MIC2807-NNYML-TR [MICROCHIP]
2-CHANNEL POWER SUPPLY SUPPORT CKT, QCC17;
| 型号： | MIC2807-NNYML-TR |
| 厂家： | 
MICROCHIP |
| 描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, QCC17 |
| 文件： | 总18页 (文件大小：433K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2807
RF PA Power Management IC
2MHz, 600mA DC/DC w/DAC Input and
Bypass Switch, Dual Low Noise
200mA/30mA LDO Regulators
General Description
Features
The MIC2807 integrates a high performance 600mA
DC/DC converter intended for powering a power amplifier
(PA) in a mobile phone with dual low noise low dropout
(LDO) regulators for the rest of the RF section. Optimized
for low noise performance, the MIC2807 improves
efficiency in the handset without compromising quality.
• 2.7V to 5.5V input voltage range
• Stable with ceramic output capacitors
• Tiny 17-pin 2.5mm x 2.8mm MLF® Package
• Thermal shutdown protection
• Current limit protection
RF PA Power Supply DC/DC Converter
• Adjustable output power supply – DAC controlled
The MIC2807 has a 2MHz, constant frequency pulse width
modulated (PWM) DC/DC converter designed for low
noise operation and high efficiency. The output voltage
(VOUT) is variable from 0.3V to the input voltage (VIN),
adjustable from 0.3V to 3.6V through a DAC input when
VIN > VOUT. The converter will work in a 100% duty cycle
mode to offer maximum power and efficiency in the
application. In addition to 100% duty cycle, the DC/DC
converter has a bypass mode of operation where the input
voltage node (PVIN pin) is shorted to the output voltage
node (OUT pin) through a 95mΩ switch.
–
VOUT = VDAC x 3
• Bypass mode operation
–
–
Internal 95mꢀ switch between PVIN and OUT pins
VDAC > 1.2V
• Up to 600mA output current in PWM mode
• 100% duty cycle operation for maximum efficiency
• Tiny 4.7µH, 1µF output inductor and capacitor
• Low-noise 2MHz PWM operation
• >90% efficiency
The integrated dual low noise low dropout regulators are
optimized for high PSRR capability and fast turn-on times.
The constant frequency DC/DC converter along with dual
low noise LDO regulators enables a very quiet and
efficient solution for mobile applications.
Dual Low Noise Low Dropout Regulators
• High accuracy – ±2% over temperature
• High PSRR – greater than 70dB
• Very low output noise – 32µVrms
• LDO1 – 200mA output current capability
• LDO2 – 30mA output current capability
The MIC2807 is a µCap design, operating with small
ceramic output capacitors and inductors for stability,
reducing required board space and component cost and it
is available in the tiny 2.5mm x 2.8mm MLF® package.
Applications
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
• CDMA2000 mobile phones
• UMTS/WCDMA mobile phones
• Wibro modules
• WiFi modules
• Power amplifier modules (PAMs) with linear PAs
Typical Application
DC/DC Output Voltage
vs. DAC Voltage
4.5
V
OUT
= 4.2V
= 100mA
IN
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
I
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5
DAC VOLTAGE (V)
CDMA2000/WCDMA RF Power Supply Circuit
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
M9999-022008-B
February 2008
Micrel, Inc.
MIC2807
Ordering Information
Part Number
Marking
Code*
LDO1/LDO2
Voltage**
Junction
Temp. Range
Package
Lead Finish
MIC2807-JJYML
MIC2807-MMYML
MIC2807-NNYML
MIC2807-OOYML
YJJJ
2.5V/2.5V
2.8V/2.8V
2.85V/2.85V
2.9V/2.9V
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
17-Pin 2.5mm x 2.8mm MLF®
17-Pin 2.5mm x 2.8mm MLF®
17-Pin 2.5mm x 2.8mm MLF®
17-Pin 2.5mm x 2.8mm MLF®
Pb-Free
Pb-Free
Pb-Free
Pb-Free
YJMM
YJNN
YJOO
Notes:
MLF® is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
* Over bar ( ) symbol may not be to scale.
** Other voltage options available. Please contact Micrel for details.
Pin Configuration
17-Pin 2.5mm x 2.8mm MLF® (ML)
(Top View)
M9999-022008-B
February 2008
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Micrel, Inc.
