MIC2205-1.5YMLTR [MICREL]

2A SWITCHING REGULATOR, 2200kHz SWITCHING FREQ-MAX, PDSO10, 3 X 3 MM, LEAD FREE, MLF-10;
MIC2205-1.5YMLTR
型号: MIC2205-1.5YMLTR
厂家: MICREL SEMICONDUCTOR    MICREL SEMICONDUCTOR
描述:

2A SWITCHING REGULATOR, 2200kHz SWITCHING FREQ-MAX, PDSO10, 3 X 3 MM, LEAD FREE, MLF-10

稳压器 开关
文件: 总16页 (文件大小:454K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
MIC2205  
2MHz PWM Synchronous Buck  
Regulator with LDO Standby Mode  
General Description  
Features  
The Micrel MIC2205 is a high efficiency 2MHz PWM  
synchronous buck (step-down) regulator that  
features a LOWQ™ LDO standby mode that draws  
only 18µA of quiescent current. The MIC2205  
allows an ultra-low noise, small size, and high  
efficiency solution for portable power applications.  
2.7 to 5.5V supply voltage  
Light load LOWQ™ LDO mode  
18µA quiescent current  
Low noise, 75µVrms  
2MHz PWM mode  
Output current to 600mA  
>95% efficiency  
100% maximum duty cycle  
In PWM mode, the MIC2205 operates with a  
constant frequency 2MHz 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.  
Adjustable output voltage option down to 1V  
Fixed output voltage options available  
Ultra-fast transient response  
Stable with 1µF ceramic output capacitor  
Fully integrated MOSFET switches  
Micropower shutdown  
Thermal shutdown and current limit protection  
Pb-free 3mm x 3mm MLF-10L package  
–40°C to +125°C junction temperature range  
The MIC2205 operates from 2.7V to 5.5V input and  
features internal power MOSFETs that can supply  
up to 600mA output current in PWM mode. It can  
operate with a maximum duty cycle of 100% for use  
in low-dropout conditions.  
Applications  
The MIC2205 is available in the 3mm x 3mm MLF-  
10L package with a junction operating range from  
–40°C to +125°C.  
Cellular phones  
PDAs  
USB peripherals  
Data sheets and support documentation can be  
found on Micrel’s web site at www.micrel.com.  
____________________________________________________________________________________________________  
Typical Application  
MIC2205  
2.2µH  
1.8VOUT Efficiency  
VIN  
8
4
9
2
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
VOUT  
VIN  
SW  
2.7V to 5.5V  
VIN = 3V  
AVIN  
LDO  
6
7
3
R1  
100k  
C3  
100pF  
C1  
1µF  
EN  
VIN = 3.6V  
VIN = 4.2V  
5
FB  
LOWQ  
BIAS  
LowQ  
C4  
2.2µF  
R2  
125k  
C2  
0.1µF  
PGND AGND  
10  
1
GND  
GND  
0
100 200 300 400 500 600  
OUTPUT CURRENT (mA)  
Adjustable Output Buck Regulator with LOWQ™ Mode  
Patent Pending  
LOWQ is a trademark of Micrel, 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  
M9999-041105  
www.micrel.com  
April 2005  
Micrel, Inc.  
MIC2205  
Ordering Information  
Part Number  
MIC2205-1.3YML  
MIC2205-1.38YML  
MIC2205-1.5YML  
MIC2205-1.58YML  
MIC2205-1.8YML  
MIC2205-1.85YML  
MIC2205YML  
Output Voltage(1)  
Junction Temp. Range  
–40° to +125°C  
–40° to +125°C  
–40° to +125°C  
–40° to +125°C  
–40° to +125°C  
–40° to +125°C  
–40° to +125°C  
Package  
Lead Finish  
Pb-free  
Pb-free  
Pb-free  
Pb-free  
Pb-free  
Pb-free  
Pb-free  
1.3V  
1.38V  
1.5V  
1.58V  
1.8V  
1.85V  
Adj.  
3x3 MLF-10L  
3x3 MLF-10L  
3x3 MLF-10L  
3x3 MLF-10L  
3x3 MLF-10L  
3x3 MLF-10L  
3x3 MLF-10L  
Note:  
1. Other Voltage options available. Contact Micrel for details.  
Pin Configuration  
AGND  
1
10 PGND  
LDO 2  
