MP3412EJ-LF [MPS]
Switching Regulator, Current-mode, 1000kHz Switching Freq-Max, PDSO6, TSOT-23, 6 PIN;
| 型号： | MP3412EJ-LF |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | Switching Regulator, Current-mode, 1000kHz Switching Freq-Max, PDSO6, TSOT-23, 6 PIN 驱动 光电二极管 接口集成电路 |
| 文件： | 总12页 (文件大小：283K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MP3412
1.1A, 1MHz Synchronous Boost
WLED Driver with Output Disconnect
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP3412 is a synchronous, fixed frequency,
high efficiency step-up WLED driver with true
output load disconnect function in a low profile
6-lead Thin-SOT23 package.
Input Range: 0.8V to 4.4V
Output Range: 2.5V to 5.0V
0.8V Low Start-Up Voltage
Internal Power MOSFET and Synchronous
Rectifier
1MHz Fixed Switching Frequency
Current Mode Control with Internal
Compensation
The MP3412 can startup from an input voltage as
low as 0.8V and provides in-rush current limiting
as well as output short circuit protection. The
open load protection is also integrated
Up to 96% Efficiency
A switching frequency of 1MHz minimizes overall
solution footprint by allowing the use of tiny, low
profile inductors and ceramic capacitors. Current
mode PWM control with internal compensation
reduces external parts, thereby saving critical
board space.
<1µA Shutdown Current
Tiny External Components
True Output Load Disconnect
Inrush Current Limiting and Internal Soft-
Start
Open-Load Protection
Short-Circuit Protection
Available in TSOT23-6 Package
The device also features low shutdown current of
under 1µA. The true output disconnect feature
allows the output to be completely discharged in
shutdown. It also limits the inrush of current
during start-up, minimizing surge current seen by
the input supply.
APPLICATION
General LED Illuminations
Cellular Phones
Digital Cameras
Handheld Instruments
Wireless Handsets
GPS Receivers
The MP3412 is available in 6-pin thin SOT23
package.
“Monolithic Power Systems”, “MPS”, and “The Future of Analog IC
Technology” are Registered Trademarks of Monolithic Power Systems, Inc.
TYPICAL APPLICATION
Efficiency
100
95
Boost Mode
90
LDO Mode
85
80
75
I
=200mA
o
70
65
60
55
50
I
=80mA
o
0
1
2
3
4
5
V
(V)
IN
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
1
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
ORDERING INFORMATION
Part Number*
Package
Top Marking
Free Air Temperature (TA)
MP3412EJ
TSOT23-6
7Q
–20C to +85C
* For Tape & Reel, add suffix –Z (e.g. MP3412EJ–Z).
For RoHS Compliant Packaging, add suffix –LF (e.g. MP3412EJ–LF–Z)
PACKAGE REFERENCE
TOP VIEW
SW
GND
FB
1
2
3
6
5
4
IN
OUT
EN
Thermal Resistance (4)
TSOT23-6 ..............................220 .... 110..C/W
θJA
θJC
ABSOLUTE MAXIMUM RATINGS (1)
IN Pin.............................................-0.3V to 4.6V
All other Pins..................................-0.3V to 6.5V
Continuous Power Dissipation (TA = +25°C) (2)
................................................................. 0.56W
Junction Temperature...............................150C
Lead Temperature ....................................260C
Storage Temperature............... -65C to +150C
Recommended Operating Conditions (3)
Input Supply Voltage VIN .................0.8V to 4.4V
Output Voltage VOUT........................2.5V to 5.0V
Operating JuncT. TemP. (TJ)... -20C to +125C
Notes:
1) Exceeding these ratings may damage the device.
2) 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 continuous power dissipation at
any ambient temperature is calculated by PD(MAX)=(TJ(MAX)-
TA)/θJA. Exceeding the maximum allowable power dissipation
will cause excessive die temperature, and the regulator will go
into thermal shutdown. Internal thermal shutdown circuitry
protects the device from permanent damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
2
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
ELECTRICAL CHARACTERISTICS
VIN = VEN=1.2V, ILED = 200mA, TA = +25C, unless otherwise noted.
