MPS MP3399 12-string, cascading white led driver for extending led channel Datasheet

MP3399
The Future of Analog IC Technology
12-String, Cascading White LED Driver
For Extending LED Channels
DESCRIPTION
FEATURES
The MP3399 is a step-up controller with 12channel current sources designed for driving
the WLED arrays for large size LCD panel
backlighting applications.
The MP3399 is
flexible for extending LED channels with two or
more MP3399s in parallel while operating from
a single Inductor power source.
•
•
The MP3399 uses current mode, fixed frequency
architecture. The switching frequency is
programmable by an external frequency setting
resistor. It drives an external MOSFET to boost
up the output voltage from a 5V to 28V input
supply. The MP3399 regulates the current in
each LED string to the programmed value set by
an external current setting resistor.
•
•
•
•
•
•
•
The MP3399 applies 12 internal current
sources for current balance. And the current
matching can achieve 2.5% regulation accuracy
between strings. Its low 600mV regulation
voltage on LED current sources reduces power
loss and improves efficiency.
PWM dimming is implemented with external
PWM input signal or DC input signal. The
dimming PWM signal can be generated internally,
and the dimming frequency is programmed by
an external setting capacitor.
MP3399 Rev. 1.0
3/27/2013
•
•
•
12 String, 60mA/String WLED Driver
Cascading Capability with a single Power
Source
5V to 28V Input Voltage Range
Maximum 60mA for Each String
2.5% Current Matching Accuracy Between
Strings
Programmable Switching Frequency
PWM or DC Input Burst PWM Dimming
Open and Short LED Protection
Programmable Over-voltage Protection
Under Voltage Lockout
Thermal Shutdown
28-pin TSSOP and 28-pin SOIC Package
APPLICATIONS
•
•
•
Desktop LCD Flat Panel Displays
Flat Panel Video Displays
LCD TVs and Monitors
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Quality Assurance. “MPS” and “The
Future of Analog IC Technology” are Registered Trademarks of Monolithic
Power Systems, Inc.
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1
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
TYPICAL APPLICATION
M1
D1
L1
VOUT
VIN
5V~28V
CIN
String1
String 12
String 13
String 24
COUT
VFAULT
CFAULT
RF1
2
VIN
VFAULT
27
RF2
VCC
3
CCOMP
CVCC
GATE
VCC
26
M2
COMP
4
Enable
5
8
ROSC
1
10
COMP
EN
6
DIMMING
RSET
9
11
12
13
14
2
CVCC
NC
PGND
OSC
NC
BOSC
RBOSC
7
ISENSE
OVP
MP3399
LED1
GND
LED2
DBRT
LED3
ISET
LED4
LED12
LED5
LED11
LED6
LED10
LED7
LED9
LED8
VIN
VFAULT
24
28
RSENSE
25
23
22
21
20
19
18
17
16
15
27
VCC
3
GATE
VCC
26
VOUT
COMP
4
COMP
ISENSE
24
RF3
5
EN
NC
28
RF4
8
ROSC
1
10
NC
BOSC
RBOSC
7
6
RSET
9
11
12
13
14
MP3399 Rev. 1.0
3/27/2013
PGND
OSC
OVP
MP3399
LED1
GND
LED2
DBRT
LED3
ISET
LED4
LED12
LED5
LED11
LED6
LED10
LED7
LED9
LED8
25
23
22
21
20
19
18
17
16
15
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2
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
ORDERING INFORMATION
Part Number
Package
Top Marking
Free Air Temperature (TA)
MP3399EF*
TSSOP28
3399EF
-20°C to +85°C
MP3399EY**
SOIC28
3399EY
-20°C to +85°C
*For Tape & Reel, add suffix –Z (eg. MP3399EF–Z).