BIAS 3  
9
8
7
6
SW  
VIN  
AVIN  
4
LOWQ  
EN  
FB 5  
EP  
3mm x 3mm MLF-10L (ML)  
Pin Description  
Pin Number  
Pin Name  
AGND  
LDO  
Pin Function  
Analog (signal) Ground.  
LDO Output (Output): Connect to VOUT for LDO mode operation.  
1
2
3
BIAS  
Internal circuit bias supply. Must be de-coupled to signal ground with a 0.1µF  
capacitor and should not be loaded.  
4
5
AVIN  
FB  
Analog Supply 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.  
6
7
EN  
Enable (Input). Logic low will shut down the device, reducing the quiescent  
current to less than 5µA.  
_____  
LOWQ  
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.  
8
9
VIN  
SW  
Supply Voltage (Input): Supply voltage for the internal switches and drivers.  
Switch (Output): Internal power MOSFET output switches.  
Power Ground.  
10  
EP  
PGND  
GND  
Ground, backside pad.  
M9999-041105  
www.micrel.com  
April 2005  
2
Micrel, Inc.  
MIC2205  
Absolute Maximum Ratings(1)  
Operating Ratings(2)  
Supply Voltage (VIN) ............................................ +6V  
Output Switch Voltage (VSW) ............................... +6V  
Output Switch Current (ISW)................................... 2A  
Logic Input Voltage (VEN,VLOWQ) .............. -0.3V to VIN  
Storage Temperature (Ts)................ -60°C to +150°C  
ESD Rating(3) ....................................................... 3kV  
Supply Voltage (VIN)............................+2.7V to +5.5V  
Logic Input Voltage (VEN,VLOWQ) .............. -0.3V to VIN  
Junction Temperature (TJ).............. –40°C to +125°C  
Junction Thermal Resistance  
3x3 MLF-10L (θJA) ................................... 60°C/W  
Electrical Characteristics (4)  
VIN = VEN = VLOWQ =3.6V; L = 2.2µH; COUT = 2.2µF; TA = 25°C, unless noted. Bold values indicate –40°C< TJ < +125°C  
Parameter  
Condition  
Min  
2.7  
Typ  
Max  
5.5  
Units  
Supply Voltage Range  
V
V
Under-Voltage Lockout  
Threshold  
(turn-on)  
2.45  
2.55  
2.65  
UVLO Hysteresis  
100  
690  
mV  
µA  
Quiescent Current, PWM  
mode  
VFB = 0.9 * VNOM (not switching)  
VLOWQ = 0V;IOUT = 0mA  
VEN = 0V  
900  
29  
5
Quiescent Current, LDO  
mode  
16  
µA  
Shutdown Current  
0.01  
1
µA  
V
0.99  
0.98  
1.01  
1.02  
[Adjustable] Feedback  
Voltage  
± 1%  
± 2% (over temperature)  
-1  
-2  
+1  
+2  
[Fixed Output] Voltages  
FB pin input current  
Nominal VOUT tolerance  
%
1
1
nA  
A
Current Limit in PWM Mode VFB = 0.9 * VNOM  
0.75  
1.85  
Output Voltage Line  
Regulation  
VOUT > 2V; VIN = VOUT+300mV to 5.5V; ILOAD= 100mA  
VOUT < 2V; VIN = 2.7V to 5.5V; ILOAD= 100mA  
0.13  
%
Output Voltage Load  
Regulation, PWM Mode  
20mA < ILOAD < 300mA  
0.2  
0.1  
0.5  
0.2  
%
%
Output Voltage Load  
Regulation, LDO Mode  
100µA < ILOAD < 50mA  
VLOWQ = 0V  
Maximum Duty Cycle  
100  
%
VFB 0.4V  
ISW = 50mA VFB = 0.7VFB_NOM (High Side Switch)  
ISW = -50mA VFB = 1.1VFB_NOM (Low Side Switch)  
0.4  
0.4  
2
PWM Switch ON-  
Resistance  
Oscillator Frequency  
1.8  
0.5  
2.2  
1.3  
MHz  
V
LOWQ threshold voltage  
0.85  
LOWQ Input Current  
Enable Threshold  
0.1  
0.85  
0.1  
2
1.3  
2
µA  
V
0.5  
Enable Input Current  
LDO Dropout Voltage  
µA  
mV  
I
OUT = 50mA Note 5  
110  
M9999-041105  
www.micrel.com  
April 2005  
3
Micrel, Inc.  
MIC2205  
Parameter  
Condition  
Min  
60  
Typ  
Max  
Units  
