Micrel MIC2290BML 2mm ã 2mm pwm boost regulator with internal schotty diode Datasheet

MIC2290
Micrel
MIC2290
2mm × 2mm PWM Boost Regulator with
Internal Schotty Diode
General Description
Features
The MIC2290 is a 1.2MHz , PWM, boost-switching regulator
housed in the small size 2mm × 2mm MLF™-8 package. The
MIC2290 features an internal Schottky diode that reduces
circuit board area and total solution cost. High power density
is achieved with the MIC2290’s internal 34V/0.5A switch,
allowing it to power large loads in a tiny footprint.
The MIC2290 implements a constant frequency 1.2MHz
PWM control scheme. The high frequency operation saves
board space by reducing external component sizes. The
fixed frequency PWM topology also reduces switching noise
and ripple to the input power source.
The MIC2290’s wide 2.5V to 10V input voltage allows direct
operation from 3- to 4-cell NiCad/NiMH/Alkaline batteries, 1and 2-cell Li Ion batteries, as well as fixed 3.3V and 5V
systems.
The MIC2290 is available in a low-profile 2mm × 2mm
8-pin MLF™ leadless package and operates from a junction
temperature range of –40°C to +125°C.
All support documentation can be found on Micrel’s web
site at www.micrel.com.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Internal Schottky diode
2.5V to 10V input voltage
Output voltage adjustable to 34V
Over 500mA switch current
1.2MHz PWM operation
Stable with ceramic capacitors
<1% line and load regulation
Low input and output ripple
<1µA shutdown current
UVLO
Output overvoltage protection
Over temperature protection
2mm × 2mm 8-pin MLF™ package
–40°C to +125°C junction temperature range
Applications
•
•
•
•
•
Organic EL power supply
TFT LCD bias supply
12V DSL power supply
CCD bias supply
SEPIC converters
Typical Application
VOUT
12V
L1
10µH
VIN
85
C1
1µF
EN
SW
OUT
FB
7
R1
1
C2
10µF
6
GND
4, 8
EFFICIENCY (%)
Li Ion
Battery
3
VIN
VIN = 4.2V
80
MIC2290BML
2
12VOUT Efficiency
75
70
VIN = 3.2V
VIN = 3.6V
65
R2
60
0
0.02 0.04 0.06 0.08
LOAD CURRENT (A)
0.1
Simple 12V Boost Regulator
MicroLeadFrame and MLF are trademarks of Amkor Technology, Inc.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
August 2004
1
M9999-081104
MIC2290
Micrel
Ordering Information
Part Number
Marking
Code
Output
Voltage
Overvoltage
Protection
Junction
Temp. Range
Package
Lead Finish
MIC2290BML
SRC
Adjustable
34V
–40°C to 125°C
2×2 8-pin MLF™
Standard
MIC2290YML
SRC
Adjustable
34V
–40°C to 125°C
2×2 8-pin MLF™
Lead Free
Pin Configuration
OUT
1
8
PGND
VIN
2
7
SW
EN
3
6
FB
AGND
4
5
NC
8-Pin MLF™ (ML)
(Top View)
Fused Lead Frame
Pin Description
Pin Number
Pin Name
Pin Function
1
OUT
Output pin (Output): Output voltage. Connect to FB resistor divider. This pin
has an internal 34V output overvoltage clamp. See “Block Diagram” and
“Applications” section for more information.
2
VIN
Supply (Input): 2.5V to 10V input voltage.
3
EN
Enable (Input): Logic high enables regulator. Logic low shuts down regulator.
4
AGND
5
NC
No connect (no internal connection to die).
6
FB
Feedback (Input): Output voltage sense node. Connect feedback resistor
Analog ground.

network to this pin. VOUT = 1.24V 1+
7
SW
8
PGND
EP
GND
M9999-081104
R1

R2 
Switch node (Input): Internal power Bipolar collector.
Power ground.
Ground (Return): Exposed backside pad.
2
August 2004
MIC2290
Micrel
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) ..................................................... 12V
Switch Voltage (VSW) ..................................... –0.3V to 34V
Enable Pin Voltage (VEN) ................................... –0.3 to VIN
FB Voltage (VFB) ............................................................. 6V
Switch Current (ISW) ....................................................... 2A
Storage Temperature (TS) ....................... –65°C to +150°C
ESD Rating(3) ................................................................ 2kV
Supply Voltage (VIN) ........................................ 2.5V to 10V
Junction Temperature Range (TJ) ........... –40°C to +125°C
Package Thermal Impedance
2mm × 2mm MLF™ (θJA) .................................... 93°C/W
Electrical Characteristics(4)
TA = 25°C, VIN = VEN = 3.6V, VOUT = 10V, IOUT = 20mA, unless otherwise noted. Bold values indicate –40°C ≤ TJ ≤ ±125°C.
