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Micrel Semiconductor
Micrel Semiconductor

MIC2245 Datasheet Preview

MIC2245 Datasheet

PWM Synchronous Buck Regulator

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MIC2245 pdf
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MIC2245
4MHz PWM Synchronous Buck
Regulator with LDO Standby Mode
General Description
The Micrel MIC2245 is a high efficiency 4MHz pulse
width modulated (PWM) synchronous buck (step-
down) regulator that features a LOWQ™ LDO
standby mode that draws only 18µA of quiescent
current. The MIC2245 allows an ultra-low noise,
small size, and high efficiency solution for portable
power applications.
In PWM mode, the MIC2245 operates with a
constant frequency 4MHz PWM control. Under light
load conditions, such as in system sleep or standby
modes, the PWM switching operation can be
disabled to reduce switching losses. In this light
load LOWQ™ mode, the LDO maintains the output
voltage and draws only 18µA of quiescent current.
The LDO mode of operation saves battery life while
not introducing spurious noise and high ripple as
experienced with pulse skipping or bursting mode
regulators.
The MIC2245 operates from a 2.7V to 5.5V input
voltage and features internal power MOSFETs that
can supply up to 500mA output current in PWM
mode. It can operate with a maximum duty cycle of
100% for use in low-dropout conditions.
The MIC2245 is available in the 10-pin 3mm x 3mm
MLF™ package with a junction operating range from
–40°C to +125°C.
Data sheet and support documentation can be found
on Micrel’s web site at: www.micrel.com.
Features
2.7 to 5.5V supply/input voltage
Light load LOWQ™ LDO mode
20µA quiescent current
Low noise, 75µVrms
4MHz PWM mode
Output current to 500mA
>92% efficiency
100% maximum duty cycle
Adjustable output voltage option down to 1V
Fixed output voltage options available
Ultra-fast transient response
Uses a tiny 1µH inductor
Fully integrated MOSFET switches
Micropower shutdown operation
Thermal shutdown and current limit protection
Pb-free 10-pin 3mm x 3mm MLF™ package
–40°C to +125°C junction temperature range
Applications
Cellular phones
PDAs
USB peripherals
____________________________________________________________________________________________________
Typical Application
Adjustable Output Buck Regulator with LOWQ™ Mode
100
90
80
70
60
50
40
30
20
10
00
1.8VOUT Efficiency
VIN=3.2V
VIN=3.6V
VIN=4.2V
100 200 300 400 500
OUTPUT CURRENT (mA)
Patent Pending
LOWQ is a trademark of Micrel, Inc
MLF and MicroLeadFrame are 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
January 2006
M9999-012406
www.micrel.com



Micrel Semiconductor
Micrel Semiconductor

MIC2245 Datasheet Preview

MIC2245 Datasheet

PWM Synchronous Buck Regulator

No Preview Available !

MIC2245 pdf
Micrel, Inc.
MIC2245
Ordering Information
Part Number
Output
Voltage*
Junction
Temperature Range
MIC2245YML
Adj. –40° to +125°C
Note:
* Other Voltage options available. Contact Micrel for details.
Package
10-Pin 3x3 MLF™
Lead Finish
Pb-free
Pin Configuration
AGND 1
LDO 2
BIAS 3
AVIN 4
FB 5
10 PGND
9 SW
8 VIN
7 LOWQ
EP 6 EN
10-Pin 3mm x 3mm MLF (ML)
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
EP
Pin Name
AGND
LDO
BIAS
AVIN
FB
EN
_____
LOWQ
VIN
SW
PGND
GND
Pin Function
Analog (signal) Ground.
LDO Output (Output): Connect to VOUT for LDO mode operation.
Internal circuit bias supply. Must be filtered from input voltage through an RC
lowpass filter with a cutoff frequency
1
2π(20.5)(100nF)
.
Analog Supply/Input Voltage (Input): Supply voltage for the analog control
circuitry and LDO input power. Requires bypass capacitor to GND.
Feedback. Input to the error amplifier. For the Adjustable option, connect to the
external resistor divider network to set the output voltage. For fixed output
voltage options, connect to VOUT and an internal resistor network sets the output
voltage.
Enable (Input). Logic low will shut down the device, reducing the quiescent
current to less than 5µA.
Enable LDO Mode (Input): Logic low enables the internal LDO and disables the
PWM operation. Logic high enables the PWM mode and disables the LDO
mode.
Supply/Input Voltage (Input): Supply voltage for the internal switches and
drivers.
Switch (Output): Internal power MOSFET output switches.
Power Ground.
Ground, backside pad.
January 2006
2 M9999-012406
www.micrel.com


Part Number MIC2245
Description PWM Synchronous Buck Regulator
Maker Micrel Semiconductor
Total Page 14 Pages
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