Output Voltage Noise  
LDO Current Limit  
75  
LOWQ = 0V; COUT = 2.2μF, 10Hz to 100kHz  
LOWQ = 0V; VOUT = 0V (LDO Mode)  
µVrms  
120  
160  
mA  
Over-Temperature  
Shutdown  
°C  
Over-Temperature  
Hysteresis  
20  
°C  
Notes  
1. Exceeding the absolute maximum rating may damage the device.  
2. The device is not guaranteed to function outside its operating rating.  
3. Devices are ESD sensitive. Handling precautions recommended. Human body model: 1.5kin series with 100pF.  
4. Specification for packaged product only.  
5. Dropout voltage is defined as the input-to-output differential at which the output voltage drops 2% below its nominal value that is  
initially measured at a 1V differential. For outputs below 2.7V, the dropout voltage is the input-to-output voltage differential with a  
minimum input voltage of 2.7V.  
M9999-041105  
www.micrel.com  
April 2005  
4
Micrel, Inc.  
MIC2205  
Typical Characteristics – PWM Mode  
Bode Plot  
2.5VOUT Efficiency  
1.8VOUT Efficiency  
80  
70  
60  
50  
40  
30  
20  
10  
0
144  
126  
108  
90  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
VIN = 3V  
VIN = 3V  
Phase  
VIN = 3.6V  
VIN = 4.2V  
VIN = 3.6V  
72  
VIN = 4.2V  
54  
VIN = 3.6V  
VOUT = 1.8V  
L = 2.2  
OUT = 2.2  
CFF = 120pF  
36  
18  
H
0
Gain  
C
F
-10  
-20  
100  
-18  
-36  
1M  
1E+2 1E+3 1E+4 1E+5 1E+6  
1k  
10k  
100k  
0
0
0
100  
200  
300  
400  
400  
400  
5.5  
0
100 200 300 400 500 600  
OUTPUT CURRENT (mA)  
FREQUENCY (Hz)  
OUTPUT CURRENT (mA)  
1.5VOUT Efficiency  
1.38VOUT Efficiency  
1.2VOUT Efficiency  
95  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
VIN = 3V  
VIN = 3V  
VIN = 3V  
90  
85  
80  
75  
70  
65  
60  
55  
50  
VIN = 3.6V  
VIN = 4.2V  
VIN = 3.6V  
VIN = 4.2V  
VIN = 3.6V  
VIN = 4.2V  
0
100  
200  
300  
400  
100  
200  
300  
0
100  
200  
300  
400  
OUTPUT CURRENT (mA)  
OUTPUT CURRENT (mA)  
OUTPUT CURRENT (mA)  
Quiescent Current  
vs. Supply Voltage  
1.0VOUT Efficiency  
Load Regulation  
90  
85  
80  
75  
70  
65  
60  
55  
50  
1.010  
1.008  
1.006  
1.004  
1.002  
1.000  
0.998  
0.996  
0.994  
0.992  
0.990  
900  
800  
700  
600  
500  
400  
300  
200  
100  
0
VIN = 3V  
VIN = 3.6V  
VIN = 4.2V  
VIN = 3.6V  
FB = 0.9V  
VIN = 3.6V  
LowQ = VIN  
V
2.7  
3.4  
4.1  
4.8  
5.5  
0
100 200 300 400 500 600  
OUTPUT CURRENT (mA)  
100  
200  
300  
SUPPLY VOLTAGE (V)  
OUTPUT CURRENT (mA)  
Frequency  
vs. Temperature  
Peak Current Limit  
vs. Supply Voltage  
Enable Threshold  
vs. Supply Voltage  
2.2  
2.15  
2.1  
1200  
1000  
800  
600  
400  
200  
0
1.5  
1.4  
1.3  
1.2  
1.1  
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
2.05  
2
1.95  
1.9  
1.85  
1.8  
VIN = 3.6V  
LowQ = VIN  
LowQ = VIN  
2.7 3.4  
SUPPLY VOLTAGE (V)  
-40 -20  
0
20 40 60 80 100 120  
TEMPERATURE (°C)  
2.7  
3.4  
4.1  
4.8  
4.1  
4.8  
5.5  
SUPPLY VOLTAGE (V)  
M9999-041105  
www.micrel.com  
April 2005  
5
Micrel, Inc.  
MIC2205  
Typical Characteristics – PWM Mode (cont.)  
Turn-On Time  
vs. Supply Voltage  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
VIN = 3.6V  
0
2.7  
3.4  
4.1  
4.8  
5.5  
SUPPLY VOLTAGE (V)  
M9999-041105  
www.micrel.com  
April 2005  
6
Micrel, Inc.  
MIC2205  
Typical Characteristics - LDO Mode  
PSRR  
vs. Input Voltage  
PSRR  
vs. Output Current  
Dropout  
