MIC2601/2

MIC2601/2
1.2A, 1.2 / 2MHz Wide Input Range
Integrated Switch Boost Regulator
General Description
Features
The MIC2601/2 is a 1.2 and 2MHz, PWM DC/DC boost
switching regulator available in a 2mm x 2mm MLF®
package. High power density is achieved with the
MIC2601/2’s internal 40V/1.2A switch, allowing it to power
large loads in a tiny footprint.
The MIC2601/2 implements constant frequency 1.2/2MHz
PWM current mode control. The MIC2601/2 offers internal
compensation that provides excellent transient response
and output regulation performance. The high frequency
operation saves board space by allowing small, low-profile
external components. The fixed frequency PWM scheme
also reduces spurious switching noise and ripple to the
input power source.
Soft start reduces in rush current and is programmable via
external capacitor.
The MIC2601/2 is available in a 2mm x 2mm 8-pin MLF®
leadless package. Both devices have an output overvoltage protection feature.
The MIC2601/2 has an operating junction temperature
range of –40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
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•
•
•
•
•
•
•
•
•
•
•
Wide input voltage range: 4.5V to 20V
Output voltage adjustable to 40V
1.2A switch current
MIC2601 operates at 1.2MHz
MIC2602 operates at 2MHz
Stable with small size ceramic capacitors
High efficiency
Programmable soft start
<10µA shutdown current
UVLO
Output over-voltage protection
Over temperature shutdown
8-pin 2mm x 2mm MLF® package
–40°C to +125°C junction temperature range
Applications
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•
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Multimedia STB/Antenna
Broadband communications
TFT-LCD bias supplies
Bias supply
Positive output regulators
SEPIC converters
DSL applications
Local boost regulators
___________________________________________________________________________________________________________
Typical Application
10µH
18VOUT Efficiency
VOUT
18V, 500mA
MIC2601/2
VIN = 12V
2.2µF
0.1µF
VIN
SW
EN
FB
VDD
SS
AGND PGND
100K
70
60
50
10µF
0.1µF
100
90
80
4K
8VIN
12VIN
40
30
20
10
0
0 100 200 300 400 500 600 700 800
LOAD CURRENT (mA)
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
June 2008
M9999-062508-A
Micrel, Inc.
MIC2601/2
Ordering Information
Part Number
Marking
Frequency
Output Over
Voltage Protection
Temperature Range
Package
MIC2601YML
SXA
1.2MHz
40V
–40° to +125°C
8-Pin 2mm x 2mm MLF®
Pb-Free
–40° to +125°C
®
Pb-Free
MIC2602YML
SXA
2MHz
40V
Lead Finish
8-Pin 2mm x 2mm MLF
Pin Configuration
VIN
1
8
PGND
VDD
2
7
SW
EN
3
6
FB
AGND
4
5
SS
8-Pin 2mm x 2mm MLF® (ML)
Pin Description
Pin Number
Pin Name
1
VIN
Supply (Input): 4.5V to 20V input voltage.
2
VDD
Internal regulator
June 2008
3
EN
4
AGND
5
SS
Pin Function
Enable (Input): Logic high enables regulator. Logic low shuts down regulator.
Analog Ground
Soft Start
6
FB
Feedback (Input): 1.24V output voltage sense node. VOUT = 1.24V ( 1 + R1/R2)
7
SW
Switch Node (Input): Internal power BIPOLAR collector.
8
PGND
Power ground
2
M9999-062508-A
Micrel, Inc.
MIC2601/2
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) .......................................................22V
Switch Voltage (VSW)....................................... –0.3V to 40V
Enable Voltage (VEN)......................................... –0.3V to VIN
FB Voltage (VFB)...............................................................6V
Ambient Storage Temperature (Ts) ...........–65°C to +150°C
ESD Rating..................................................................... 2kV
Supply Voltage (VIN).......................................... 4.5V to 20V
Enable Voltage (VEN)............................................ 0V to 20V
Junction Temperature (TJ) ........................ –40°C to +125°C
Junction Thermal Resistance
2mm x 2mm MLF-8 (θJC) ...................................90°C/W
Electrical Characteristics(3)
TA = 25°C, VIN = VEN = 12V; unless otherwise noted. Bold values indicate –40°C ≤ TJ ≤ +125°C.