Parameters
Symbol Condition
Min
Typ Max Units
Minimum Startup Voltage
Maximum Input Voltage
Output Voltage Range
VST MIN
VIN MAX
VOUT
VOUT=0V
0.62 0.72 0.82
4.4
V
V
V
2.5
5
VEN=VIN=1.2V, VFB=0.3V,
Measured on OUT pin
Supply Current (Quiescent)
Supply Current (Shutdown)
IO
380
600
µA
µA
VEN=VOUT=0V, VIN=3.3V
Measured on IN pin
ISD
1
Operation Frequency
Maximum Duty Cycle
Feedback Voltage
EN Low Threshold
EN High Threshold
fSW
DMAX
0.90 1.05 1.20 MHz
87
190
0.4
%
mV
V
VFB
200
210
VEN LOW
VEN Falling
VEN HIGH VEN Rising
0.62
V
VEN=6V
IEN
16
0
nA
nA
mΩ
EN Input Current
VEN=0V
NMOS On Resistance (5)
RNMOS ON
RPMOS_ON
336
Synchronous Switch On
Resistance (5)
405
mΩ
VOUT=2V, Start-up period
0.5
1.1
A
A
NMOS Current Limit (5)
ILIMIT
VOUT=3.3V
VSW Rising
Open loop
Over Voltage Protection
Threshold
VOVP
TSS
4.8
5.1
5.5
V
Soft-Start Time
Thermal Shutdown (5)
200
150
µs
C
Notes:
5) Guaranteed by design.
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
3
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
PIN FUNCTIONS
Pin #
Name Pin Function
Power Switch Output. SW is the connection node of the internal NMOS switch and
synchronous switch. Connect the power inductor to SW.
1
2
3
4
SW
GND
FB
Ground.
Feedback Input to the Error Amplifier. Connect the anode of LED to this pin. The feedback
reference voltage is 0.2V
EN
Enable Control Input.
Step-up Converter Output. OUT is the drain of the Internal Synchronous Rectifier MOSFET.
Connect the LED anode to this pin. OUT pin is completely disconnected from IN pin when
EN is low due to the output disconnect feature.
5
6
OUT
IN
Battery Supply Input. Must be locally bypassed
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
4
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = VEN = 1.8V, ILED = 200mA, One WLED, unless otherwise noted.
PWM Dimming Duty vs.
WLED Current
V
IN
vs. Efficiency
f
=200Hz
PWM
250
200
150
100
50
100
95
90
85
80
75
70
65
60
55
50
Boost Mode
LDO Mode
I
=200mA
o
I
=80mA
o
0
0
1
2
3
4
5
0
20
40
60
80
100
V
(V)
PWM DIMMING DUTY (%)
IN
Steady State (Boost Mode)
Steady State (LDO Mode)
Steady State (Boost Mode)
V
=V =0.8V, I
IN EN
=80mA
LED
V
=V =4.4V, I
IN EN
=200mA
LED
V
=V =1.8V, I
IN EN
=200mA
LED
V
SW
V
SW
2V/div.
V
SW
2V/div.
2V/div.
V
/AC
V
/AC
OUT
V
/AC
OUT
OUT
100mV/div.
50mV/div.
100mV/div.
V
FB
V
V
FB
FB
50mV/div.
INDUCTOR
200mA/div.
50mV/div.
INDUCTOR
100mA/div.
50mV/div.
INDUCTOR
200mA/div.
I
I
I
1us/div.
1us/div.
1us/div.
Enable Shutdown
Enable Startup
Enable Startup
V
=V =1.8V, I
IN EN
=200mA
LED
V
=V =1.8V, I
IN EN
=200mA
LED
V
=V =0.8V, I
IN EN
=80mA
LED
V
SW
V
V
SW
SW
2V/div.
2V/div.
2V/div.
V
EN
V
V
EN
EN
1V/div.
2V/div.
2V/div.
V
OUT
V
V
OUT
OUT
2V/div.
2V/div.
2V/div.
I
I
LED
LED
I
LED
100mA/div.
100mA/div.
50mA/div.
100us/div.
40us/div.
20us/div.
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
5
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = VEN = 1.8V, ILED = 200mA, One WLED, unless otherwise noted.
Open Load Protection
PWM Dimming
Short LED Protection
Remove LED at working
f
=200Hz, DPWM=50%
Short start up then recover
PWM
V
SW
V
SW
2V/div.
2V/div.
V
SW
2V/div.
PWM
2V/div.
I
INDUCTOR
200mA/div.
V
OUT
V
OUT
2V/div.
V
2V/div.
OUT
2V/div.