vs. Output Current  
80  
60  
40  
20  
0
80  
60  
40  
20  
0
250  
200  
150  
100  
50  
IOUT = 0A  
IOUT = 100 A  
4.2V  
3.6V  
3V  
IOUT = 50mA  
VOUT = 1.8V  
COUT = 2.2 F  
VIN = 3.6  
VOUT = 1.8V  
COUT = 2.2 F  
VOUT = 3.3V  
IOUT = 50mA  
0
1E-2 1E-1 1E+0 1E+1 1E+2 1E+3  
1E-2 1E-1 1E+0 1E+1 1E+2 1E+3  
0
20  
40  
60  
80  
100  
1
1
10  
FREQUENCY (Hz)  
1k  
10  
FREQUENCY (Hz)  
1k  
0.01 0.1  
100  
0.01 0.1  
100  
OUTPUT CURRENT (mA)  
Current Limit  
vs. Supply Voltage  
Dropout Voltage  
vs. Temperature  
Dropout Voltage  
vs. Temperature  
140  
120  
100  
80  
160  
140  
120  
100  
80  
80  
70  
60  
50  
40  
30  
20  
10  
0
60  
60  
40  
40  
VOUT = 3.3V  
OUT = 50mA  
LowQ = 0V  
20 40 60 80 100 120  
TEMPERATURE (°C)  
VOUT = 3.3V  
IOUT = 25mA  
LowQ = 0V  
I
20  
20  
LowQ = 0V  
0
0
2.7  
3.4  
4.1  
4.8  
5.5  
-40 -20  
0
-40 -20  
0
20 40 60 80 100 120  
SUPPLY VOLTAGE (V)  
TEMPERATURE (°C)  
Dropout Voltage  
vs. Temperature  
Dropout Voltage  
vs. Temperature  
Output Voltage  
vs. Temperature  
40  
35  
30  
25  
20  
15  
10  
5
9
8
7
6
5
4
3
2
1
0
1.836  
1.827  
1.818  
1.809  
1.800  
1.791  
1.782  
1.773  
1.764  
VOUT = 3.3V  
OUT = 10mA  
LowQ = 0V  
20 40 60 80 100 120  
TEMPERATURE (°C)  
VOUT = 3.3V  
OUT = 1mA  
I
I
LowQ = 0V  
20 40 60 80 100 120  
TEMPERATURE (°C)  
LowQ = 0V  
0
-40 -20  
0
-40 -20  
0
20 40 60 80 100 120  
-40 -20 0  
TEMPERATURE (°C)  
Enable Threshold Voltage  
vs. Supply Voltage  
Turn-On Time  
Quiescent Current  
vs. Temperature  
vs. Supply Voltage  
1.5  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
25  
20  
15  
10  
5
IOUT = 50mA  
IOUT = 1mA  
IOUT = 100 A  
1.4  
1.3  
1.2  
1.1  
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
VIN = 3.6V  
LowQ = 0V  
VIN = 3.6V  
LowQ = 0V  
LowQ = 0V  
4.8  
0
2.7  
3.4  
4.1  
5.5  
2.7  
3.4  
4.1  
4.8  
5.5  
-40 -20  
0
20 40 60 80 100 120  
SUPPLY VOLTAGE (V)  
SUPPLY VOLTAGE (V)  
TEMPERATURE (°C)  
M9999-041105  
www.micrel.com  
April 2005  
7
Micrel, Inc.  
MIC2205  
Typical Characteristics – LDO Mode (cont.)  
Quiescent Current  
vs. Temperature  
Quiescent Current  
Quiescent Current  
vs. Supply Voltage  
vs. Output Current  
25  
20  
15  
10  
5
25  
24  
23  
22  
21  
20  
19  
18  
17  
16  
15  
25  
24  
23  
22  
21  
20  
19  
18  
17  
16  
15  
IOUT = 60mA  
IOUT = 100 A  
IOUT = 0A  
IOUT = 100 A  
LowQ = 0V  
VIN = 3.6V  
LowQ = 0V  
LowQ = 0V  
0
0
1
2
3
4
5
2.7  
3.4  
4.1  
4.8  
5.5  
0
20  
40  
60  
80  
100  
SUPPLY VOLTAGE (V)  
SUPPLY VOLTAGE (V)  
OUTPUT CURRENT (mA)  
Output Voltage  
vs. Output Current  
1.836  
1.827  
1.818  
1.809  
1.8  
1.791  
1.782  
1.773  
1.764  
VIN = 3.6V  
V
OUT =1.8V  
LowQ = 0V  
60 80  
OUTPUT CURRENT (mA)  
0
20  
40  
100  
M9999-041105  
www.micrel.com  
April 2005  
8
Micrel, Inc.  
MIC2205  
Functional Diagram  
VIN  
AVIN  
P-Channel  
Current Limit  
6
BIAS  
HSD  
SW  
VOUT  
PWM  
Control  
Anti-Shoot  
Through  
COUT  
LSD  
N-Channel  
Current Limit  
R1  
R2  
EN  
Bias,  
UVLO,  
Thermal  
Shutdown  
FB  
Enable and  
Control Logic  
Soft  
EA  
Start  
LOWQ  
1.0V  
LDO Block  
LDO  
Current  
Limit  
EA  
1.0V  
LDO  
SGND  
PGND  
MIC2205 Block Diagram  
M9999-041105  
www.micrel.com  
April 2005  
9
Micrel, Inc.  
MIC2205  
Functional Characteristics  
Load Transient PWM Mode  