Symbol
Parameter
VIN
Input Voltage Range
Condition
Min
4.5
VDD
Under-voltage Lockout
For VDD
IQ
Quiescent Current
VFB = 2V (not switching)
1.8
ISD
Shutdown Current
VEN = 0V, Note 4
VFB
Feedback Voltage
(±2%)
1.225
(±3%) (over temperature)
1.212
Units
20
V
V
2.1
2.4
V
4.3
6
mA
0.1
2
µA
1.25
1.275
V
1.288
V
Feedback Input Current
VFB = 1.24V
–550
Line Regulation
8V ≤ VIN ≤ 14V
0.04
Load Regulation
5mA ≤ IOUT ≤ 400mA
0.1
%
15
kΩ
SSR
Internal Soft Start Resistor
DMAX
Maximum Duty Cycle
ISW
Max
6.0
VULVO
IFB
Typ
Switch Current Limit
MIC2601
85
MIC2602
80
Note 5
1.2
88
Switch Saturation Voltage
ISW = 1.2A
500
Switch Leakage Current
VEN = 0V, VSW = 18V
0.01
VEN
Enable Threshold
Turn ON
IEN
Enable Pin Current
VEN = 12V
fSW
Oscillator Frequency (MIC2601)
TJ
Over-temperature Threshold
Shutdown
A
mV
5
1.5
0.3
V
20
40
µA
1.2
1.38
MHz
1.7
2
2.3
MHz
10
15
20
%
1.02
15% Over programmed VOUT (rising)
Hysteresis
µA
V
Turn OFF
Output Over-voltage Protection
%
1.7
ISW
Oscillator Frequency (MIC2602)
%
%
VSW
VOVP
nA
1
150
°C
10
°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, θ JA, and the ambient temperature, TA. The maximum allowable power dissipation will result in excessive die
temperature, and the regulator will go into thermal shutdown.
2. The device is not guaranteed to function outside its operating rating.
3. Specification for packaged product only.
4. ISD = IVIN.
5. Guaranteed by design.
June 2008
3
M9999-062508-A
Micrel, Inc.
MIC2601/2
Typical Characteristics
Quiescent Current
vs. Input Voltage
7
4.00
3.99
6
5
4
90
3.97
3.96
89
3.95
3.94
2
3.93
1
3.92
3.91
No Switching FB Pin @ 2V
8
10 12 14 16 18
INPUT VOLTAGE (V)
20
Max Duty Cycle
vs. Temperature
100
98
96
2160
94
92
1890
1620
90
88
1350
1080
86
810
84
82
EN = 20V
VIN = 20V
80
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
2.0
Switch Current Limit
vs. Input Voltage
87
EN = VIN
VIN = 12V
Switch Saturation Voltage
vs. Input Voltage
–0.1A
–0.5A
–0.9A
–1.3A
–1.7A
0
4
2.0
1.5
–0.3A
–0.7A
–1.1A
–1.5A
–0.4A
–0.8A
–1.2A
–1.6A
86
85
4
2700
2430
2160
1890
6
EN = VIN
8 10 12 14 16 18 20
INPUT VOLTAGE (V)
Switch Saturation Voltage
vs. Switch Current
–4V –5V –6V –7V –8V –9V
–10V –12V –15V –20V
1620
1350
1080
810
540
6
8 10 12 14 16 18 20
INPUT VOLTAGE (V)
VSAT
vs. Temperature
ISW=Current Limit
270
0
SWITCH CURRENT (A)
Line Regulation
18.40
18.35
18.30
18.25
1.4
18.20
1.0
1.2
1.0
0.5
18.15
ISW=850mA
ISW=500mA
0.8
0.6
4
–0.2A
–0.6A
–1.0A
–1.4A
540
270
1.8
1.6
88
3.90
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
2700
2430
Max Duty Cycle
vs. Input Voltage
91
3.98
3
0
6
Quiescent Current
vs. Temperature
EN = VIN
6
1.270
8 10 12 14 16 18 20
INPUT VOLTAGE (V)
Feedback Voltage
vs. Temperature
1.265
18.05
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
1.290
Enable Threshold ON
vs. Temperature
1.255
1.250
1.275
VIN = 12V
Load = 100mA
1.240
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
June 2008
25
6
Load = 40mA
8 10 12 14 16 18
INPUT VOLTAGE (V)
Enable Current
vs. Temperature
21
20
1.270
19
18
17
1.265
1.260
1.245
18.00
4
24
23
22
1.285
1.280
1.260
18.10
1.255
VIN = 12V
1.250
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
4
EN = 0V
16
VIN = 12V
15
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
M9999-062508-A
Micrel, Inc.
