MIC2619_11 [MICREL]
1.2MHz PWM Boost Converter with OVP;
| 型号： | MIC2619_11 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 1.2MHz PWM Boost Converter with OVP |
| 文件： | 总15页 (文件大小：685K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2619
1.2MHz PWM Boost Converter
with OVP
General Description
Features
The MIC2619 is a 1.2MHz pulse width modulated (PWM)
step-up switching regulator that is optimized for low power,
high output voltage applications. With a maximum output
voltage of 35V, and a switch current of over 350mA, the
MIC2619 can easily supply most high voltage bias
applications, such as TV tuners.
• 2.8V to 6.5V Input Voltage
• 350mA Switch Current
• Output Voltage up to 35V
• 1.2MHz PWM Operation
• 1.265V Feedback Voltage
• Programmable Over-Voltage Protection (OVP)
• <1% Line Regulation
• <1µA Shutdown Current
• Over-Temperature Protection
• Under-Voltage Lock Out (UVLO)
• Low Profile Thin SOT-23-6 Package
• –40°C to +125°C Junction Temperature Range
The MIC2619 implements a constant frequency 1.2MHz
PWM current-mode control scheme. The high frequency
PWM operation saves board space by reducing external
component sizes. The additional benefit of the constant
frequency PWM control scheme as opposed to variable
frequency control schemes is lower output noise and
smaller input ripple injected back to the battery source.
The MIC2619 has programmable overvoltage protection to
ensure output protection in case of fault condition.
Applications
The MIC2619 is available in a low profile Thin SOT-23 6-
pin package. The MIC2619 has a junction temperature
range of –40°C to +125°C.
• Bias Supply Applications:
-
-
-
-
Tuner Varactor Bias
All support documentation can be found on Micrel’s web
site at: www.micrel.com.
High Voltage Bias Supplies
Avalanche Photo Diode
High Voltage Display Bias
• DSL/Broadband applications
• Constant Current Power Supplies
_________________________________________________________________________________________________________________________
Typical Application
1.2MHz Boost Converter with OVP in Thin SOT-23-6
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-030410-A
March 2010
Micrel, Inc.
MIC2619
Ordering Information
Part Number
Marking(1)
Overvoltage
Protection
Junction Temp.
Range
Package
Lead Finish
MIC2619YD6
2619
Programmable
-40°C to +125°C
Thin SOT-23-6
Lead Free
Note:
1. Under bar( ) symbol may not be to scale.
Pin Configuration
6-Pin TSOT-23 (YD6)
Pin Description
Pin Number
Pin Name Pin Function
1
2
3
SW
GND
FB
Switch Node (Input): Internal power bipolar collector.
Ground.
Feedback (Input): Output voltage sense node. Connect external resistor network to set
output voltage. Nominal feedback voltage is 1.265V.
4
5
6
EN
OVP
VIN
Enable (Input): Logic high enables regulator. Logic low shuts down regulator. Do not
leave floating.
Over-Voltage Protection (Input): Programmable to 35V, adjustable through resistor divider
network.
Supply (Input): 2.8V to 6.5V for internal circuitry. Requires a minimum 1.0µF ceramic
capacitor.
M9999-030410-A
March 2010
2
Micrel, Inc.
MIC2619
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN).........................................................7V
Switch Voltage (VSW)....................................... –0.3V to 40V
Enable Pin Voltage (VEN)..................................... –0.3 to VIN
Feedback Voltage (VFB), (VOVP)........................................6V
Ambient Storage Temperature (TS)...........–65°C to +150°C
ESD Rating (3) .................................................................2kV
Supply Voltage (VIN)......................................... 2.8V to 6.5V
Output Voltage (VOUT) .......................................... VIN to 35V
Junction Temperature Range (TJ).............–40°C to +125°C
Package Thermal Impedance
Thin SOT-23-6 (θJA).........................................177°C/W
Electrical Characteristics (4)
TA = 25°C, VIN = VEN = 3.6V, VOUT = 10V, IOUT = 10mA, unless otherwise noted. Bold values indicate –40°C ≤ TJ ≤125°C.