LowQ = VIN  
Time 20 s/div  
Enable Transient PWM Mode  
LowQ = 0V  
Time 40 s/div  
M9999-041105  
www.micrel.com  
April 2005  
10  
Micrel, Inc.  
MIC2205  
Functional Characteristics  
M9999-041105  
www.micrel.com  
April 2005  
11  
Micrel, Inc.  
MIC2205  
Functional Description  
for bypassing.  
VIN  
VIN provides power to the MOSFETs for the switch  
mode regulator section, along with the current  
limiting sensing. Due to the high switching speeds, a  
1µF capacitor is recommended close to VIN and the  
power ground (PGND) pin for bypassing. Please  
refer to layout recommendations.  
FB  
The feedback pin (FB) provides the control path to  
control the output. For adjustable versions, a resistor  
divider connecting the feedback to the output is used  
to adjust the desired output voltage. The output  
voltage is calculated as follows:  
R1  
R2  
AVIN  
VOUT = VREF  
×
+1  
Analog VIN (AVIN) provides power to the LDO  
section and the bias through an internal 6 Ohm  
resistor. AVIN and VIN must be tied together.  
Careful layout should be considered to ensure high  
frequency switching noise caused by VIN is reduced  
before reaching AVIN.  
where VREF is equal to 1.0V.  
A feedforward capacitor is recommended for most  
designs using the adjustable output voltage option.  
To reduce battery current draw, a 100K feedback  
resistor is recommended from the output to the FB  
pin (R1). Also, a feedforward capacitor should be  
connected between the output and feedback (across  
R1). The large resistor value and the parasitic  
capacitance of the FB pin can cause a high  
frequency pole that can reduce the overall system  
phase margin. By placing a feedforward capacitor,  
these effects can be significantly reduced.  
Feedforward capacitance (CFF) can be calculated as  
follows:  
LDO  
The LDO pin is the output of the linear regulator and  
should be connected to the output. In LOWQ mode  
(LOWQ<1.5V), the LDO provides the output voltage.  
In PWM mode (LOWQ>1.5V) the LDO pin is high  
impedance.  
EN  
The enable pin provides a logic level control of the  
output. In the off state, supply current of the device  
is greatly reduced (typically <1µA). Also, in the off  
state, the output drive is placed in a "tri-stated"  
condition, where both the high side P-channel  
Mosfet and the low-side N-channel are in an “off” or  
non-conducting state. Do not drive the enable pin  
above the supply voltage.  
1
CFF  
=
2π ×R1×160kHz  
For fixed options A feed forward capacitor from the  
output to the FB pin is required. Typically a 100pF  
small ceramic capacitor is recommended  
SW  
The switch (SW) pin connects directly to the inductor  
and provides the switching current nessasary to  
operate in PWM mode. Due to the high speed  
switching on this pin, the switch node should be  
routed away from sensitive nodes.  
LOWQ  
The LOWQ pin provides a logic level control  
between the internal PWM mode and the low noise  
linear regulator mode. With LOWQ pulled low  
(<0.5V), quiescent current of the device is greatly  
reduced by switching to a low noise linear regulator  
mode that has a typical IQ of 18µA. In linear (LDO)  
mode the output can deliver 60mA of current to the  
output. By placing LOWQ high (>1.5V), this  
transitions the device into a constant frequency  