MIC2807
Pin Description
Pin Number
Pin Name Pin Function
1
DAC
DAC Control Input (Analog Voltage Input). Provides control of output voltage of DC/DC converter.
The output voltage is 3x’s the DAC voltage (Ex. 0.5VDAC = 1.5VOUT) when VIN > VOUT. Bypass mode is
enabled when the DAC voltage exceeds 1.2V or VIN ≤ VOUT. VOUT = VDAC x 3.
2
3
BYP
AGND
EN2
Filter capacitor for LDO1 and LDO2 internal voltage reference, connect capacitor to ground.
Signal ground of chip.
4
Enables the LDO2 regulator.
5
VIN
LDO1 and LDO2 Supply Voltage. Must be connected to PIN 15.
Output of the LDO1.
6
LDO1
LDO2
OUT
PGND
SW
7
Output of the LDO2.
8, 9
10
11
12
13
14
15
Drain of internal bypass switch, also serves as feedback for the internal regulator.
Power ground.
Switch: Internal power MOSFET output switches of DC/DC converter.
Supply Voltage: Requires bypass capacitor to ground.
Enables LDO1 Regulator.
PVIN
EN1
EN
Enables the DC/DC Converter.
AVIN
Supply voltage for DC/DC converter control circuitry and reference voltage circuit. Must be connected
to PIN 5.
16, 17
NC
No Connect.
M9999-022008-B
February 2008
3
Micrel, Inc.
MIC2807
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (PVIN, AVIN, VIN) ............................ 0V to 6V
Output Switch Voltage (VSW)............................................6V
DAC Input Voltage (VDAC).......................................0V to VIN
Logic Input Voltage (VEN, VEN1, VEN2) .....................0V to VIN
Power Dissipation(3)...................................Internally Limited
Storage Temperature (Ts) .........................–65°C to +150°C
ESD Rating(4)................................................................±2kV
Supply Voltage (PVIN, AVIN, VIN) ...................... 2.7V to 5.5V
Output Voltage (VOUT) ............................................ 0V to VIN
Enable Voltage (VEN, VEN1, VEN2)............................ 0V to VIN
DAC Input Voltage (VDAC).................................... 0.1V to VIN
Junction Temperature (TJ) ........................–40°C to +125°C
Thermal Resistance
2.5x2.8mm MLF-17 (θJA)...................................70°C/W
Electrical Characteristics(5)
DC/DC Converter
VIN = PVIN = AVIN = VEN = 3.6V; VDAC = 0.6V; VEN1 = VEN2 = 0V; L = 4.7µH; COUT = 1µF; TA = 25°C, bold values indicate
–40°C< TJ < +125°C, unless noted.
LDO1/LDO2
VIN = VEN1 = VEN2 = 3.6V; COUTLDO1 = 2.2µF; VEN = 0V; COUTLDO2 = 1µF; IOUT = 100µA; TA = 25°C, bold values indicate
–40°C< TJ < +125°C, unless noted.
Parameter
Condition
Min
2.7
Typ
Max
5.5
Units
MIC2807
Supply Voltage Range
Total Quiescent Current
V
VEN = VEN1 = VEN2 = 3.6V
VDAC = 0.6V (DC/DC: not switching)
480
µA
Enable Pin Threshold
Logic Low
Logic High
0.4
V
V
1.3
Enable Pin Hysteresis
30
0.01
2.6
mV
µA
V
Enable Pin Input Current
1
Under-Voltage
(turn-on)
2.7
Lockout Threshold
UVLO Hysteresis
85
160
20
mV
ºC
Shutdown Temperature
Shutdown Temperature
Hysteresis
ºC
Total Shutdown Current
VEN = VEN1 = VEN2 = 0V
1
5
µA
DC/DC Converter [VEN1 = VEN2 = 0V]
Maximum Duty Cycle
100
%
Bypass Quiescent
Current
VDAC = 1.3V
490
650
µA
Quiescent Current
Output Voltage
VDAC = 0.6V (regulator on, not switching)
VDAC = 0.6V, ILOAD = 0mA
360
1.8
450
1.854
0.5
µA
V
1.746
Output Voltage
Line Regulation
3.0V< VIN < 4.5, ILOAD = 10mA
0.05
%/V
Output Voltage
Load Regulation
0mA < IOUT < 400mA
0.2
1
%
Switch On-Resistance
ISW = -100mA, High-Side Switch
0.55
0.6
0.75
0.85
1.6
ꢀ
ꢀ
A
I
SW = 100mA, Low-Side Switch
Current Limit
0.65
0.85
(Peak SW Current)
Frequency
1.8
2
2.2
MHz
M9999-022008-B
February 2008
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Micrel, Inc.