Min
2.8
1.8
Typ
Max
6.5
2.4
5
Units
V
Parameter
Condition
Supply Voltage Range
Under Voltage Lockout
Quiescent Current
Shutdown Current
Feedback Voltage
Feedback Input Current
Line Regulation
2.1
2.1
V
mA
µA
V
VFB > 1.265V, (not switching)
VEN = 0V
0.04
1.265
-450
0.2
1
1.227
1.303
nA
%
VFB = 1.265V
1
2.8V ≤ VIN ≤ 6.5V
5mA ≤ IOUT ≤ 20mA
0.3
%
Load Regulation
85
90
%
Maximum Duty Cycle
Switch Current Limit
Switch Saturation Voltage
Switch Leakage Current
Enable Threshold
VIN = 3.6V(5)
350
mA
mV
µA
400
VIN = 3.6V, ISW = 300mA
VEN = 0V, VSW = 10V
TURN ON
0.01
1
1.5
V
0.4
TURN OFF
14
1.2
40
µA
MHz
V
Enable Pin Current
Oscillator Frequency
Overvoltage Protection
OVP Input Current
VEN = 6.5V
1.202
1.265
–200
150
10
1.328
nA
°C
VOVP = 1.265V
Hysteresis
Overtemperature Threshold
Shutdown
°C
Notes:
1. Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating
the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(max),
the junction-to-ambient thermal resistance,
, and the ambient temperature, TA. The maximum allowable power dissipation will result in excessive
θJA
die temperature, and the regulator will go into thermal shutdown.
2. This device is not guaranteed to operate beyond its specified operating ratings.
3. Devices are inherently ESD sensitive. Handling precautions required. Human body model: 1.5kΩ in series with 100pF.
4. Specification for packaged product only.
5. Guaranteed by design.
M9999-030410-A
March 2010
3
Micrel, Inc.
MIC2619
Typical Characteristics
Efficiency VOUT = 10V
Efficiency VOUT = 5V
Efficiency VOUT = 12V
100%
90%
80%
70%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
VIN=5V
VIN=4.2V
60%
50%
VIN=5V
VIN=3.6V
VIN=3.3V
VIN=3.3V
VIN=3V
40%
30%
20%
L = 10µH
C = 1µF
L = 10µH
C = 1µF
L = 10µH
C = 1µF
10%
0%
0
20
40
60
80
100
0
50
100
150
200
0
20
40
60
80
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
Load Regulation (VOUT=35V)
Efficiency VOUT = 35V
Load Regulation (VOUT=10V)
35.5
35.4
35.3
35.2
35.1
35.0
34.9
34.8
34.7
34.6
34.5
70%
60%
50%
40%
30%
20%
10%
0%
10.10
10.08
10.06
10.04
10.02
10.00
9.98
VIN=5V
VIN=6.5V
9.96
VIN = 3.6V
VIN = 5V
9.94
L = 10µH
C = 1µF
L = 10µH
C = 1µF
L = 10µH
C = 1µF
9.92
9.90
0
4
8
12
16
0
10 20 30 40 50 60 70
0
2
4
6
8
10
12
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
Frequency
vs. Input Voltage
Line Regulation (VOUT=12V)
Line Regulation (VOUT=35V)
1.50
1.45
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
0.95
0.90
12.20
12.16
12.12
12.08
12.04
12.00
11.96
11.92
11.88
11.84
11.80
35.5
35.4
35.3
35.2
35.1
35.0
34.9
34.8
34.7
34.6
34.5
VOUT = 12V
L = 10µH
C = 1µF
IOUT = 10mA
IOUT = 40mA
L = 10µH
C = 1µF
L = 10µH
C = 1µF
ILOAD = 40mA
3
3.5
4
4.5
5
5.5
6
6.5
3
3.5
4
4.5
5
5.5
6
6.5
4.5
4.9
5.3
5.7
6.1
6.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Quiescent Current
vs. Input Voltage
Switch Current Limit
vs. Input Voltage
Switch Current Limit
vs. Temperature
900
800
700
600
500
400
300
200
100
0
1100
1000
900
800
700
600
500
400
300
200
3.50
3.25
3.00
2.75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
0.50
VIN = 3.6V
VOUT
= 12V
VOUT = 12V
L = 10µH
C = 1µF
VFB = 3V
L = 10µH
C = 1µF
No Switching
-40 -20
0
20 40 60 80 100 120
3
3.5
4
4.5
5
5.5
6
6.5
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
TEMPERATURE (°C)
M9999-030410-A
March 2010
4
Micrel, Inc.