I
I
I
LED
LED
LED
100mA/div.
200mA/div.
100mA/div.
2ms/div.
10us/div.
100ms/div.
Short OUT to GND Protection
Short OUT to GND Protection
Short LED Protection
Short start up then recover
Short at working then recover
Short at working then recover
V
V
SW
V
SW
SW
2V/div.
2V/div.
2V/div.
I
I
INDUCTOR
200mA/div.
INDUCTOR
I
INDUCTOR
200mA/div.
200mA/div.
V
V
OUT
V
OUT
OUT
2V/div.
2V/div.
2V/div.
I
I
LED
I
LED
LED
200mA/div.
200mA/div.
200mA/div.
100ms/div.
100ms/div.
100ms/div.
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
6
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
FUNCTION BLOCK DIAGRAM
L
Battery
0.8V~4.4V
CIN
IN
SW
Vin
+
-
Vout Good
2.3V
Body
Control
OUT
Start-up
OSC
A
B
Driver
Control
Control
Logic
+
-
Slope
Compensation
Oscillator
Current Sense
Amplifier
COUT
PWM
Comparator
+
-
FB
-
-
EA
+
0.2V
260kꢀ
EN
Enable
Control
RSENSE
2.5pF
44pF
GND
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
7
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
OPERATION
The MP3412 is a 1MHz, synchronous boost
WLED driver in a 6-lead TSOT-23 package. It is
able to operate from an input voltage below 1V.
Fixed frequency PWM current mode control is
applied to regulate the WLED current. Low
RDS(ON) internal MOSFET switches enable the
device to maintain high efficiency over a wide
range of WLED current.
Lossless current sensor converts the NMOS
switch current signal to a voltage signal, and sum
with the internal slope compensation signal. The
summed signal is compared with the error
amplifier output to generate a PWM signal to
control the switch. The switch peak current is
limited to 1.1A independent of input or output
voltage. The switch current signal is blanked for
60ns after the switch is on to enhance noise
rejection.
Low Voltage Start-Up
The MP3412 includes an independent start-up
oscillator designed to start up at input voltages of
0.8V typically. The frequency and duty cycle of
the start-up oscillator are internally set to 250kHz
and 70% respectively. In this mode, the IC
operates completely open-loop and the current
limit is also set internally to 1.1A. Once the output
voltage exceeds 2.3V, the start-up circuitry is
disabled and normal close-loop PWM operation
is initiated. In this mode, the MP3412 is biased
by VOUT instead of VIN. This feature makes the
chip can work normally when VIN drops to 0.5V.
Soft-start and inrush current limiting are provided
during start-up process.
Synchronous Rectifier
The PMOS synchronous rectifier is enabled
when VOUT > (VIN+0.1V) and the FB pin is
>130mV.
Thermal Shutdown
An internal temperature monitor will start to
reduce the peak current limit if the die
temperature exceeds 125ºC. And if the die
temperature continues to rise and reaches
150ºC, the part will be thermal shutdown. All
switches would be off and the soft-start capacitor
would be discharged completely. The chip will be
enabled again if the die temperature drops down.
Soft-Start
Output Disconnect and Inrush Limiting
The MP3412 realizes soft-start by charging an
internal capacitor with a current source. The
voltage on this capacitor slowly ramps the peak
inductor current from 300mA to 1.1A. The soft-
start time is typically 200µs. But this time varies
greatly with load current, output voltage and input
voltage. The soft-start capacitor is discharged
completely when the chip is shut down, and
discharged partially when the output is short
circuit.
The MP3412 is designed to allow true output
disconnect by eliminating body diode conduction
of the internal PMOS rectifier. This makes VOUT
to decrease to zero volts during shutdown. This
feature is also convenient to limit the inrush
current during start up.
VOUT < VIN Operation
The MP3412 will maintain current regulation
even if the input voltage is above the output
voltage. Since the PMOS no longer acts as a low
impedance switch in this mode, there will be
more power dissipation in IC, and the efficiency
in this mode is low. The maximum output current
should be limited in order to maintain an
acceptable junction temperature.
Oscillator
The frequency of operation is internally set to
1MHz.
Error Amp
The error amplifier is an internally compensated
transconductance
type
amplifier.
Its
transconductance is about 33 microsiemens. The
current sensing resistor RSENSE feeds back the
WLED current signal to FB pin. And the voltage
at the FB is compared to the internal 200mV
reference voltage to generate an error signal at
the output of error amplifier.