MIC2807
Parameter
Condition
Min
Typ
25
Max
50
2
Units
µs
Turn-On Time
DAC Input Current
IOUT = 100µA
0.15
3
µA
Output Voltage/
DAC Voltage
(internally set)
V/V
Bypass Switch
Threshold
DAC Voltage required to enable bypass mode
1.176
1.2
35
1.224
V
Bypass Switch
Hysteresis
mV
Bypass Transition Time
Delay from VDAC = 1.3V to VOUT = 0.90VIN
VIN = 3.0V, IBYPASS = 100mA
10
95
40
µs
Bypass Switch
On-Resistance
150
mꢀ
Bypass Switch Leakage
5
µA
A
Bypass Over-Current
Limit
1
1.4
2.5
Current Limit Retry Time
32
µs
%
Current Limit Retry
Duty Cycle
12.5
LDO1/LDO2 [VEN = 0V]
Total Ground Current(8)
Turn-on Time
VEN1 = VEN2 = 3.6V
220
30
µA
µs
LDO1 or LDO2; CBYP = 0.1µF
100
LDO1 [VEN = 0V]
Output Voltage Accuracy Variation from nominal VOUT
–40°C to +125°C
–1
+1
+2
%
%
–2
Line Regulation
VIN = VOUT +1V to 5.5V
IOUT = 100µA to 200mA
IOUT = 50mA; VOUT > 2.8V
0.02
0.2
20
0.3
0.5
%/V
%
Load Regulation(6)
Dropout Voltage(7)
mV
mV
mV
µA
I
I
OUT = 150mA; VOUT > 2.8V
OUT = 200mA; VOUT > 2.8V
55
70
120
300
Ground Pin Current(8)
Ripple Rejection
IOUT = 0mA; EN2 = GND
f = up to 1kHz; CBYP = 0.1µF
f = 1kHz – 20kHz; CBYP = 0.1µF
VOUT = 0V
190
70
dB
45
dB
Current Limit
225
300
32
700
mA
µVRMS
Output Voltage Noise
LDO2 [VEN = 0V]
CBYP=0.1µF, 10Hz to 100kHz
Output Voltage Accuracy Variation from nominal VOUT
–40°C to +125°C
–1
+1
+2
%
%
–2
Line Regulation
VIN = VOUT +1V to 5.5V
IOUT = 100µA to 30mA
IOUT = 10mA; VOUT > 2.8V
0.02
0.2
10
0.3
0.5
%/V
%
Load Regulation(6)
Dropout Voltage(7)
mV
mV
µA
I
OUT = 30mA; VOUT > 2.8V
30
70
Ground Pin Current(8)
Ripple Rejection
IOUT = 0mA; EN1 = GND
f = up to 1kHz; CBYP = 0.1µF
f = 1kHz – 20kHz; CBYP = 0.1µF
VOUT = 0V
190
65
300
dB
40
dB
Current Limit
40
60
150
mA
µVRMS
Output Voltage Noise
CBYP = 0.1µF, 10Hz to 100kHz
32
M9999-022008-B
February 2008
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Micrel, Inc.
MIC2807
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. The maximum allowable power dissipation of any TA (ambient temperature) is PD(max) = (TJ(max) - TA) / θJA. Exceeding 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.
5. Specification for packaged product only.
6. Regulation is measured at constant junction temperature using low duty cycle pulse testing, changes in output voltage due to heating effects are
covered by the thermal regulation specification.
7. Dropout voltage is defined as the input-to-output differential at which the output voltage drops 2% below its nominal value measured at 1V differential.
8. Ground pin current is the regulator quiescent current.
M9999-022008-B
February 2008
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Micrel, Inc.