Symbol
Parameter
Condition
Min
VIN
Supply Voltage Range
2.5
VUVLO
Undervoltage Lockout
1.8
IVIN
Quiescent Current
VFB = 2V, (not switching)
0V(5)
Typ
Max
Units
10
V
2.1
2.4
V
2.5
5
mA
0.2
1
µA
1.24
1.252
1.265
V
V
ISD
Shutdown Current
VEN =
VFB
Feedback Voltage
(±1%)
(±2%) (Over Temp)
IFB
Feedback Input Current
VFB = 1.24V
Line Regulation
3V ≤ VIN ≤ 5V
0.1
1
%
Load Regulation
5mA ≤ IOUT ≤ 20mA
0.2
1
%
DMAX
Maximum Duty Cycle
ISW
Switch Current Limit
VSW
Switch Saturation Voltage
ISW
VEN
1.227
1.215
–450
85
nA
90
%
0.75
A
ISW = 0.5A
450
mV
Switch Leakage Current
VEN = 0V, VSW = 10V
0.01
Enable Threshold
Turn on
Turn off
5
µA
0.4
V
V
20
40
µA
1.2
1.35
MHz
0.8
1
V
4
µA
34
V
1.5
IEN
Enable Pin Current
VEN = 10V
fSW
Oscillator Frequency
VD
Schottky Forward Drop
ID = 150mA
IRD
Schottky Leakage Current
VR = 30V
VOVP
Overvoltage Protection
(nominal voltage)
TJ
Overtemperature
Threshold Shutdown
Hysteresis
1.05
30
32
150
10
°C
°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, θJA, 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. This device is not guaranteed to operate beyond its specified operating rating.
3. IC devices are inherently ESD sensitive. Handling precautions required. Human body model rating: 1.5K in series with 100pF.
4. Specification for packaged product only.
5. ISD = IVIN.
August 2004
3
M9999-081104
MIC2290
Micrel
Typical Characteristics
70
VIN = 3.6V
65
60
VIN = 3.3V
55
50
0
0.9
25
50
75
100
OUTPUT CURRENT (mA)
FEEDBACK VOLTAGE (V)
75
12.08
12.06
12.04
12.02
12
11.98
11.96
11.94
11.92
11.9
0
Current Limit
vs. Supply Voltage
1.0
VIN = 3.6V
20
40
60
LOAD (mA)
CURRENT LIMIT (A)
CURRENT LIMIT (A)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.8
0.6
0.4
0.2
0.1
700
600
500
400
300
200
VIN = 3.6V
100
0
0
100 200 300 400 500
SWITCH CURRENT (mA)
90
88
86
84
4
5.5
7
8.5
SUPPLY VOLTAGE (V)
10
1.25
1.24
1.24
1.23
1.23
Switch Saturation Voltage
vs. Temperature
540
Switch Saturation
vs. Supply Voltage
530
520
510
500
490
480
470
460
450
2.5
1.4
ISW = 500mA
4
5.5
7
8.5
SUPPLY VOLTAGE (V)
10
Frequency
vs. Temperature
1.35
600
500
400
300
200
VIN = 3.6V
I = 500mA
100
SW
1.3
1.25
1.2
1.15
1.1
1.05
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
99
94
92
M9999-081104
700
Maximum Duty Cycle
vs. Supply Voltage
98
96
82
80
2.5
SWITCH SATURATION VOLTAGE (mV)
10
Switch Saturation
vs. Current
100
MAXIMUM DUTY CYCLE (%)
4
5.5
7
8.5
SUPPLY VOLTAGE (V)
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
MAXIMUM DUTY CYCLE (%)
SWITCH SATURATION VOLTAGE (mV)
0
2.5
1.25
1.22
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
80
Current Limit
vs. Temperature
Feedback Voltage
vs. Temperature
1.26
SWITCH SATURATION VOLTAGE (mV)
VIN = 4.2V
80
1.26
FREQUENCY (MHz)
EFFICIENCY (%)
85
Load Regulation
12.1
1
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Maximum Duty Cycle
vs. Temperature
97
95
93
91
89
VIN = 3.6V
87
85
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
4
700
FEEDBACK CURRENT (nA)
Efficiency at VOUT = 12V
OUTPUT VOLTAGE (V)
90
FB Pin Current
vs. Temperature
600
500
400
300
200
100
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
August 2004
MIC2290
700
1.28
1.26
1.24
1.22
1.2
1.18
1.16
1.14
1.12
1.1
2.5
August 2004
4
5.5
7
8.5
SUPPLY VOLTAGE (V)
10
Schottky Diode Leakage
vs. Temperature
600
500
400
300
200
100
VR = 15V
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
5
100
REVERSE CURRENT (nA)
Enable Threshold
vs. Supply Voltage
FEEDBACK CURRENT (nA)
ENABLE THRESHOLD (V)
1.3
Micrel
Schottky Reverse Leakage
vs. Reverse Voltage
90
80
70
60
50
40
30
20
10
0
0
5 10 15 20 25 30
REVERSE VOLTAGE (V)
35
M9999-081104
MIC2290
Micrel
Function Characteristics
Enable Characteristics
3.6VIN
12VOUT
150mA Load
Load Transient Response
Switching Waveforms
6
SWITCH SATURATION
(5V/div)
3.6VIN
12VOUT