For RoHS compliant packaging, add suffix –LF (eg. MP3399EF–LF–Z)
**For Tape & Reel, add suffix –Z (eg. MP3399EY–Z).
For RoHS compliant packaging, add suffix –LF (eg. MP3399EY–LF–Z)
PACKAGE REFERENCE
TOP VIEW
TSSOP28
NC
1
28
NC
VIN
2
27
VFAULT
VCC
3
26
GATE
COMP
4
25
PGND
ISENSE
EN
5
24
DBRT
6
23
OVP
GND
7
22
LED1
OSC
8
21
LED2
ISET
9
20
LED3
BOSC
10
19
LED4
LED12
11
18
LED5
LED11
12
17
LED6
LED10
13
16
LED7
LED9
14
15
LED8
SOIC28
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
VIN .................................................-0.3V to +30V
VGATE ..............................................-0.5V to 6.8V
VVCC ................................................-0.5V to 6.8V
VLED1 to VLED12 ..................................-1V to +50V
All Other Pins ...............................-0.3V to +6.3V
(2)
Continuous Power Dissipation (TA = +25°C)
TSSOP28…………………………………...3.9 W
SOIC28………………………………………2.1W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature............... -65°C to +150°C
TSSOP28 ................................32 ....... 6 .... °C/W
Recommended Operating Conditions
(3)
Supply Voltage VIN ..............................5V to 28V
LED Current (Backlight) .............10mA to 60mA
Maximum Junction Temp. (TJ) ................+125°C
MP3399 Rev. 1.0
3/27/2013
(4)
θJA
θJC
SOIC28 ..................................60 ...... 30 ... °C/W
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-toambient 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
operation conditions.
4) Measured on JESD51-7, 4-layer PCB.
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3
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
ELECTRICAL CHARACTERISTICS
VIN =12V, VEN = 5V, TA = +25°C, unless otherwise noted.
Parameters
Symbol
Condition
Min
Operating Input Voltage
VIN
Supply Current (Quiescent)
IQ
VIN=12V, VEN=5V, no load with
switching
Supply Current (Shutdown)
IST
VEN=0V, VIN=12V
LDO Output Voltage
VCC
Input UVLO Threshold
VIN_UVLO
4.5
VEN=5V,
0<IVCC<10mA
Rising Edge
7V<VIN<28V,
VEN_HIGH
VEN Rising
EN Low Voltage
VEN_LOW
VEN Falling
OSC Voltage
Maximum Duty Cycle
28
V
mA
2
μA
5.5
6
6.5
V
3.4
3.9
4.3
V
1.8
TON_MIN
V
4
Ω
VCC=6V,IGATE=10mA
2
Ω
6
V
ROSC= 115kΩ
510
570
630
kHz
ROSC= 374kΩ
150
170
190
kHz
1.18
1.23
1.28
V
PWM Mode,
when no pulse skipping happens
DMAX
ISENSE Limit
V
0.6
VGATE
fSW
mV
VCC=6V,VGATE=6V
VOSC
Minimum On Time
Units
200
EN High Voltage
Switching Frequency
Max
4
Input UVLO Hysteresis
STEP-UP CONVERTER
Gate Driver Impedance
(Sourcing)
Gate Driver Impedance
(Sinking)
GATE Voltage
Typ
100
ns
90
Max Duty Cycle
175
%
220
265
mV
COMP Source Current Limit
ICOMP SOLI
65
μA
COMP Sink Current Limit
ICOMP SILI
15
μA
PWM DIMMING
DBRT Leakage Current
IDBRT_LK
BOSC Frequency
FBOSC
BOSC Output Current
-5
CBOSC=2.2nF
5
μA
1.2
1.6
2
kHz
IBOSC
6.37
7.5
8.63
uA
VISET
1.20
1.22
1.245
V
29.6
30.5
31.4
mA
2.5
%
LED CURRENT REGULATION
ISET Voltage
LEDX Average Current
Current Matching
MP3399 Rev. 1.0
3/27/2013
(5)
ILED
RISET=40kΩ
ILED=30.5mA
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4
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
ELECTRICAL CHARACTERISTICS (continued)
VIN =12V, VEN = 5V, TA = +25°C, unless otherwise noted.