Switch Current Sensing
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
8
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
Open Load Protection
Open load protection will shut down the MP3412.
If the WLED is fail, the feedback voltage will
always be zero, and the part will run at maximum
duty cycle. The output voltage will be boosted
very high. When the output voltage of SW
exceeds 5.1V, the MP3412 will be shut down.
And it does not switch again until the power is
recycled.
Short Circuit Protection
Unlike most boost converters, the MP3412 allows
their output to be short circuit due to the output
disconnect feature. The device incorporates
internal features such as current limit function,
thermal regulation and thermal shutdown to
protect the chip from burn out which is caused by
an excessive overload or short circuit. In the
event of a short circuit, the internal soft-star
capacitor gets partially discharged. This, in turn,
decreased the current limit threshold from 1.1A to
a small value. In addition to this, a thermal
regulation circuit starts to work to decrease the
current limit farther if the die temperature rises
above 125ºC. And if the die temperature still rises
and reaches 150ºC, the chip will be shut down.
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
9
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
APPLICATION INFORMATION
Setting the LED Current
Layout Considerations
The regulated LED current is identical and set
through the current sensing resistor through the
use of the equation:
Careful attention must be paid to the PCB board
layout and components placement. Proper layout
of the high frequency switching path is critical to
prevent noise and electromagnetic interference
problems. The loop of MP3412 SW to GND pin,
SW to OUT pin, and output capacitor is flowing
with high frequency pulse current. It must be as
short as possible. The IN and OUT pin are both
the power supply input for the internal MOSFET
switch gate driver and the internal control
circuitry. They must be locally bypassed.
ILED = 0.2V / RSENSE
For RSENSE=1Ω, the LED current is set to about
200mA.
PWM Dimming
Apply a typical 200Hz square waveform to the
EN pin to implement PWM dimming of the LEDs.
The minimum recommended amplitude of the
PWM signal is 0.8V.
Output
Capacitor
Selecting the Inductor
A 3.3μH to 10µH inductor with a DC current
rating of at least 40% higher than the maximum
input current is recommended for most
applications at wide input range. For highest
efficiency, the inductor’s DC resistance should be
as small as possible.
OUT
SW
GND
Selecting the Input Capacitor
The input capacitor reduces the surge current
drawn from the input supply and the switching
noise from the device. The input capacitor
impedance at the switching frequency should be
less than the input source impedance to prevent
high frequency switching current from passing
through the input. Ceramic capacitors with X5R
or X7R dielectrics are highly recommended
because of their low ESR and small temperature
coefficients. For most applications, a 4.7μF or
10μF capacitor is sufficient.
Figure 1- Layout Consideration
Selecting the Output Capacitor
The output capacitor keeps the output voltage
ripple small and ensures feedback loop stability.
The output capacitor impedance should be low at
the switching frequency. Ceramic capacitors with
X7R dielectrics are recommended for their low
ESR characteristics. For most applications, a
2.2μF ceramic capacitor is sufficient.
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
10
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
TYPICAL APPLICATION CIRCUIT
Figure 2—Step-up White LED Driver Application
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
11
MP3412 - 1.1A, 1MHz SYNCHRONOUS BOOST WLED DRIVER WITH OUTPUT DISCONNECT
PACKAGE INFORMATION
TSOT23-6
0.95
BSC
0.60
TYP
2.80
3.00
6
4
1.20
TYP
1.50
1.70
2.60
TYP
2.60
3.00
1
3
TOP VIEW
RECOMMENDED LAND PATTERN
0.84
0.90
1.00 MAX
SEATING PLANE
0.09
0.20
0.30
0.50
0.00
0.10
0.95 BSC
SEE DETAIL "A"
FRONT VIEW
SIDE VIEW
NOTE:
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,
PROTRUSION OR GATE BURR.
GAUGE PLANE
0.25 BSC
3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH
OR PROTRUSION.
0.30
0.50
4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING)
SHALL BE 0.10 MILLIMETERS MAX.
0o-8o
5) DRAWING CONFORMS TO JEDEC MO-193, VARIATION AA.
6) DRAWING IS NOT TO SCALE.
DETAIL “A”
NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third
party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not
assume any legal responsibility for any said applications.
MP3412 Rev. 0.9
9/7/2011
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.
12
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