COUT = 10µF
OUTPUT VOLTAGE
(50mV/div)
Time (400µs/div)
Time (400µs/div)
M9999-081104
12VOUT
150mA Load
Time (400µs/div)
INDUCTOR CURRENT
(500mA/div)
LOAD CURRENT
OUTPUT VOLTAGE
(50mA/div)
(100mV/div) AC-Coupled
ENABLE VOLTAGE
(2V/div)
OUTPUT VOLTAGE
(5V/div)
INPUT VOLTAGE OUTPUT VOLTAGE
(2V/div)
(100mV/div) AC-Coupled
Line Transient Response
Output Voltage
Inductor Current
(10µH)
3.6VIN
12VOUT
60mA
VSW
Time (400ns/div)
August 2004
MIC2290
Micrel
Functional Diagram
VIN
FB
OUT
EN
OVP
SW
PWM
Generator
gm
VREF
1.24V
Σ
1.2MHz
Oscillator
CA
Ramp
Generator
GND
Figure 1. MIC2290 Block Diagram
The gm error amplifier measures the feedback voltage through
the external feedback resistors and amplifies the error between the detected signal and the 1.24V 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.
Functional Description
The MIC2290 is a constant frequency, PWM current mode
boost regulator. The block diagram is shown in Figure 1. The
MIC2290 is composed of an oscillator, slope compensation
ramp generator, current amplifier, gm error amplifier, PWM
generator, and a 0.5A bipolar output transistor. The oscillator
generates a 1.2MHz 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.
August 2004
7
M9999-081104
MIC2290
Micrel
Applications Information
Component Selection
DC-to-DC PWM Boost Conversion
The MIC2290 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
internal Schottky diode (D1). Voltage regulation is achieved
through pulse-width modulation (PWM).
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 MIC2290 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:
L1
10µH
VIN
VOUT
MIC2290BML
VIN
C1
2.2µF
SW
OUT
EN
C2
10µF
FB
GND
GND
R1
R2
GND
Figure 2. Typical Application Circuit
Duty Cycle Considerations
Duty cycle refers to the switch on-to-off time ratio and can be
calculated as follows for a boost regulator:
D = 1−
Frhpz =
2
VOUT × L × IOUT × 2π
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).
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 MIC2290. Y5V values
may be used, but to offset their tolerance over temperature,
more capacitance is required. The following table shows the
recommended ceramic (X5R) output capacitor value vs.
output voltage.
VIN
VOUT
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.
Overvoltage Protection
For the MLF™ package option, there is an overvoltage
protection function. If the feedback resistors are disconnected from the circuit or the feedback pin is shorted to
ground, the feedback pin will fall to ground potential. This will
cause the MIC2290 to switch at full duty cycle in an attempt
to maintain the feedback voltage. As a result, the output
voltage will climb out of control. This may cause the switch
node voltage to exceed its maximum voltage rating, possibly
damaging the IC and the external components. To ensure the
highest level of protection, the MIC2290 OVP pin will shut the
switch off when an overvoltage condition is detected, saving
itself and other sensitive circuitry downstream.
M9999-081104
VIN
Output Voltage Recomended Output Capacitance
<6V
22µF
<16V
10µF
<34V
4.7µF
Table 1. Output Capacitor Selection
Input capacitor
A minimum 1µF ceramic capacitor is recommended for
designing with the MIC2290. Increasing input capacitance
will improve performance and greater noise immunity on the
source. The input capacitor should be as close as possible to
the inductor and the MIC2290, with short traces for good
noise performance.
8
August 2004
MIC2290
Micrel
Feedback Resistors
The MIC2290 utilizes a feedback pin to compare the output
to an internal reference. The output voltage is adjusted by
selecting the appropriate feedback resistor values. The desired output voltage can be calculated as follows:
 R1 
VOUT = VREF × 
+ 1
 R2 
where VREF is equal to 1.24V.