PWM buck regulator mode. This allows the device  
the ability to efficiently deliver up to 600mA of output  
current at the same output voltage.  
PGND  
Power ground (PGND) is the ground path for the  
high current PWM mode. The current loop for the  
power ground should be as small as possible and  
separate from the Analog ground (AGND) loop.  
Refer to the layout considerations for more details.  
SGND  
Signal ground (SGND) is the ground path for the  
biasing and control circuitry. The current loop for the  
signal ground should be separate from the Power  
ground (PGND) loop. Refer to the layout  
considerations for more details.  
BIAS  
The BIAS pin supplies the power to the internal  
power to the control and reference circuitry. The bias  
is powered from AVIN through an internal 6Ω  
resistor. A small 0.1µF capacitor is recommended  
M9999-041105  
www.micrel.com  
April 2005  
12  
Micrel, Inc.  
MIC2205  
Applications Information  
Output Capacitor  
The MIC2205 is a 600mA PWM power supply that  
utilizes a LOWQ™ light load mode to maximize  
battery efficiency in light load conditions. This is  
achieved with a LOWQ control pin that when pulled  
low, shuts down all the biasing and drive current for  
the PWM regulator, drawing only 18µA of operating  
current. This allows the output to be regulated  
through the LDO output, capable of providing 60mA  
of output current. This method has the advantage of  
producing a clean, low current, ultra low noise output  
in LOWQ™ mode. During LOWQ™ mode, the SW  
node becomes high impedance, blocking current  
flow. Other methods of reducing quiescent current,  
such as pulse frequency modulation (PFM) or  
bursting techniques, create large amplitude, low  
frequency ripple voltages that can be detrimental to  
system operation.  
Even though the MIC2205 is optimized for a 2.2µF  
output capacitor, output capacitance can be varied  
from 1µF to 4.7µF. The MIC2205 utilizes type III  
internal compensation and utilizes an internal high  
frequency zero to compensate for the double pole  
roll off of the LC filter. For this reason, larger output  
capacitors can create instabilities. X5R or X7R  
dielectrics are recommended for the output  
capacitor. Y5V dielectrics lose most of their  
capacitance over temperature and are therefore, not  
recommended.  
In addition to a 2.2µF, a small 10nF is recommended  
close to the load for high frequency filtering. Smaller  
case size capacitors are recommended due to there  
lower ESR and ESL.  
Inductor Selection  
When more than 60mA is required, the LOWQ pin  
can be forced high, causing the MIC2205 to enter  
PWM mode. In this case, the LDO output makes a  
"hand-off" to the PWM regulator with virtually no  
variation in output voltage. The LDO output then  
turns off allowing up to 600mA of current to be  
efficiently supplied through the PWM output to the  
load.  
The MIC2205 is designed for use with a 2.2µH  
inductor. Proper selection should ensure the  
inductor can handle the maximum average and peak  
currents required by the load. Maximum current  
ratings of the inductor are generally given in two  
methods; permissible DC current and saturation  
current. Permissible DC current can be rated either  
for a 40°C temperature rise or a 10% to 20% loss in  
inductance. Ensure that the inductor selected can  