MIC2807
Typical Characteristics (DC/DC)
1V
DC/DC Efficiency
1.2V
DC/DC Efficiency
OUT
1.5V
DC/DC Efficiency
OUT
OUT
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
V
V
V
= 4.2V
= 3.6V
= 3V
IN
IN
IN
V
V
V
= 4.2V
= 3.6V
= 3V
IN
IN
IN
V
= 4.2V
= 3.6V
= 3V
IN
V
IN
V
IN
0
0.1
0.2
0.3
0.4
0.5
0
0.1
0.2
0.3
0.4
0.5
0
0.1
0.2
0.3
0.4
0.5
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
1.8V
DC/DC Efficiency
2.5V
DC/DC Efficiency
OUT
DC/DC Line Regulation
OUT
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
1.220
1.215
1.210
1.205
1.200
V
V
V
= 4.2V
= 3.6V
= 3V
IN
IN
IN
V
V
V
= 4.2V
= 3.6V
= 3V
IN
IN
IN
V
OUT
V
= 1.2V
OUT
I
= 100mA
= 0.4V
DAC
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
0
0.1
0.2
0.3
0.4
0.5
0
0.1
0.2
0.3
0.4
0.5
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
DC/DC Switching Frequency
vs. Input Voltage
DC/DC Current Limit
vs. Input Voltage
DC/DC Output Voltage
vs. DAC Voltage
2.8
1.5
1.3
1.1
0.9
0.7
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
V
OUT
= 4.2V
IN
I
= 100mA
2.6
2.4
2.2
2.0
1.8
1.6
1.4
V
V
OUT
= 0.5V
= 1.5V
DAC
OUT
I
= 300mA
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5
DAC VOLTAGE (V)
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
DC/DC Load Regulation
DC/DC Switching Frequency
vs. Temperature
1.825
3.5
3.0
2.5
2.0
1.5
1.0
0.5
1.823
1.821
1.819
1.817
1.815
V
V
V
= 3.6V
IN
= 0.5V
= 1.5V
DAC
OUT
V
IN
= 3.6V
I
= 300mA
OUT
0
0.1
0.2
0.3
0.4
0.5
-40 -20
0
20 40 60 80 100 120
OUTPUT CURRENT (A)
TEMPERATURE (°C)
M9999-022008-B
February 2008
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Micrel, Inc.
MIC2807
Typical Characteristics (LDO1/LDO2)
LDO2 Load Regulation
LDO2 Line Regulation
LDO2 Dropout Voltage
vs. Output Current
2.808
2.806
2.804
2.802
2.800
2.810
2.805
2.800
2.795
2.790
35
30
25
20
15
10
5
I
= 15mA
OUT
OUT
V
= 3.6V
OUT
IN
C
V
= 2.8V
OUT
C
= 1µF
= 1µF
0
3
6
9
12 15 18 21 24 27 30
OUTPUT CURRENT (mA)
0
5
10 15 20 25 30
OUTPUT CURRENT (mA)
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
Power Supply Rejection
LDO1 Dropout Voltage
vs. Temperature
Power Supply Rejection
Ratio LDO2 [I
=20mA]
Ratio LDO2 [I
=1mA]
OUT
OUT
90
80
70
60
50
40
30
20
10
0
65
100
90
80
70
60
50
40
30
20
10
0
60
55
50
45
V
V
I
= 3.6V
V
V
I
= 3.6V
IN
OUT
IN
OUT
= 2.8V
= 2.8V
V
V
I
= 3.6V
IN
OUT
= 1mA
= 1µF
= 20mA
= 1µF
OUT
= 2.8V
= 150mA
OUT
C
C
OUT
OUT
OUT
0.01 0.1
1
10
100 1000
0.01 0.1
1
10
100 1000
-40 -20
0
20 40 60 80 100 120
FREQUENCY (kHz)
FREQUENCY (kHz)
TEMPERATURE (°C)
LDO1 Ground Current
vs. Output Current
LDO1 Ground Current
vs. Temperature
LDO1 Line Regulation
250
240
230
220
210
200
310
290
270
250
230
210
190
170
150
2.81
2.80
2.79
2.78
2.77
2.76
V
V
I
= 3.6V
IN
OUT
I
= 100mA
= 2.2µF
= 2.8V
= 150mA
OUT
V
V
= 3.6V
IN
OUT
C
OUT
= 2.8V
OUT
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
0
30
60
90
120 150
-40 -20
0
20 40 60 80 100 120
OUTPUT CURRENT (mA)
TEMPERATURE (°C)
Power Supply Rejection
Power Supply Rejection
Ratio LDO1 [I =100mA]
LDO1 Dropout Voltage
vs. Output Current
Ratio LDO1 [I
=5mA]
OUT
OUT
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
80
70
60
50
40
30
20
10
0
V
V
I
= 3.6V
IN
OUT
V
V
= 3.6V
= 2.8V
IN
OUT
= 2.8V
= 5mA
OUT
V
= 2.8V
C
= 2.2µF
OUT
C
= 2.2µF
OUT
OUT
0.1
1
10
100
1000
5
45
85
125 165 205
0.01 0.1
1
10
100 1000
FREQUENCY (kHz)
OUTPUT CURRENT (mA)
FREQUENCY (kHz)
M9999-022008-B
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Micrel, Inc.