Parameters
Symbol
LEDX Regulation Voltage
Condition
VLEDX
ILED=30.5mA
OVP Over Voltage Threshold
VOVP_OV
Rising Edge
OVP UVLO threshold
VOVP_UV
Step-up Converter Fails
LEDX UVLO Threshold
Min
Typ
Max
600
Units
mV
PROTECTION
1.17
1.23
1.3
V
50
70
90
mV
VLEDX_UV
156
196
236
mV
LEDX Over Voltage Threshold
VLEDX_OV
5.8
6.3
6.8
V
Thermal Shutdown Threshold
TST
VFAULT Pull Down Current
VFAULT Blocking-Off Voltage
(with Respect to VIN)
IFAULT
VFAULT
150
VIN =12V, VIN-VFAULT
℃
40
55
70
μA
5.3
5.8
6.3
V
Notes:
5) Matching is defined as the difference of the maximum to minimum current divided by 2 times average currents.
MP3399 Rev. 1.0
3/27/2013
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5
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
PIN FUNCTIONS
Pin #
Name
Description
1
NC
No Connect.
2
VIN
Supply Input. VIN supplies the power to the chip, as well as the step-up converter switch.
Drive VIN with a 5V to 28V power source. Must be locally bypassed.
3
VCC
The Internal 6V Linear Regulator Output. VCC provides power supply for the internal
MOSFET switch gate driver and the internal control circuitry. Bypass VCC to GND with a
ceramic capacitor.
4
COMP
Step-up Converter Compensation Pin. This pin is used to compensate the regulation
control loop. Connect a ceramic capacitor from COMP to GND.
5
EN
6
DBRT
7
GND
Analog Ground.
8
OSC
Switching Frequency Set. Connect a resistor between OSC and GND to set the step-up
converter switching frequency. The voltage at this pin is regulated to 1.23V. The clock
frequency is proportional to the current sourced from this pin.
ISET
LED Current Set. Tie a current setting resistor from this pin to ground to program the
current in each LED string. The MP3399 regulates the voltage across the current setting
resistor. The regulation voltage is 1.22V. The proportion of the current through the ISET
resistor and the LED current is 1:1000.
10
BOSC
Dimming Repetition Set. This is the timing pin for the oscillator to set the dimming
frequency. To use DC input PWM dimming mode, connect a capacitor from this pin to
GND to set the internal dimming frequency. A saw-tooth waveform is generated on this
pin. To use external PWM dimming mode, connect a resistor from this pin to GND, and
apply the PWM signal on DBRT pin.
11
LED12
LED String 12 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 12 cathode to this pin.
12
LED11
LED String 11 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 11 cathode to this pin.
13
LED10
LED String 10 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 10 cathode to this pin.
14
LED9
LED String 9 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 9 cathode to this pin.
15
LED8
LED String 8 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 8 cathode to this pin.
9
MP3399 Rev. 1.0
3/27/2013
Enable Control Input. Do not let this pin float. It is recommended TO locally filter WITH a
0.1 μF ceramic capacitor.
Brightness Control Input. To use external PWM dimming mode, apply a PWM signal on
this pin for brightness control. To use DC input PWM dimming mode, apply a DC voltage
range from 0.2V to 1.2V on this pin linearly to set the internal dimming duty cycle from 0%
to 100%. The MP3399 has positive dimming polarity on DBRT.
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6
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
PIN FUNCTIONS (continued)
Pin #
Name
Description
16
LED7
LED String 7 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 7 cathode to this pin.
17
LED6
LED String 6 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 6 cathode to this pin.
18
LED5
LED String 5 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 5 cathode to this pin.
19
LED4
LED String 4 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 4 cathode to this pin.
20
LED3
LED String 3 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 3 cathode to this pin.
21
LED2
LED String 2 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 2 cathode to this pin.
22
LED1
LED String 1 Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED String 1 cathode to this pin.
23
OVP
Over-voltage Protection Input. Connect a resistor divider from output to this pin to
program the OVP threshold. When this pin voltage reaches 1.23V, the MP3399 triggers
OV Protection mode.
24
ISENSE
Current Sense Input. During normal operation, this pin senses the voltage across the
external inductor current sensing resistor for peak current mode control and also to limit
the inductor current during every switching cycle. If this pin is not used in extending
application with other master MP3399, tie this pin to GND, do not let this pin floating.
25
PGND
Step-up Converter Power Ground.