handle the maximum operating current. When  
saturation current is specified, make sure that there  
is enough margin that the peak current will not  
saturate the inductor. Peak inductor current can be  
calculated as follows:  
Input Capacitor  
A minimum 1µF ceramic is recommended on the  
VIN pin for bypassing. X5R or X7R dielectrics are  
recommended for the input capacitor. Y5V  
dielectrics lose most of their capacitance over  
temperature and are therefore, not recommended.  
VOUT  
VOUT 1−  
A minimum 1µF is recommended close to the VIN  
and PGND pins for high frequency filtering. Smaller  
case size capacitors are recommended due to their  
lower ESR and ESL. Please refer to layout  
recommendations for proper layout of the input  
capacitor.  
V
IN  
IPK = IOUT  
+
2× f ×L  
M9999-041105  
www.micrel.com  
April 2005  
13  
Micrel, Inc.  
MIC2205  
Layout Recommendations  
VOUT  
GND  
VIN  
LowQ  
EN  
CFF  
R1  
R2  
Top  
VOUT  
GND  
VIN  
LowQ  
EN  
CFF  
R1  
R2  
Bottom  
Note:  
The above figures demonstrate the recommended layout for the MIC2205 adjustable option.  
M9999-041105  
www.micrel.com  
April 2005  
14  
Micrel, Inc.  
MIC2205  
MIC2205  
VIN  
2.2µH  
VIN  
8
4
9
2
VOUT  
SW  
2.7V to 5.5V  
AVIN  
LDO  
6
7
3
R1  
C3  
100pF  
C1  
1µF  
EN  
100k  
5
FB  
LOWQ  
BIAS  
LowQ  
C4  
2.2µF  
R2  
125k  
C2  
0.1µF  
PGND AGND  
10  
1
GND  
GND  
Adjustable Output  
MIC2205  
2.2µH  
VIN  
8
4
9
2
VOUT  
VIN  
SW  
2.7V to 5.5V  
AVIN  
LDO  
6
7
3
C3  
100pF  
C1  
1µF  
EN  
5
FB  
LOWQ  
BIAS  
LowQ  
C4  
2.2µF  
C2  
0.1µF  
PGND AGND  
10  
1
GND  
GND  
Fixed Output  
Item  
Part Number  
Description  
Manufacturer  
Qty  
C1  
1µF Ceramic Capacitor X5R, 6.3V 0603  
1µF Ceramic Capacitor X5R, 6.3V 0603  
06036D105MAT2  
GRM185R60J105KE21D  
AVX  
1
Murata(4)  
C4  
2.2µF Ceramic Capacitor X5R, 10V 0603  
2.2µuF Ceramic Capacitor X5R, 10V 0603  
06036D225MAT2  
GRM188R61A225KE34  
AVX  
1
1
1
Murata(4)  
C3  
C2  
VJ0402A101KXAA  
100pF Ceramic Capacitor  
Vishay(3)  
0201ZD103MAT2  
GRM033R10J103KA01D  
10nF Ceramic Capacitor 6.3V 0201  
10nF Ceramic Capacitor 6.3V 0201  
AVX  
Murata(4)  
L1  
2.2µH Inductor 97m3.2mmx2.5mmx1.55mm  
2.2µH Inductor 94m3.2mmx3.2mmx1.55mm  
LQH32CN2R2M53K  
CDRH2D14-2R2  
Murata(4)  
1
1
Sumida(2)  
R1(1)  
CRCW04021002F  
100k1% 0402  
Vishay Dale(3)  
R2(1) CRCW04026652F  
CRCW04021243F  
Vishay Dale(3)  
Vishay Dale(3)  
Vishay Dale(3)  
Vishay Dale(3)  
Vishay Dale(3)  
66.5 k1% 0402 For 2.5VOUT  
124 k1% 0402 For 1.8 VOUT  
200 k1% 0402 For 1.5 VOUT  
402 k1% 0402 For 1.2 VOUT  
CRCW04022003F  
CRCW04024023F  
Open  
For 1.0 VOUT  
U1  
MIC2205BML  
2MHz Synchronous Buck Regulator with LOWQTM  
Mode  
Micrel, Inc.(5)  
1
Notes:  
1. For adjustable version only.  
2. Sumida Tel: 408-982-9660  
3. Murata Tel: 949-916-4000  
4. Vishay Tel: 402-644-4218  
5. Micrel, Inc. Tel: 408-944-0800  
M9999-041105  
www.micrel.com  
April 2005  
15  
Micrel, Inc.  
MIC2205  
Package Information  
10-Lead MLF™ (ML)  
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  
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel  
for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.  
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.  
© 2004 Micrel, Incorporated.  
M9999-041105  
www.micrel.com  
April 2005  
16  