MIC2807
Typical Characteristics (LDO1/LDO2 cont.)
LDO1/LDO2 Output Noise
Spectral Density
10
1
0.1
0.01
V
V
= 4.2V
IN
OUT
C
= 2.8V
= 1µF
OUT
0.001
0.01 0.1
1
10 100 1000 10000
FREQUENCY (kHz)
M9999-022008-B
February 2008
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Micrel, Inc.
MIC2807
Functional Characteristics
DC/DC PWM Waveforms
DC/DC Start-Up Waveforms
V
V
= 3.6V
IN
OUT
= 300mA
= 1.8V
I
OUT
L = 4.7µH
= 1µF
V
V
= 3.6V
I
= 100mA
C
= 1µF
IN
OUT
= 1.8V L = 4.7µH
OUT
OUT
C
OUT
Time (400ns/div)
Time (10µs/div)
DC/DC Load Transient
300mA
V
V
= 3.6V
IN
= 1.8V
OUT
L = 4.7µH
= 1µF
C
10mA
OUT
Time (20µs/div)
M9999-022008-B
February 2008
10
Micrel, Inc.
MIC2807
Functional Characteristics (cont.)
LDO1 Start-Up Waveforms
LDO1 Load Transient
200mA
V
V
= 3.6V
IN
OUT
= 200mA
10mA
= 2.8V
V
V
= 3.6V
I
IN
OUT
C
= 2.2µF
= 2.8V
OUT
OUT
OUT
C
= 2.2µF
Time (10µs/div)
Time (20µs/div)
M9999-022008-B
February 2008
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Micrel, Inc.
MIC2807
Functional Diagram
MIC2807 Block Diagram
M9999-022008-B
February 2008
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Micrel, Inc.
MIC2807
VIN
Device Functional Description
VIN provides power to the LDO1 and the LDO2 control
sections of the MIC2807. A minimum 1µF capacitor,
2.2µF recommended, should be placed as close as
possible between the VIN and AGND pins. VIN must
have the same voltage as AVIN*.
The MIC2807 is a power management IC with a single
integrated step-down regulator and two low dropout
regulators. LDO1 is a 200mA low dropout regulator and
LDO2 is a 30mA low dropout regulator. The 500mA
pulse-width-modulated (PWM) step-down regulator
utilizes a dynamically adjustable output voltage for
powering RF power amplifiers. By dynamically adjusting
the output power as necessary, battery life can be
dramatically improved in battery powered RF power
OUT
The OUT pin connects the internal bypass drain and the
feedback signal to the output. The bypass applies the
input voltage through a low resistance (95mꢀ typical) P-
Channel MOSFET switch. The feedback signal provides
the control path to set the output at 3 times the DAC
voltage.
amplifier applications.
Also where high power is
required, the step-down PWM regulator has a bypass
mode where an internal 95mꢀ switch shorts the OUT
and PVIN pins together.
SW
Pin Functional Description
The SW pin connects directly to the inductor and
provides the switching current necessary to operate in
PWM mode. Due to the high speed switching on this pin,
the switch node should be routed away from sensitive
nodes.
PVIN
PVIN (Power VIN) provides power to the MOSFETs for
the step-down switching regulator section of the
MIC2807, along with the current limit sensing circuitry.
Due to the high switching speeds, a minimum 1µF
capacitor is recommended close to PVIN and the power
ground (PGND) pin for bypassing*.
PGND
PGND (Power GND) is the ground path for the
MOSFETs in the step-down regulator section. The
current loop for the power ground should be as small as
possible and separate from the analog ground (AGND)
loop*.