26
GATE
Step-up Converter Power Switch Gate Output. This pin drives the external power N-MOS
device.
27
VFAULT
Fault Disconnection Switch Gate Output. When the system starts up normally, this pin
smoothly turns on the external PMOS. When the MP3399 is disabled, the external
PMOS is turned off to disconnect the input and output. A ceramic cap is recommended to
add from this pin to GND to control the PMOS turn on speed so as to control the inrush
current at system start up.
28
NC
MP3399 Rev. 1.0
3/27/2013
No Connect.
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7
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN =12V, 12 LEDs in series, 24 strings parallel, 20mA/string, unless otherwise noted.
MP3399 Rev. 1.0
3/27/2013
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8
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
FUNCTION DIAGRAM
Figure 1—MP3399 Function Block Diagram
MP3399 Rev. 1.0
3/27/2013
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9
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
OPERATION
The MP3399 employs a programmable constant
frequency, peak current mode step-up converter
and 12-channels regulated current sources to
regulate the array of 12 strings white LEDs. The
operation of the MP3399 can be understood by
referring to the block diagram of Figure 1.
Internal 6V Regulator
The MP3399 includes an internal linear regulator
(VCC). When VIN is greater than 6.5V, this
regulator offers a 6V power supply for the internal
MOSFET switch gate driver and the internal
control circuitry. The VCC voltage drops to 0V
when the chip shuts down. In the application of
VIN smaller than 6.5V, tie VCC and VIN together.
The MP3399 features Under Voltage Lockout.
The chip is disabled until VCC exceeds the
UVLO threshold. And the hysteresis of UVLO is
approximately 200mV.
System Startup
When the MP3399 is enabled, the chip checks
the topology connection first. The VFAULT pin
drives the external Fault Disconnection PMOS to
turn on slowly. Then the chip monitors the OVP
pin to see if the Schottky diode is not connected
or the boost output is short to GND. If the OVP
voltage is lower than 70mV, the chip will be
disabled and the external PMOS is turned off
together. The MP3399 will also check other
safety limits, including UVLO and OTP after the
OVP test is passed. If they are all in function, it
then starts boosting the step-up converter with an
internal soft-start.
It is recommended on the start up sequence that
the enable signal comes after input voltage and
PWM dimming signal established.
Step-up Converter
The
converter
operation
frequency
is
programmable (from 150kHz to 500kHz) with a
external set resistor on OSC pin, which is helpful
for optimizing the external components sizes and
improving the efficiency.
At the beginning of each cycle, the external
MOSFET is turned with the internal clock. To
prevent sub-harmonic oscillations at duty cycles
MP3399 Rev. 1.0
3/27/2013
greater than 50 percent, a stabilizing ramp is
added to the output of the current sense amplifier
and the result is fed into the PWM comparator.
When this result voltage reaches the output
voltage of the error amplifier (VCOMP) the external
MOSFET is turned off.
The voltage at the output of the internal error
amplifier is an amplified signal of the difference
between the 600mV reference voltage and the
feedback voltage. The converter automatically
chooses the lowest active LEDX pin voltage for
providing enough bus voltage to power all the
LED arrays.
If the feedback voltage drops below the 600mV
reference, the output of the error amplifier
increases. It results in more current flowing
through the power FET, thus increasing the
power delivered to the output. In this way it forms
a close loop to make the output voltage in
regulation.
At light-load or Vout near to Vin operation, the
converter runs into the pulse-skipping mode, the
FET is turned on for a minimum on-time of
approximately 100ns, and then the converter
discharges the power to the output in the remain
period. The external MOSFET will keep off until
the output voltage needs to be boosted again.
Dimming Control
The MP3399 provides two PWM dimming
methods: external PWM signal or DC input PWM
Dimming mode (see Figure 2). Both methods
results in PWM chopping of the current in the
LEDs for all 12 channels to provide LED control.
