MIC22205
2A, Integrated, Switch, High-Efficiency,
Synchronous Buck Regulator with
Frequency Programmable up to 4MHz
General Description
The Micrel MIC22205 is a high-efficiency, 2A, integrated
switch, synchronous buck (step-down) regulator. The
MIC22205 is optimized for highest efficiency, achieving
more than 95% efficiency while still switching at 1MHz.
The ultra-high speed control loop keeps the output voltage
within regulation even under the extreme transient load
swings commonly found in FPGAs and low-voltage ASICs.
The output voltage is pre-bias safe and can be adjusted
down to 0.7V to address all low-voltage power needs.
The MIC22205 offers a full range of sequencing and
tracking options. The Enable/Delay (EN/DLY) pin,
combined with the Power Good (PG) pin, allows multiple
outputs to be sequenced in any way during turn-on and
turn-off. The Ramp Control™ (RC) pin allows the device to
be connected to another product in the MIC22xxx and/or
MIC68xxx family, to keep the output voltages within a
certain
∆V
on start-up.
®
The MIC22205 is available in a 12-pin 3mm x 3mm MLF
with a junction operating range from –40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at:
www.micrel.com.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Input voltage range: 2.9V to 5.5V
Output voltage adjustable down to 0.7V
Output load current up to 2A
Safe start-up into a pre-biased output
Full sequencing and tracking capability
Power Good (PG) output
Efficiency > 95% across a broad load range
Programmable frequency 300kHz to 4MHz
Ultra-fast transient response
Easy RC compensation
100% maximum duty cycle
Fully-integrated MOSFET switches
Thermal-shutdown and current-limit protection
12-pin 3mm x 3mm MLF
®
–40°C to +125°C junction temperature range
Applications
•
•
•
•
•
High power density point-of-load conversion
Servers, routers, and base stations
DVD recorders / Blu-ray players
Computing peripherals
FPGAs, DSP, and low-voltage ASIC power
_________________________________________________________________________________________________________________________
Typical Application
100
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
50
0
0.5
1
1.5
2
V
IN
= 5V
1.8V
Efficiency (V
IN
= 5V)
vs. Output Current
3.3V
MIC22205 2A 1MHz Synchronous Output Converter
OUTPUT CURRENT (A)
Ramp Control 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
August 2011
M9999-082511-A
Micrel, Inc.
MIC22205
Ordering Information
Part Number
MIC22205YML
Note:
1. MLF is a GREEN ROHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
®
Voltage
Adjustable
Junction Temperature Range
–40° to +125°C
Package
(1)
12-Pin 3mm x 3mm MLF
®
Lead Finish
Pb-Free
Pin Configuration
12-Pin 3mm x 3mm MLF
®
(ML)
Pin Description
Pin Number
1
Pin Name
PG
Description
PG (output): This is an open drain output that indicates when the output voltage is below 90% of
its nominal voltage. The PG flag is asserted without delay when the enable is set low or when the
output goes below the 90% threshold.
Ramp Control: A capacitor from the RC pin-to-ground determines slew rate of output voltage
during start-up. The RC pin is internally fed with a 1µA current source. The output voltage tracks
the RC pin voltage. The slew rate is proportional by the internal 1µA source and the RC pin
capacitor. This feature can be used for tracking capability as well as soft start.
Adjustable frequency with external capacitor. Refer to Table 2.
Signal Ground: Internal signal ground for all low power circuits.
Compensation Pin (Input): The MIC22205 uses an internal compensation network containing a
fixed-frequency zero (phase lead response) and pole (phase lag response) which allows the
external compensation network to be much simplified for stability. The addition of a single
capacitor and resistor to the COMP pin will add the necessary pole and zero for voltage mode
loop stability using low-value, low-ESR ceramic capacitors.
Feedback: Input to the error amplifier. The FB pin is regulated to 0.7V. A resistor divider
connecting the feedback to the output is used to adjust the desired output voltage.
Signal Power Supply Voltage (Input): This pin is connected externally to the PVIN pin. A 2.2µF
ceramic capacitor from the SVIN pin to SGND must be placed next to the IC.
Power Supply Voltage (Input): The PVIN pins are the input supply to the internal P-Channel
Power MOSFET. A 10µF ceramic is recommended for bypassing at each PVIN pin. The SVIN
pin must be connected to a PVIN pin.
Switch (Output): This is the connection to the drain of the internal P-Channel MOSFET and drain
of the N-Channel MOSFET. This is a high-frequency, high-power connection; therefore traces
should be kept as short and as wide as practical.
2
3
4
RC
CF
SGND
5
COMP
6
7
8
FB
SVIN
PVIN
9
SW
August 2011
2
M9999-082511-A
Micrel, Inc.
MIC22205
Pin Description (Continued)
Pin Number
10
11
12
EP
Pin Name
PGND
NC
EN/DLY
GND
Description
Power Ground: Internal ground connection to the source of the internal N-Channel MOSFETs.
