MIC24085
18V, 3A, 1MHz, High-Performance,
Integrated FET Buck Regulator
in Tiny 3mm × 3mm QFN
General Description
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.
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.
Datasheets and support documentation are available on
Micrel’s web site at:
www.micrel.com.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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
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
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
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
October 22, 2013
Revision 1.1
Micrel, Inc.
MIC24085
Ordering Information
Part Number
MIC24085AYML
MIC24085BYML
MIC24085CYML
MIC24085DYML
MIC24085EYML
MIC24085FYML
Output Voltage
ADJ
1.5V
1.8V
2.5V
3.3V
5V
–40°C to +125°C
16-Pin 3mm x 3mm QFN
Pb-Free
Junction Temperature Range
Package
Lead Finish
Pin Configuration
16-Pin 3mm × 3mm QFN
(ML)
(Top View)
Pin Description
Pin Number
1, 12, 13, 16
2, 3, 11
4
5
6, 7
8
9
10
14,15
EP
Pin Name
SW
VCC
GND
FB
NC
PG
EN
BST
PGND
ePAD
Pin Function
Switch Node (Output): Power stage output. Connect an inductor to this pin.
Supply Voltage (for control circuit and power stage): A ceramic input capacitor between VCC and
the power ground (PGND) is required.
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.
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.
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.
Power Ground: PGND is the ground path for the power stage.
Exposed Pad. It must be connected to PGND on the PCB.
October 22, 2013
2
Revision 1.1
Micrel, Inc.
MIC24085
Absolute Maximum
Ratings
(1)
V
VCC
to PGND................................................
−0.3V
to +20V
V
SW
to PGND .................................................
−0.3V
to +20V
V
EN
, V
FB
, V
PG,
to GND .....................................
−0.3V
to + 6V
V
BST
to V
SW
.....................................................
−0.3V
to + 6V
V
BST
to PGND ................................................
−0.3V
to +26V
PGND to GND .............................................
−0.3V
to + 0.3V
Junction Temperature .............................................. +150°C
Storage Temperature (T
S
) .........................
−65°C
to +150°C
Lead Temperature (soldering, 10sec) ........................ 260°C
(3)
ESD Rating .................................................................. 2kV
Operating Ratings
(2)
Supply Voltage (V
VCC
) ....................................... 4.5V to 18V
Output Current ................................................................ 3A
Junction Temperature (T
J
) ........................
−40°C
to +125°C
Junction Thermal Resistance
MLF-16 (θ
JA
) ..................................................... 68°C/W
MLF-16 (θ
JC
) .................................................... 7.5°C/W
Electrical Characteristics
(4)
V
VCC
= 12V; T
A
= 25°C, unless noted.
Bold
values indicate
−40°C
≤ T
J
≤ +125°C.
Parameter
Power Supply Input
V
CC
Input Voltage Range
Quiescent Supply Current
Shutdown Supply Current
V
CC
UVLO Threshold
V
CC
UVLO Hysteresis
Reference (MIC24085AYML)
Feedback Reference Voltage
FB Bias Current
Soft-Start Time
Load Regulation
Line Regulation
Enable Control
EN Logic Level High
EN Logic Level Low
EN Hysteresis
EN Bias Current
PWM
Switching Frequency
Foldback Switching Frequency
Maximum Duty Cycle
Minimum Duty Cycle
Notes:
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.
Condition
Min.
4.5
Typ.
Max.
18
Units
V
mA
µA
V
mV
No Switching, V
FB
= 1.5V
V
EN
= 0V
2.3
5
4.3
650
10
4.5
-40°C ≤ T
J
≤ +125°C (±1.5%)
V
FB
= 0.6V
I
OUT
= 100mA to 3A
V
VCC
= 4.5V to 18V
0.886
0.9
50
4
0.5
0.5
0.914
500
V
nA
ms
%
%
V
2.2
0.8
480
V
EN
= 5V
V
EN
= 0V
V
FB
= 0.9V
V
FB
< 60% × 0.9V
V
FB
= 0V, 1MHz
V
FB
= 1V
0.9
3.5
-1.5
1.0
250
97
0
1.1
V
mV
µA
MHz
kHz
%
%
October 22, 2013
3
Revision 1.1
Micrel, Inc.
MIC24085
Electrical Characteristics
(4)
(Continued)
V
VCC
= 12V; T
A
= 25°C, unless noted.
Bold
values indicate
−40°C
≤ T
J
≤ +125°C.
Parameter
Internal MOSFET
High Side On-Resistance
Low Side On-Resistance
Overcurrent Protection
Current-Limit Threshold
Power Good
Power Good Threshold Voltage
Power Good Hysteresis
Power Good Low Voltage
Power Good Recovery Hold Time
Thermal Protection
Overtemperature Shutdown
Overtemperature Shutdown Hysteresis
T
J
Rising
170
10
°C
°C
Sweep V
FB
from Low-to-High
Sweep V
FB
from High-to-Low
V
FB
< 90% x V
NOM
, I
PG
= -0.3mA
PG recovery after power
restoration
9
91
93
1.5
50
11
100
12
95
%V
OUT
%V
OUT
mV
ms
V
FB
= 0.9V
3.4
3.8
4.4
A
I
SW
= 1A
I
SW
= 1A
135
90
mΩ
mΩ
Condition
Min.
Typ.
Max.
Units
October 22, 2013
4
Revision 1.1
Micrel, Inc.
MIC24085
Typical Characteristics
T
J
=
−40°C
to +125°C, V
CC
= 12V (unless otherwise noted).
October 22, 2013
5
Revision 1.1
DIY/Open Source Hardware
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