DPWM
Comparator
Ex-PWM Input
DPWM Output
-
DBRT
+
DPWM
Oscillator
C BOSC
BOSC
Figure 2—PWM Dimming Method
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10
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
When bias the BOSC pin to a DC level by a
resistor, applying an external PWM signal to the
DBRT pin to achieve the PWM dimming. A DC
analog signal can be directly applied to the DBRT
pin to modulate the LED current. And the DC
signal is then converted to a DPWM dimming
signal at the setting oscillation frequency.
The brightness of the LED array is proportional to
the duty cycle of the DPWM signal. The DPWM
signal frequency is set by the cap at the BOSC
pin.
Open String Protection
The open string protection is achieved through
the over voltage protection. If one or more strings
are open, the respective LEDX pins are pulled to
ground and the IC keeps charging the output
voltage until it reach OVP threshold. Then the
part will mark off the open strings whose LEDX
pin voltage is less than 180mV. Once the markoff operation completes, the remaining LED
strings will force the output voltage back into tight
regulation. The string with the highest voltage
drop is the ruling string during output regulation.
MP3399 Rev. 1.0
3/27/2013
The MP3399 always tries to light at least one
string and if all strings in use are open, the
MP3399 shuts down the step-up converter. The
part will maintain mark-off information until the
part shuts down.
Short String Protection
The MP3399 monitors the LEDX pin voltage to
judge if the short string occurs. If one or more
strings are short, the respective LEDX pins will
be pulled up to the boost output and tolerate high
voltage stress. If the LEDX pin voltage is higher
than 6.5V, the short string condition is detected
on the respective string. When the short string
fault (LEDX over-voltage fault) continues for
greater than 2048 switching clocks, the string is
marked off and disabled. Once a string is marked
off, its current regulation is forced to disconnect
from the output voltage loop regulation. The
marked-off LED strings will be shut off totally until
the part restarts. If all strings in use are short, the
MP3399 will shut down the step-up converter.
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11
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
APPLICATION INFORMATION
Selecting the Switching Frequency
The switching frequency of the step-up converter
is programmable from 150kHz to 500kHz. A
oscillator resistor on OSC pin sets the internal
oscillator frequency for the step-up converter
according to the equation:
fSW = 67850 / ROSC（kΩ）
For ROSC=191kΩ, the switching frequency is set
to 355 kHz.
Setting the LED Current
The LED string currents are identical and set
through the current setting resistor on the ISET
pin.
ILED = 1000 x 1.22V / RSET
For RSET=60.4kΩ, the LED current is set to 20mA.
The ISET pin can not be open.
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
ceramic capacitor paralleled a 220uF electrolytic
capacitor is sufficient.
Selecting the Inductor and Current Sensing
Resistor
The inductor is required to force the higher output
voltage while being driven by the input voltage. A
larger value inductor results in less ripple current,
resulting in lower peak inductor current and
reducing stress on the internal N-Channel
MOSFET. However, the larger value inductor has
a larger physical size, higher series resistance,
and lower saturation current.
Choose an inductor that does not saturate under
the worst-case load conditions. A good rule for
determining the inductance is to allow the peakto-peak ripple current to be approximately 30% to
40% of the maximum input current. Calculate the
required inductance value by the equation:
V × (VOUT − VIN )
L = IN
VOUT × fSW × ΔI
MP3399 Rev. 1.0
3/27/2013
IIN(MAX) =
VOUT × ILOAD(MAX)
VIN × η
ΔI = (30%~40%) × IIN(MAX)
Where VIN is the minimum input voltage, fSW is the
switching frequency, ILOAD(MAX) is the maximum
load current, ∆I is the peak-to-peak inductor
ripple current and η is the efficiency.
The switch current is usually used for the peak
current mode control. In order to avoid hitting the
current limit, the voltage across the sensing
resistor RSENSE should be less than 80% of the
worst case current limit voltage, 220mV.
RSENSE =
0.8 × 0.22V
IL(PEAK )
Where IL(PEAK) is the peak value of the inductor
current.
Selecting the Power MOSFET
The MP3399 is capable of driving a wide variety
of N-Channel power MOSFETS. The critical
parameters of selection of a MOSFET are:
1. Maximum drain to source voltage, VDS(MAX)
2. Maximum current, ID(MAX)
3. On-resistance, RDS(ON)
4. Gate source charge QGS and gate drain
charge QGD
5. Total gate charge, QG
Ideally, the off-state voltage across the MOSFET
is equal to the output voltage. Considering the
voltage spike when it turns off, VDS(MAX) should be
greater than 1.5 times of the output voltage.