MIC2619
Typical Characteristics (Continued)
Feedback Voltage
vs. Temperature
Switching Frequency
vs. Temperature
1.40
1.34
1.32
1.30
1.28
1.26
1.24
1.22
1.20
1.18
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
0.95
0.90
VIN = 3.6V
VOUT 12V
VIN = 3.6V
VOUT = 12V
IOUT = 25mA
=
IOUT = 25mA
L = 10µH
C = 1µF
L = 10µH
C = 1µF
-40 -20
0
20 40 60 80 100 120
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
Temperature (°C)
M9999-030410-A
March 2010
5
Micrel, Inc.
MIC2619
Functional Characteristics
M9999-030410-A
March 2010
6
Micrel, Inc.
MIC2619
Functional Characteristics (Continued)
M9999-030410-A
March 2010
7
Micrel, Inc.
MIC2619
Functional Diagram
MIC2619 Block Diagram
VIN
Functional Description
VIN provides power to the control and reference circuitry
as well as the switch mode regulator MOSFETs. Due to
The MIC2619 is a constant frequency, PWM current
mode boost regulator. It is composed of an oscillator,
slope compensation ramp generator, current amplifier,
gm error amplifier, PWM generator, and bipolar output
transistor. The oscillator generates a 1.2MHz clock
which triggers the PWM generator to turn on the output
transistor and resets the slope compensation ramp
generator. The current amplifier is used to measure
switch current by amplifying the voltage signal from the
internal sense resistor. The output of the current
amplifier is summed with the output of the slope
compensation ramp generator. This summed current-
loop signal is then fed to one of the inputs of the PWM
generator.
the high speed switching,
a
1µF capacitor is
recommended as close as possible to the VIN and GND
pin.
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 <0.1µA). Also, in the off state,
the output drive is placed in a “tri-stated” condition,
where the bipolar output transistor is in an “off” state or
non-conducting state.
OVP
The gm error amplifier measures the feedback voltage
through the external feedback resistors and amplifies the
error between the detected signal and the 1.265V
reference voltage. The output of the gm error amplifier
provides the voltage-loop signal that is fed to the other
input of the PWM generator. When the current-loop
signal exceeds the voltage loop signal, the PWM
generator turns off the bipolar output transistor. The next
clock period initiates the next switching cycle,
maintaining the constant frequency current-mode PWM
control.
The OVP pin provides over-voltage protection on the
output of the MIC2619. When the OVP circuit is tripped,
the output voltage remains at the set OVP voltage.
Because the OVP circuit operates at a lower frequency
than the feedback circuit, output ripple will be higher
while in an OVP state. OVP requires a resistor divider
network to the output and GND to set the OVP voltage.
If the output voltage overshoots the set OVP voltage,
then the MIC2619 OVP circuit will shut off the switch;
saving itself and other sensitive circuitry downstream.
The accuracy of the OVP pin is ±5% and therefore
should be set above the output voltage to ensure noise
or other variations will not cause a false triggering of the
OVP circuit.
M9999-030410-A
March 2010
8
Micrel, Inc.
FB
MIC2619
voltage associated with this pin, the switch node should
be routed away from sensitive nodes.
The feedback pin provides the control path to control the
output. FB requires a resistor divider network to the
output and GND to set the output voltage.
GND
The ground pin is the ground path for high current PWM
mode. The current loop for the power ground should be
kept as small as possible.
SW
The switching pin connects directly to one end of the
inductor to VIN and the anode of the Schottky diode to
the output. Due to the high switching speed and high
M9999-030410-A
March 2010
9
Micrel, Inc.
MIC2619
The duty cycle required for voltage conversion should be
less than the maximum duty cycle of 85%. Also, in light
load conditions where the input voltage is close to the
output voltage, the minimum duty cycle can cause pulse
skipping. This is due to the energy stored in the inductor
causing the output to slightly overshoot the regulated
output voltage. During the next cycle, the error amplifier
detects the output as being high and skips the following
pulse. This effect can be reduced by increasing the
minimum load or by increasing the inductor value.
Increasing the inductor value also reduces the peak
current.