August 2004
9
M9999-081104
MIC2290
Micrel
Application Circuits
L1
4.7µH
VIN
3.3V
L1
10µH
VIN
3V to 4.2V
VOUT
5V @ 180mA
MIC2290BML
MIC2290BML
C1
2.2µF
6.3V
SW
VIN
R1
5.62k
FB
GND
EN
FB
GND
GND
R1
54.9k
OUT
GND
R2
100k
GND
SW
VIN
C1
2.2µF
6.3V
C2
10µF
6.3V
OUT
EN
VOUT
15V @ 45mA
R2
5k
C2
10µF
16V
GND
C1
2.2µF, 6.3V, 0805 X5R Ceramic Capacitor
08056D475MAT
AVX
C1
2.2µF, 6.3V, 0603 X5R Ceramic Capacitor
06036D225MAT
AVX
C2
10µF, 6.3V, 0805 X5R Ceramic Capacitor
08056D106MAT
AVX
C2
10µF, 16V, 1206 X5R Ceramic Capacitor
1206YD106MAT
AVX
L1
4.7µH, 450mA Inductor
LQH32CN4R7N11
Murata
L1
10µH, 450mA Inductor
LQH32CN100K11
Murata
Figure 6. 3.3VIN – 4.2VIN to 15VOUT @ 45mA
Figure 3. 3.3VIN to 5VOUT @ 180mA
L1
10µH
VIN
3V to 4.2V
L1
10µH
VIN
5V
VOUT
9V @ 80mA
MIC2290BML
MIC2290BML
C1
2.2µF
6.3V
SW
VIN
R1
31.6k
OUT
EN
FB
GND
SW
VIN
C1
2.2µF
6.3V
C2
10µF
16V
EN
FB
R2
5k
GND
GND
R1
31.6k
OUT
GND
R2
5k
GND
VOUT
9V @ 160mA
C2
10µF
16V
GND
C1
2.2µF, 6.3V, 0603 X5R Ceramic Capacitor
06036D225MAT
AVX
C1
2.2µF, 6.3V, 0603 X5R Ceramic Capacitor
06036D225MAT
AVX
C2
10µF, 16V, 1206 X5R Ceramic Capacitor
1206YD106MAT
AVX
C2
10µF, 16V, 1206 X5R Ceramic Capacitor
1206YD106MAT
AVX
L1
10µH, 450mA Inductor
LQH32CN100K11
Murata
L1
10µH, 450mA Inductor
LQH32CN100K11
Murata
Figure 7. 5VIN to 9VOUT @ 160mA
Figure 4. 3.3VIN – 4.2VIN to 9VOUT @ 80mA
L1
10µH
VIN
3V to 4.2V
L1
10µH
VIN
5V
VOUT
12V @ 50mA
MIC2290BML
MIC2290BML
C1
2.2µF
6.3V
VIN
SW
R1
43.2k
OUT
EN
FB
GND
GND
VOUT
12V @ 110mA
R2
5k
C1
2.2µF
6.3V
C2
10µF
16V
VIN
SW
OUT
EN
FB
GND
GND
GND
R1
43.2k
R2
5k
C2
10µF
16V
GND
C1
2.2µF, 6.3V, 0603 X5R Ceramic Capacitor
06036D225MAT
AVX
C1
2.2µF, 6.3V, 0603 X5R Ceramic Capacitor
06036D225MAT
AVX
C2
10µF, 16V, 1206 X5R Ceramic Capacitor
1206YD106MAT
AVX
C2
10µF, 16V, 1206 X5R Ceramic Capacitor
1206YD106MAT
AVX
L1
10µH, 450mA Inductor
LQH32CN100K11
Murata
L1
10µH, 450mA Inductor
LQH32CN100K11
Murata
Figure 8. 5VIN to 12VOUT @ 110mA
Figure 5. 3.3VIN – 4.2VIN to 12VOUT @ 50mA
M9999-081104
10
August 2004
MIC2290
Micrel
L1
10µH
VIN
5V
VOUT
24V @ 40mA
MIC2290BML
C1
2.2µF
6.3V
VIN
SW
R1
18.2k
OUT
EN
FB
GND
GND
R2
1k
C2
4.7µF
25V
GND
C1
2.2µF, 6.3V, 0603 X5R Ceramic Capacitor
06036D225MAT
AVX
C2
4.7µF, 25V, 1206 X5R Ceramic Capacitor
12063D475MAT
AVX
L1
10µH, 450mA Inductor
LQH32CN100K11
Murata
Figure 9. 5VIN to 24VOUT @ 40mA
August 2004
11
M9999-081104
MIC2290
Micrel
Package Information
8-Pin MLF™ (ML)
MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
+ 1 (408) 944-0800
FAX
USA
+ 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2004 Micrel, Incorporated.
M9999-081104
12
August 2004
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