No Connect: Leave this pin open. Do not connect to ground or route other signal through this.
Enable/Delay (Input): This pin is internally fed with a 1µA current source from SVIN. A delayed
turn on is implemented by adding a capacitor to this pin. The delay is proportional to the
capacitor value. The internal circuits are held off until EN/DLY reaches the enable threshold of
1.24V. This pin is pulled low when the input voltage is lower than the UVLO threshold.
Exposed Pad (Power): Must be connected to the GND plane for full output power to be realized.
August 2011
3
M9999-082511-A
Micrel, Inc.
MIC22205
Absolute Maximum Ratings
(1)
PV
IN
to PGND.................................................... –0.3V to 6V
SV
IN
to PGND..................................................–0.3V to PV
IN
V
SW
to PGND...................................................–0.3V to PV
IN
V
EN/DLY
to PGND .............................................. -0.3V to PV
IN
V
PG
to PGND ...................................................–0.3V to PV
IN
Junction Temperature ................................................ 150°C
PGND to SGND ............................................. –0.3V to 0.3V
Storage Temperature Range ....................–65°C to +150°C
Lead Temperature (soldering, 10s)............................ 260°C
ESD Rating.................................................................Note 2
Operating Ratings
(3)
Supply Voltage (PV
IN
/SV
IN
) ...............................2.9V to 5.5V
Power Good Voltage (V
PG
) .................................. 0V to PV
IN
Enable Input (V
EN/DLY
) .......................................... 0V to PV
IN
Junction Temperature (T
J
) ..................–40°C
≤
T
J
≤
+125°C
Package Thermal Resistance
3mm x 3mm MLF
®
-12 (θ
JC
) ............................ 28.7°C/W
3mm x 3mm MLF
®
-12 (θ
JA
) ............................... 40°C/W
Electrical Characteristics
(4)
SV
IN
= PV
IN
= V
EN/DLY
= 3.3V, V
OUT
= 1.8V, T
A
= 25°C, unless noted. Bold values indicate –40°C< T
J
< +125°C.
Parameter
Power Input Supply
Input Voltage Range (PV
IN
)
Under-Voltage Lockout Trip Level
UVLO Hysteresis
Quiescent Supply Current
Shutdown Current
Reference
Feedback Reference Voltage
Load Regulation
Line Regulation
FB Bias Current
Enable Control
EN/DLY Threshold Voltage
EN Hysteresis
EN/DLY Bias Current
RC Ramp Control
RC Pin Source Current
Oscillator
Switching Frequency
Maximum Duty Cycle
Short Current Protection
Current Limit
Internal FETs
Top MOSFET R
DS(ON)
Bottom MOSFET R
DS(ON)
Notes:
1.
2.
3.
4.
Exceeding the absolute maximum rating may damage the device.
Devices are ESD sensitive. Handling precautions recommended.
The device is not guaranteed to function outside its operating rating.
Specification for packaged product only.
Condition
Min.
2.9
2.55
Typ.
Max.
5.5
2.9
2
10
0.714
Units
V
V
mV
mA
µA
V
%
%
nA
V
mV
µA
µA
MHz
%
A
mΩ
mΩ
PV
IN
rising
V
FB
= 0.9V (not switching)
V
EN/DLY
= 0V
2.719
418
1.3
5
0.7
0.2
0.2
1
1.24
12
1.0
1.0
1.0
0.686
I
OUT
= 100mA to 2A
V
IN
= 2.9V to 5.5V; I
OUT
= 100mA
V
FB
= 0.5V
1.14
V
EN/DLY
= 0.5V; V
IN
= 2.9V and V
IN
= 5.5V
V
RC
= 0.35V
0.6
0.5
0.8
100
2
1.34
1.8
1.7
1.2
V
FB
≤
0.5V
V
FB
= 0.5V
V
FB
= 0.5V, I
SW
= 1A
V
FB
= 0.9V, I
SW
= -1A
5.5
180
100
8
August 2011
4
M9999-082511-A
Micrel, Inc.
MIC22205
Electrical Characteristics
(4)
(Continued)
SV
IN
= PV
IN
= V
EN/DLY
= 3.3V, V
OUT
= 1.8V, T
A
= 25°C, unless noted. Bold values indicate –40°C< T
J
< +125°C.
Parameter
Power Good (PG)
PG Threshold
Hysteresis
PG Output Low Voltage
PG Leakage Current
Over-Temperature Shutdown
Over-Temperature Shutdown
Hysteresis
I
PG
= 5mA (sinking), V
EN/DLY
= 0V
V
PG
= 5.5V; V
FB
= 0.9V
T
J
Rising
151
16
Threshold % of V
FB
from V
REF
−7.5
−10
2.843
139
1.0
2.0
−12.5
%
%
mV
μA
°C
°C
Condition
Min.
Typ.
Max.
Units
August 2011
5
M9999-082511-A
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