Application Information
DC-to-DC PWM Boost Conversion
The MIC2619 is a constant-frequency boost converter. It
can convert a low DC input voltage to a higher DC
output voltage. Figure 1 shows a typical circuit. Boost
regulation is achieved by turning on an internal switch,
which draws current through the inductor. When the
switch turns off, the inductor’s magnetic field collapses.
This causes the current to be discharged into the output
capacitor through an external Schottky diode (D1). The
Functional Characteristics show Input Voltage ripple,
Output Voltage ripple, SW Voltage, and Inductor Current
for 10mA load current. Regulation is achieved by
modulating the pulse width i.e., pulse-width modulation
(PWM).
Input Capacitors
A 1µF ceramic capacitor is recommended on the VIN pin
for bypassing. Increasing input capacitance will improve
performance and provide greater noise immunity. The
input capacitor should be as close as possible to the
inductor and the MIC2619, with short traces for good
noise performance.
X5R or X7R dielectrics are recommended for the input
capacitor. Y5V dielectrics lose most of their capacitance
over temperature and are therefore not recommended.
Also, tantalum and electrolytic capacitors alone are not
recommended because of their reduced RMS current
handling, reliability, and ESR increases.
Output Capacitors
Output capacitor selection is also a trade-off between
Figure 1. Typical Application Circuit
Duty Cycle Considerations
performance,
size,
and
cost.
The
minimum
recommended output capacitor is 1µF. Increasing output
capacitance will lead to an improved transient response
but also an increase in size and cost. X5R or X7R
dielectrics are recommended for the output capacitor.
Y5V dielectrics lose most of their capacitance over
temperature and are therefore not recommended.
Duty cycle refers to the switch on-to-off time ratio and
can be calculated as follows for a boost regulator:
VIN
D = 1−
VOUT
Inductor
However at light loads, the inductor will completely
discharge before the end of a switching cycle. The
current in the inductor reaches 0A before the end of the
switching cycle. This is known as discontinuous
conduction mode (DCM). DCM occurs when:
Inductor selection will be determined by the following
(not necessarily in order of importance);
•
•
•
•
Inductance
Rated current value
Size requirements
DC resistance (DCR)
VIN IPEAK
IOUT
<
⋅
VOUT
2
The MIC2619 was designed for use with a 10µH
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 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
Where
⎛
⎜
⎜
⎝
⎞
⎟
⎟
⎠
(
VOUT − VIN
)
⋅
VIN
IPEAK
=
L ⋅ f
VOUT
In DCM, the duty cycle is smaller than in continuous
conduction mode. In DCM the duty cycle is given by:
f ⋅ 2 ⋅L ⋅IOUT
⋅
(
VOUT − VIN
)
D =
VIN
M9999-030410-A
March 2010
10
Micrel, Inc.
MIC2619
saturate the inductor. Peak current can be calculated as
follows:
Diode Selection
The MIC2619 requires an external diode for operation. A
Schottky diode is recommended for most applications
due to their lower forward voltage drop and reverse
recovery time. Ensure the diode selected can deliver the
peak inductor current and the maximum reverse voltage
is rated greater than the output voltage.
⎡
⎤
1− V
⋅ V
IN
⎛
⎜
⎞
⎟
OUT
IPEAK = I
⎢ OUT
+ VOUT
⎥
⎦
2 × f × L
⎝
⎠
⎣
As shown by the previous calculation, the peak inductor
current is inversely proportional to the switching
frequency and the inductance; the lower the switching
frequency or the inductance the higher the peak current.
As input voltage increases the peak current also
increases.
Soft-start
Feed-forward capacitors can be used to provide soft-
start for the MIC2619. Figure 2 shows a typical circuit
for soft-start applications. Typically a 0.22nF feed-
forward capacitor will yield 5ms in rise time.
The size of the inductor depends on the requirements of
the application.
DC resistance (DCR) is also important. While DCR is
inversely proportional to size, DCR can represent a
significant efficiency loss. Refer to the Efficiency
Considerations.
To maintain stability, increasing inductor size will have to
be met with an increase in output capacitance. This is
due to the unavoidable “right half plane zero” effect for
the continuous current boost converter topology. The
frequency at which the right half plane zero occurs can
be calculated as follows:
2
VIN
Frequency =
VOUT ⋅L ⋅IOUT ⋅ 2π
Figure 2. Soft-start Circuit
Feedback resistors
The right half plane zero has the undesirable effect of
increasing gain, while decreasing phase. This requires
that the loop gain is rolled off before this has significant
effect on the total loop response. This can be
accomplished by either reducing inductance (increasing
RHPZ frequency) or increasing the output capacitor
value (decreasing loop gain).
