Typical Characteristics (Continued)
TJ = −40°C to +125°C, VCC = 12V (unless otherwise noted).
Revision 1.1
October 22, 2013
6
Micrel, Inc.
MIC24085
Functional Characteristics
TJ = −40°C to +125°C, VCC = 12V (unless otherwise noted).
Revision 1.1
October 22, 2013
7
Micrel, Inc.
MIC24085
Functional Diagram
Revision 1.1
October 22, 2013
8
Micrel, Inc.
MIC24085
Power Good (PG)
Functional Description
Power good (PG) is an open drain output pin. A 10kΩ
resistor to VOUT is required for pull-up. The PG pin turns
low if the output voltage is below 93% of the reference
voltage (0.9V). After VOUT fault and recovery, PG is held
low for a typical duration of 11ms. See the Electrical
Characteristics table for additional information.
Micrel’s MIC24085 is an 18V, 3A, 1MHz buck regulator
with integrated MOSFETSs for low-cost high-
performance applications. The MIC24085 provides basic
features including enable, power good, internal soft-start,
current-limit, and overtemperature protections.
VCC Supply Voltage and UVLO
The MIC24085 is held in the off state until VCC reaches
the UVLO threshold, which has a 650mV hysteresis. A
ceramic capacitor from VCC to PGND is recommended
for clean operation.
Enable and Soft-Start
When the MIC24085 is enabled, the reference voltage is
controlled to ramp-up from 0V to 0.9V in approximately
4ms. During the soft-start, the current limit is enabled to
protect the device in case of a short circuit present at the
output.
Peak Current-Mode PWM
To achieve fast transient response, the peak current-
mode PWM control is employed in the MIC24085. As
illustrated in the Functional Diagram, the high-side
MOSFET current (ISW) is sensed and summed with a
slope-compensating ramp. Then it is compared with the
error amplifier output to generate a PWM signal.
Channel 1: VOUT, Channel 2: PG, Hold Time: 11ms
Output Voltage Protection
The MIC24085 turns both high-side and low-side
MOSFETs off to shut down the buck regulator output
voltage when the output voltage exceeds 103% of the
regulated voltage. After the output voltage drops back
below the threshold, the MIC24085 runs to a soft-start.
The loop compensation is designed internally in the
MIC24085 to ensure loop stability, even with a low-ESR
capacitor at the output, such as a ceramic output
capacitor.
PFM Mode at Light Load
Thermal Shutdown
The MIC24085 runs in asynchronous buck mode at light
load, where the bottom MOSFET is turned off when the
inductor current drops to zero. This scheme prevents the
output energy from being pumped back to the input, and
improves the over-all efficiency.
The MIC24085 turns both high-side and low-side
MOSFETs off to shut down the buck regulator output
voltage when the internal temperature is over the setting
threshold at around 170°C. After the temperature drops
back below the threshold, the MIC24085 runs to a soft-
start.
Current Limit and Frequency Foldback
In the MIC24085 ISW is also used to determine over-
current conditions. As the peak inductor current is limited,
the output voltage of the buck converter drops as the load
current increases. When the output voltage reaches 60%
of regulated voltage (or feedback voltage reaches 60% of
0.9V), the switching frequency is forced to fold back, from
1MHz to 250kHz. This current-limit scheme reduces the
average inductor current (even with the same peak
inductor current), and improves the power consumption
at the overload conditions.
The current limit is always active when the regulator is
enabled. Once the overcurrent condition is removed, the
device runs to a soft-start and returns to a normal
operation.
Revision 1.1
October 22, 2013
9
Micrel, Inc.
MIC24085
Transient Response and Control Loop Bandwidth
MIC24085 with adjustable output voltage has been
designed to work under a wide range of input and output
voltages, supporting different values and types of output
capacitance. By design, the MIC24085 has a lower
control loop bandwidth. For designs with aggressive load
step response requirements, using a fixed-output voltage
version with a larger output capacitance is
recommended.
Adjustable Output Voltage: VIN = 12V, VOUT = 5V,
Load Step = 0.5A to 2.5A at 50mA/µs with
1x470µF and 1x100µF output capacitance.
Channel 1: VOUT, Channel 2: PG, Channel 3: Load Step
Revision 1.1
October 22, 2013
10
Micrel, Inc.
MIC24085
Evaluation Board Schematic
Bill of Materials
Item
Part Number
Manufacturer
Murata(5)
Murata
Description
Qty.
C1
GRM31CR61E106KA12
GRM188R71H104KA93D
10µF/25V Ceramic Capacitor, X5R, Size 1206
0.1µF/50V Ceramic Capacitor, X7R, Size 0603
22µF/10V Ceramic Capacitor, X5R, Size 1206
22µF/10V Ceramic Capacitor, X5R, Size 1206
40V Small Signal Schottky Diode, SOD123
1
2
1
1
1
C2, C5
C3
Murata
GRM31CF51A226ZE01L
C4 (Open)
D1 (Open)
Murata
Diodes, Inc.(6)
SK33A
ABC Taiwan Electronics
Corporation(7)
L1
CIP0530LR3R3
3.3µH Inductor, 5A Sat. Current
1
R1, R4
R2, R8
R3
CRCW06033K32FKEA
CRCW060310K0FKEA
CRCW06034K99FKEA
CRCW06031K87FKEA
CRCW06031K24FKEA
CRCW0603732R0FKEA
MIC24085AYML
Vishay Dale(8)
Vishay Dale
Vishay Dale
Vishay Dale
Vishay Dale
Vishay Dale
Micrel Inc.(9)
3.32kΩ Resistor, Size 0603, 1%
10kΩ Resistor, Size 0603, 1%
4.99kΩ Resistor, Size 0603, 1%
1.87kΩ Resistor, Size 0603, 1%
1.24kΩ Resistor, Size 0603, 1%
732Ω Resistor, Size 0603, 1%
18V, 3A, 1MHz Tiny Buck Regulator
1
2
1
1
1
1
1
R5
R6
R7
U1
Notes:
5. Murata: www.murata.com.
6. Diodes, Inc.: www.diodes.com.
7. ABC Taiwan Electronics Corporation: www.atec-group.com.
8. Vishay: www.vishay.com.
9. Micrel, Inc.: www.micrel.com.
Revision 1.1
October 22, 2013
11
Micrel, Inc.
MIC24085
PCB Layout Recommendations
Recommended Component Placement at Top Layer
Revision 1.1
October 22, 2013
12
Micrel, Inc.
MIC24085
PCB Layout Recommendations (Continued)
Top Layer
Mid-Layer 1 (Ground Plane)
Revision 1.1
October 22, 2013
13
Micrel, Inc.
MIC24085
PCB Layout Recommendations (Continued)
Mid-Layer 2 (Ground Plane)
Bottom Layer (Ground Plane)
Revision 1.1
October 22, 2013
14
Micrel, Inc.
MIC24085
Package Information(10) and Recommended Landing Pattern
16-Pin 3mm × 3mm QFN (ML)
Note:
10. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.
Revision 1.1
October 22, 2013
15
Micrel, Inc.
MIC24085
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.
© 2013 Micrel, Incorporated.
Revision 1.1
October 22, 2013
16
相关型号：
MIC24085-CYMLTR
Switching Regulator/Controller, Current-mode, 3A, 1100kHz Switching Freq-Max, PQCC16
MICROCHIP
MIC24085-DYMLTR
Switching Regulator/Controller, Current-mode, 3A, 1100kHz Switching Freq-Max, PQCC16
MICROCHIP
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