AVIN
AVIN (Analog VIN) provides power to the internal
reference and control section of the step-down regulator.
AVIN, VIN, and PVIN must all be tied together. Careful
layout should be considered to ensure high frequency
switching noise caused by PVIN is reduced before
reaching AVIN*.
AGND
AGND (Analog GND) 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*.
DAC
The DAC pin is the control pin that sets the output
voltage of the step-down regulator. The Output voltage is
3X the voltage set on the DAC pin (VOUT = VDAC x 3).
When 1.2V or greater is applied to the DAC pin, the
MIC2807’s step-down regulator enters bypass mode. In
bypass mode, the input supply is connected to the
output through a 95mꢀ P-Channel MOSFET.
LDO1
Regulated output voltage of the LDO1. Power is
provided by VIN. Recommended output capacitance is
2.2µF.
LDO2
Regulated output voltage of the LDO2. Power is
provided by VIN. Recommended output capacitance is
1µF.
EN/EN1/EN2
The EN pin provides a logic level control of the step-
down regulator output. In the off state, supply current of
the device is greatly reduced (typically ≤1µA). Also, in
the off state, the output drive and bypass switch are
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. EN1 provides logic
control for LDO1, and EN2 provides logic control for
LDO2. Placing a logic high voltage on any one of the
respective enable pins (EN, EN1 or EN2) will turn-on
(powering up the bias and control circuitry) that
respective regulator (DC/DC, LDO1 or LDO2). Do not
drive the enable pins above the supply voltage (AVIN
and VIN).
BYP
Filter capacitor for the voltage reference for the LDO1
and the LDO2. A 100nF capacitor is recommended from
the BYP pin to ground.
* Refer to PCB layout section of this data sheet for optimal layout
principles.
M9999-022008-B
February 2008
13
Micrel, Inc.
MIC2807
Inductor Selection
Component Selection
The MIC2807 is designed for use with a 4.7µH inductor.
Proper selection should ensure that 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, so that the peak current will
not saturate the inductor. Peak inductor current can be
calculated as follows:
Output Capacitor
LDO1 output requires a 2.2µF ceramic capacitor, while
the LDO2 and DC/DC regulator outputs require a 1µF
ceramic capacitor. All output capacitor values can be
increased to improve transient response, but perform-
ance has been optimized for a 2.2µF ceramic capacitor
for LDO1 and 1µF ceramic capacitors for both the
DC/DC regulator and LDO2. X7R/X5R dielectric-type
ceramic capacitors are recommended because of their
temperature performance. X5R/X7R-type capacitors
change capacitance by 15% over their operating
temperature range and are the most stable type of
ceramic capacitors. Z5U and Y5V dielectric capacitors
change value by as much as 50% to 60% respectively
over their operating temperature ranges.
⎛
⎞
VOUT
⎜
⎟
⎟
VOUT 1−
⎜
V
IN
⎝
⎠
IPK = IOUT
+
2× f ×L
Input Capacitor
IPK:
IOUT
VIN:
Peak Inductor Current
Output/Load Current
Input Voltage
For optimal bypassing a minimum 1µF ceramic, 2.2µF
recommended, should be placed as close as possible to
the VIN pin. X5R or X7R dielectrics are recommended
for the input capacitor. Y5V dielectrics lose most of their
capacitance over temperature and are therefore, not
recommended. For high frequency filtering a minimum
1µF is recommended close to the VIN and PGND pins.
Smaller case size capacitors are recommended due to
their lower ESR and ESL. Please refer to the PCB layout
section for an example of an appropriate circuit layout.
:
VOUT
f:
:
Output Voltage
Switching Frequency of PWM Regulator
Inductor Value
L:
M9999-022008-B
February 2008
14
Micrel, Inc.
MIC2807
PCB Layout
Layout Schematic
M9999-022008-B
February 2008
15
Micrel, Inc.
MIC2807
Top Layer
M9999-022008-B
February 2008
16
Micrel, Inc.
MIC2807
Bottom Layer
M9999-022008-B
February 2008
17
Micrel, Inc.
MIC2807
Package Information
17-Pin 2.5mm x 2.8mm 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.
© 2006 Micrel, Incorporated.
M9999-022008-B
February 2008
18
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