MIC2601/2
Typical Characteristics
Frequency
vs. Input Voltage
2.0
1.9
MIC2602
2.0
1.9
Frequency
vs. Temperature
MIC2602
18VOUT Efficiency
100
90
80
1.8
1.8
1.7
1.6
1.7
1.6
70
60
1.5
1.4
1.5
1.4
50
40
1.3
1.3
1.2
1.1
1.2
1.1
30
20
1.0
4
MIC2601
6 8 10 12 14 16 18 20
INPUT VOLTAGE (V)
MIC2601
1.0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
18VOUT Efficiency
100
90
0.075
12VIN
70
60
50
40
0 10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
June 2008
10
0
0 100 200 300 400 500 600 700 800
LOAD CURRENT (mA)
Thermal Derating
900
700
0.073
600
500
0.072
8VIN
12VIN
800
0.074
4.5VIN
80
Shutdown Current
vs. Temperature
8VIN
400
0.071
300
0.070 EN = 0V
VIN = 12V
0.069
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
5
200
100 VIN = 12V
VOUT = 19V
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
M9999-062508-A
Micrel, Inc.
MIC2601/2
Functional Characteristics
June 2008
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M9999-062508-A
Micrel, Inc.
MIC2601/2
Functional Diagram
VIN
VDD
FB
OVP CMP
Regulator
OVP
CL
THERMAL
UVLO
BANDGAP
EN
Bandgap
SW
OSC
EA
1.25V
S
PWM
CMP
R
SS
+
1.2 / 2MHz
Oscillator
OSC
+
Ramp
Generator
CA
PGND
AGND
Figure 1. MIC2601/2 Block Diagram
June 2008
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M9999-062508-A
Micrel, Inc.
MIC2601/2
SS
The SS pin is the soft start pin which allows the
monotonic buildup of output when the MIC2601/2 comes
up during turn on. The SS pin gives the designer the
flexibility to have a desired soft start by placing a
capacitor SS to ground. A 0.1µF capacitor is used for in
the circuit.
Functional Description
The MIC2601/2 is a constant frequency, PWM current
mode boost regulator. The block diagram is shown in
Figure 1. The MIC2601/2 is composed of an oscillator,
slope compensation ramp generator, current amplifier,
gm error amplifier, PWM generator, and a 1.2A bipolar
output transistor. The oscillator generates a 1.2/2MHz
clock. The clock’s two functions are to trigger the PWM
generator that turns on the output transistor and to reset
the slope compensation ramp generator. The current
amplifier is used to measure the 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 fed to one
of the inputs of the PWM generator.
The gm error amplifier measures the feedback voltage
through the external feedback resistors and amplifies the
error between the detected signal and the 1.25V
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.
FB
The feedback pin (FB) provides the control path to
control the output. For fixed output controller output is
directly connected to feedback (FB) pin.
SW
The switch (SW) pin connects directly to the inductor
and provides the switching current necessary to operate
in PWM mode. Due to the high speed switching and high
voltage associated with this pin, the switch node should
be routed away from sensitive nodes.
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.
AGND
Analog ground (AGND) 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.
Pin Description
VIN
VIN provides power to the MOSFETs for the switch
mode regulator section. Due to the high switching
speeds, a 2.2µF capacitor is recommended close to VIN
and the power ground (PGND) pin for bypassing. Please
refer to layout recommendations.
VDD
The VDD pin supplies the power to the internal power to
the control and reference circuitry. The VDD is powered
from VIN. A small 0.1µF capacitor is recommended for
bypassing.
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 <10µA). Also, in the off state,
the output drive is placed in a "tri-stated" condition,
where bipolar output transistor is in an “off” or nonconducting state. Do not drive the enable pin above the
supply voltage.
June 2008
8
M9999-062508-A
Micrel, Inc.
MIC2601/2
Component Selection
Inductor
Inductor selection is a balance between efficiency,
stability, cost, size, and rated current. For most
applications, a 10µH is the recommended inductor
value; it is usually a good balance between these
considerations. Large inductance values reduce the
peak-to-peak ripple current, affecting efficiency. This has
an effect of reducing both the DC losses and the
transition losses. There is also a secondary effect of an
inductor’s DC resistance (DCR). The DCR of an inductor
will be higher for more inductance in the same package
size. This is due to the longer windings required for an
increase in inductance. Since the majority of input
current (minus the MIC2601 operating current) is passed
through the inductor, higher DCR inductors will reduce
efficiency. 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:
Application Information
DC-to-DC PWM Boost Conversion
The MIC2601/2 is a constant frequency boost converter.
It operates by taking a DC input voltage and regulating a
higher DC output voltage. Figure 2 shows a typical
circuit. Boost regulation is achieved by turning on an
internal switch, which draws current through the inductor
(L1). When the switch turns off, the inductor’s magnetic
field collapses, causing the current to be discharged into
the output capacitor through an external Schottky diode
(D1). Voltage regulation is achieved through pulse-width
modulation (PWM).