The MIC2619 utilizes a feedback pin to compare the
output to an internal reference. The output voltage is
adjusted by selecting the appropriate feedback resistor
network values. Using the evaluation board schematic
as a reference, the desired output voltage can be
calculated as follows:
⎛
⎜
⎜
⎝
⎞
⎟
⎟
⎠
R4
R5
VOUT = VREF
⋅
+1
Where VREF is equal to 1.265V. Over-voltage Protection
uses the same equation as the feedback pin.
⎛
⎜
⎜
⎝
⎞
⎟
⎟
⎠
R1
R2
VOVP = VREF
⋅
+1
M9999-030410-A
March 2010
11
Micrel, Inc.
MIC2619
MIC2619 Evaluation Board Schematic
Bill of Materials
Item
Part Number
Manufacturer Description
Qty.
C1
C1608X5R1A105K
GRM185R61A105KE36D
0603ZD105KT2A
TAJA106M010R
TDK(1)
Murata(2)
AVX(3)
Capacitor, 1.0µF, 10V, X5R, 0603 size
1
1
1
Capacitor, 1.0µF, 10V, X5R, 0603 size
Capacitor, 1.0µF, 10V, X5R, 0603 size
Capacitor, 10.0µF, 10V, A Case
C2
C3
AVX
C1608X7R11H223K
GRM188R71H223KA01D
06035C223JAT2A
08055D105MAT2A
GRM21BR71H105KA12L
CL21B105KBFNNNE
SK14
TDK
Capacitor, 22nF, 50V, X7R, 0603 size
Capacitor, 22nF, 50V, X7R, 0603 size
Capacitor, 22nF, 50V, X7R, 0603 size
Capacitor, 1.0µF, 50V, X5R, 0805 size
Capacitor, 1.0µF, 50V, X5R, 0805 size
Capacitor, 1.0µF, 50V, X7R, 0805 size
Schottky Diode, 1A, 40V
Murata
AVX
C4
AVX
1
1
1
Murata
Samsung(4)
MCC(5)
Diode, Inc.(6)
Samsung
TDK
D1
L1
B140/B
Schottky Diode, 1A, 40V
C1G22L100MNE
Inductor, 10.0µH, 0.8A, 2.5 x 2.0 x 1.0mm
Inductor, 10.0µH, 0.59A, 2.8 x 3.0 x 1.2mm
Inductor, 10.0µH, 0.7A, 3.2 x 2.5 x 1.55mm
Resistor, 267kΩ, 1%, 1/16W, 0603 size
Resistor, 10kΩ, 1%, 1/16W, 0603 size
Resistor, 100kΩ, 1%, 1/16W, 0603 size
Resistor, 226kΩ, 1%, 1/16W, 0603 size
1.2MHz PWM Boost Converter with OVP
VLF3012ST-100MR59
LQH32PN100MN0L
CRCW0603267KFKEA
CRCW060310K0FKEA
CRCW0603100KFKEA
CRCW0603226KFKEA
MIC2619YD6
Murata
Vishay(7)
Vishay
R1
R2, R5
R3
1
2
1
1
1
Vishay
R4
Vishay
Micrel, Inc.(8)
U1
Notes:
1. TDK: www.tdk.com
2. Murata: www.murata.com
3. AVX: www.avx.com
4. Samsung: www.sem.samsung.com
5. MCC: www.mccsemi.com
6. Diode, Inc.: www.diodes.com
7. Vishay: www.vishay.com
8. Micrel, Inc.: www.micrel.com
M9999-030410-A
March 2010
12
Micrel, Inc.
MIC2619
Recommended Layout
Top Layout
Bottom Layout
M9999-030410-A
March 2010
13
Micrel, Inc.
MIC2619
Package Information
6-Pin TSOT (YD6)
M9999-030410-A
March 2010
14
Micrel, Inc.
MIC2619
Recommended Land Pattern
6-Pin TSOT (YD6)
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.
© 2009 Micrel, Incorporated.
M9999-030410-A
March 2010
15
相关型号：
©2020 ICPDF网 联系我们和版权申明