MIC2251
High-Efficiency Low EMI
Boost Regulator
General Description
Features
The MIC2251 is a general purpose DC/DC boost switching
•
Over 80% efficient for a 300:1 load range
regulator that features low noise, EMI reduction circuitry,
•
2.5V to 5.5V input voltage range
and high efficiency across a wide output current range.
•
Output voltage adjustable to 37V
The MIC2251 is optimized for noise-sensitive hand held
•
52µA (typ) quiescent current
battery powered applications. A proprietary control method
•
Constant peak current control reduces output ripple
allows low ripple across the output voltage and current
ranges. The MIC2251 incorporates a pseudo-random
•
EMI reduction circuitry
dithering function to reduce EMI levels up to 10dB enabled
•
Stable with small ceramic capacitors
by the DITH pin.
•
<1µA shutdown current
The MIC2251 is designed for use with inductor values from
•
UVLO and thermal shutdown
4.7µH to 22µH, and is stable with ceramic capacitors from
1µF to 22µF.
•
8-pin 2mm x 2mm leadless MLF
®
package (MIC2251)
The MIC2251 attains a high peak efficiency up to 90% at
•
5-pin Thin SOT-23 package (MIC2251-1 & -2)
100mA and excellent light load efficiency of 80% at 1mA.
•
–40
°
C to +125
°
C junction temperature range
High power density is achieved with the MIC2251’s
internal 40V/2A rated switch, allowing it to power large
loads in a tiny footprint.
Applications
The MIC2251-1 is available in a 5-pin Thin SOT-23
•
LCD/OLED display bias supply
package with dithering disabled. While the MIC2251-2 is
•
CCD bias supply
available in a 5-pin Thin SOT-23 package with dithering
•
Mobile Phones, PDA, Media Players, GPS PND
enabled. The MIC2251 is available in a 8-pin 2mm x 2mm
®
MLF leadless package option with an operating junction
•
Haptic displays
temperature range of –40°C to +125°C.
•
Local 5V, 15V, 24V rail
Data sheets and support documentation can be found on
Micrel’s web site at:
www.micrel.com.
___________________________________________________________________________________________________________
Typical Application
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
April 2011
M9999-041811-B
Micrel, Inc.
MIC2251
Ordering Information
Part Number
MIC2251YML
MIC2251-1YD5
MIC2251-2YD5
Note:
1.
2.
3.
Pin 1 identifier = “•”.
Over/Underbar (
®
Marking
(1)
Junction Temp. Range
–40° to +125°C
–40° to +125°C
–40° to +125°C
Package
(3)
8-Pin 2mm x 2mm MLF
®
5-Pin Thin SOT-23
5-Pin Thin SOT-23
Lead Finish
Pb-Free
Pb-Free
Pb-Free
ADA
DZ2
(2)
DZ1
(2)
(2)
/__ ) may not be to scale.
MLF is GREEN RoHs compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
Pin Configuration
8-Pin 2mm x 2mm MLF
®
(ML)
(Top View)
5-Pin Thin SOT-23 (D5)
(Top View)
Pin Description
Pin Name
FB
AGND
PGND
SW
NC
VIN
DITH
Pin Number
MIC2251YML
1
2
3
4
5
6
7
Pin Number
MIC2251-1YD5
3
―
2
1
―
5
―
Pin Number
MIC2251-2YD5
3
―
2
1
―
5
4
Pin Function
Feedback (Input): 1.24V output voltage sense node.
V
OUT
= 1.24V (1 + R1/R2)
Analog Ground. Connect to power ground.
Power Ground.
Switch Node (Input): Internal power NMOS drain.
Not Internally Connected.
Supply (Input): 2.5V to 5.5V input voltage.
Frequency Dithering (Input): Connect this pin high to
enable pseudo-random on-time dithering to reduce EMI.
Connect this pin-to-ground to disable this function.
Enable (Input): Logic high enables the regulator. Logic
low shuts down the regulator. Do not leave floating.
Ground (Return): Exposed backside pad. Connect to
power ground.
EN
HS PAD
8
EP
4
―
4
―
April 2011
2
M9999-041811-B
Micrel, Inc.
MIC2251
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) .........................................................6V
Switch Voltage (V
SW
)....................................... –0.3V to 40V
Enable Voltage (V
EN
)......................................... –0.3V to V
IN
FB Voltage (V
FB
)...............................................................6V
Switch Current (I
SW
) ......................................................3.5A
Ambient Storage Temperature (Ts) ..........–65°C to +150°C
ESD Rating
(4)
................................................. ESD Sensitive
Operating Ratings
(2)
Supply Voltage (V
IN
)......................................... 2.5V to 5.5V
Enable Voltage (V
EN
).............................................. 0V to V
IN
Junction Temperature (T
J
)
(3)
..................... –40°C to +125°C
Junction Thermal Resistance
2mm x 2mm MLF
®
-8 (θ
JA
)..................................90°C/W
Electrical Characteristics
(5)
V
IN
= V
EN
= 3.6V; V
DITH
= 0V; V
OUT
= 15V; I
OUT
= 40mA; T
A
= 25°C, unless otherwise noted.
Bold
values indicate
–40°C
≤
T
J
≤
+85°C.
Symbol
V
IN
V
ULVO
I
Q
I
SD
V
FB
I
FB
Tss
t
SW
D
MAX
t
DITH
Parameter
Input Voltage Range
Under-voltage Lockout
Quiescent Current
Shutdown Current
Feedback Voltage
–40°C
≤
T
J
≤
+85°C
Feedback Input Current
Soft Start time
Switch Off-time
Maximum Duty Cycle
Off-time Dithering
Line Regulation
Load Regulation
I
SW
R
ON
I
SW
V
EN
,
V
DITH
I
EN
T
Notes:
1. Absolute maximum ratings indicate limits beyond which damage to the component may occur.
2. The device is not guaranteed to function outside its operating rating.
3. The maximum allowable power dissipation is a function of the maximum junction temperature, T
J(Max)
, the junction-to-ambient thermal resistance,
θ
JA
,
and the ambient temperature, T
A
. The maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into
thermal shutdown.
4. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF.
5. Specification for packaged product only.
6. I
SD
= I
VIN
.
7. Guaranteed by design.
Condition
V
IN
rising
V
FB
= 1.5V (not switching)
V
EN
= 0V,
Note 6
Min
2.5
1.8
Typ
2
70
0.1
Max
5.5
2.4
120
1
1.277
1.29
Units
V
V
µA
µA
V
V
nA
ms
µs
%
%
1.20
1.19
V
FB
= 1.24V
1.24
10
1
PFM Operation
V
IN
= 3.6V
75
V
DITH
= 3.6V. Percentage from nominal.
3V
≤
V
IN
≤
5V
1mA
≤
I
OUT
≤
40mA
Note 7
I
SW
= 200mA
V
EN
= 0V, V
SW
= 10V
Turn ON
Turn OFF
Enable Pin Current
Thermal Shutdown Threshold
Hysteresis
V
EN
= V
IN
= 5.0V
0.1
130
15
1.5
0.4
2
0.9
1.6
87
±20
0.3
0.1
1.6
0.7
0.01
1
5
2
2
%
%
A
Ω
µA
V
V
µA
°C
°C
Switch Current Limit
Switch ON-resistance
Switch Leakage Current
Logic Input Thresholds
April 2011
3
M9999-041811-B
传感器
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