L1
10µH
D1
VIN
VOUT
R1
100K
MIC2601/2
C1
2.2µF
C3
0.1µF
VIN
SW
EN
FB
VDD
SS
AGND PGND
C4
0.1µF
R2
4K
GND
C2
10µF
FRHPZ =
GND
Duty Cycle Considerations
Duty cycle refers to the switch on-to-off time ratio and
can be calculated as follows for a boost regulator:
VIN
VOUT
Output Capacitor
Output capacitor selection is also a trade-off between
performance, size, and cost. Increasing output
capacitance will lead to an improved transient response,
but also an increase in size and cost. X5R or X7R
dielectric ceramic capacitors are recommended for
designs with the MIC2601/2. Y5V values may be used,
but to offset their tolerance over temperature, more
capacitance is required.
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 overshoot slightly over 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 reduces peak current,
which in turn reduces energy transfer in each cycle.
Diode Selection
The MIC2601/2 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.
Overvoltage Protection
For the MIC2601/2 there is an over voltage protection
function. If the output voltage overshoots the set voltage
by 15% when feedback is high during input higher than
output, turn on, load transients, line transients, load
disconnection etc. the MIC2601/2 OVP ckt will shut the
switch off saving itself and other sensitive circuitry
downstream.
June 2008
2 ⋅ π ⋅ L ⋅ IO
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).
Figure 2. Typical Application Circuit
D = 1−
(D )2 ⋅ VO
Input capacitor
A minimum 2.2µF ceramic capacitor is recommended for
designing with the MIC2601/2. Increasing input
capacitance will improve performance and greater noise
9
M9999-062508-A
Micrel, Inc.
MIC2601/2
or equal to 1kΩ (R2 ≤ 1kΩ). The desired output voltage
can be calculated as follows:
immunity on the source. The input capacitor should be
as close as possible to the inductor and the MIC2601,
with short traces for good noise performance.
⎛ R1
⎞
VOUT = VREF ⋅ ⎜
+ 1⎟
R
2
⎝
⎠
Feedback Resistors
The MIC2601/2 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. The R2 resistor value must be less than
June 2008
where VREF is equal to 1.25V.
10
M9999-062508-A
Micrel, Inc.
MIC2601/2
D1
B360A
L1
10µH
1
2
2
C4
4.7µF/50V
U1 MIC2601_YML
J2
GND
J3
EN
3
R3
10k
2
VIN
SW
EN
FB
VDD
SS
4
C2
0.1µF/50V
PGND
C1
2.2µF/16V
7
C5
4.7µF/50V
R1
7.15k
6
R2
5
C3
0.1µF/50V
8
1
AGND
J1
VIN 12V
J4
VO 18V
1
J5
GND
Bill of Materials
Item
C1
Part Number
GRM21BR71C225KA12L
Murata
0805YC225MAT
AVX
(2)
Vishay(3)
06035C104MAT
AVX(2)
GRM188R71C104KA01D
GRM31CR71H475KA12L
SS3P6-E3
D1
B360A
Qty.
Capacitor, 2.2µF, 16V, X7R, Size 0805
1
Capacitor, 0.1µF, 50V, X7R, Size 0603
2
(1)
Capacitor, 0.1µF, 16V, X7R, Size 0603
(1)
Capacitor, 4.71µF, 50V, X7R, Size 1206
2
3A, 60V Schottky Diode
1
Murata
Murata
Vishay(3)
Diodes
Description
(1)
VJ0603Y104KXAAT
C2, C3
C4, C5
Manufacturer
(4)
L1
LQH55DN100M03
Murata(1)
10µH, 1700mA
1
R1
CRCW06037K15FKEA
Vishay Dale(3)
Resistor, 7.15k, 1%, 1/16W, Size 0603
1
CRCW06034990FKEA
(3)
R2
R3
CRCW060310K0FKEA
U1
MIC2601-YML
Vishay Dale
Resistor, 499Ω, 1%, 1/16W, Size 0603
1
(3)
Resistor, 10k, 1%, 1/16W, Size 0603
1
(5)
1.2A, 1.2MHz Wide Range Integrated Switch Boost
Regulator
1
Vishay Dale
Micrel, Inc.
Notes:
1. Murata: www.murata.com
2. AVX: www.avx.com
3. Vishay: www.vishay.com
4. Murata: www.diodes.com
5. Micrel, Inc.: www.micrel.com
June 2008
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M9999-062508-A
Micrel, Inc.
MIC2601/2
PCB Layout Recommendations
Top Layer
Bottom Layer
June 2008
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M9999-062508-A
Micrel, Inc.
MIC2601/2
Package Information
8-Pin 2mm x 2mm 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.
© 2008 Micrel, Incorporated.
June 2008
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M9999-062508-A