相关型号:

MIC2205-1.85YML

2MHz PWM Synchronous Buck Regulator with LDO Standby Mode
MICREL

MIC2205-1.85YML

2A SWITCHING REGULATOR, 2200kHz SWITCHING FREQ-MAX, DSO10
MICROCHIP

MIC2205-1.85YMLTR

2A SWITCHING REGULATOR, 2200kHz SWITCHING FREQ-MAX, PDSO10, 3 X 3 MM, LEAD FREE, MLF-10
MICREL

MIC2205-1.8YML

2MHz PWM Synchronous Buck Regulator with LDO Standby Mode
MICREL

MIC2205YML

2MHz PWM Synchronous Buck Regulator with LDO Standby Mode
MICREL

MIC2205YML-TR

2A SWITCHING REGULATOR, 2200kHz SWITCHING FREQ-MAX, PDSO10
MICROCHIP

MIC2205YMLTR

2 A SWITCHING REGULATOR, 2200 kHz SWITCHING FREQ-MAX, PDSO10, 3 X 3 MM, LEAD FREE, MLF-10
ROCHESTER

MIC2205_06

2MHz PWM Synchronous Buck Regulator with LDO Standby Mode
MICREL

MIC2206

2MHz PWM Synchronous Buck Regulator with LOWQ Mode and Voltage Scaling
MICREL

MIC2206-1.2YMLTR

2A SWITCHING REGULATOR, 2200kHz SWITCHING FREQ-MAX, PDSO10, 3 X 3 MM, LEAD FREE, MLF-10
MICREL

MIC2206-1.8YML

2A SWITCHING REGULATOR, 2200kHz SWITCHING FREQ-MAX, PDSO10
MICROCHIP

MIC2206-9IYML-TR

IC REG PWM SYNC BUCK 2MHZ 10-MLF
MICROCHIP