The maximum current through the power
MOSFET happens when the input voltage is
minimum and the output power is maximum. The
maximum RMS current through the MOSFET is
given by
IRMS(MAX) = IIN(MAX) × DMAX Where:
DMAX ≈
VOUT − VIN(MIN)
VOUT
The current rating of the MOSFET should be
greater than 1.5 times IRMS
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MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
The on resistance of the MOSFET determines
the conduction loss, which is given by:
Pcond = IRMS
2
× R DS (on) × k
Where k is the temperature coefficient of the
MOSFET.
The switching loss is related to QGD and QGS1
which determine the commutation time. QGS1 is
the charge between the threshold voltage and
the plateau voltage when a driver charges the
gate, which can be read in the chart of VGS vs. QG
of the MOSFET datasheet. QGD is the charge
during the plateau voltage. These two
parameters are needed to estimate the turn on
and turn off loss.
PSW =
Q GS1 × R G
× VDS × IIN × f SW +
VDR − VTH
Q GD × R G
× VDS × IIN × f SW
VDR − VPLT
Where VTH is the threshold voltage, VPLT is the
plateau voltage, RG is the gate resistance, VDS is
the drain-source voltage. Please note that the
switching loss is the most difficult part in the loss
estimation. The formula above provides a simple
physical expression. If more accurate estimation
is required, the expressions will be much more
complex.
Setting the Over Voltage Protection
The open string protection is achieved through
the over voltage protection (OVP). In some cases,
an LED string failure results in the feedback
voltage always zero. The part then keeps
boosting the output voltage higher and higher. If
the output voltage reaches the programmed OVP
threshold, the protection will be triggered.
To make sure the chip functions properly, the
OVP setting resistor divider must be set with a
proper value. The recommended OVP point is
about 1.2 times higher than the output voltage for
normal operation.
VOVP=1.23V*(R1+R2)/R2
Selecting Dimming Control Mode
The MP3399 provides 2 different dimming
methods
1. Direct PWM Dimming
An external PWM dimming signal is employed to
achieve PWM dimming control. Connect a 100kΩ
resistor from BOSC pin to GND and apply the
100Hz to 2kHz PWM dimming signal to DBRT
pin. The minimum recommended amplitude of
the PWM signal is 1.2V (See Figure 3).
For extended knowledge of the power loss
estimation, readers should refer to the book
“Power MOSFET Theory and Applications”
written by Duncan A. Grant and John Gowar.
The total gate charge, QG, is used to calculate
the gate drive loss. The expression is
PDR = Q G × VDR × f SW
Where VDR is the drive voltage.
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
4.7μF ceramic capacitor paralleled 10uF
electrolytic capacitor will be sufficient.
MP3399 Rev. 1.0
3/27/2013
Figure 3—Direct PWM Dimming
2. DC Input PWM Dimming
To apply DC input PWM dimming, apply an
analog signal (range from 0 V to 1.2V) to the
DBRT pin to modulate the LED current directly. If
the PWM is applied with a zero DC voltage, the
PWM duty cycle will be 0%. If the DBRT pin is
applied with a DC voltage>1.2V, the output will
be 100% (See Figure 4). The capacitor on BOSC
pin set the frequency of internal triangle
waveform according to the equation,:
FUNITE = 3.5uF / CUNITE
The dimming frequency is recommended set
from 100Hz to 2kHz.
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13
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
Layout Considerations
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 external MOSFET (M2),
output diode (D1), and output capacitor (C5) is
flowing with high frequency pulse current. It must
be as small as possible (See Figure 5).
Figure 4—DC input PWM Dimming
Extending LED Channels applications
The MP3399 is flexible for extending LED
channels with two or more MP3399s in parallel.
For the connection of two MP3399s extending 24
strings LEDs, please see the typical application
diagram in page 2. Tie the VCC pins of the
master IC and the slave IC together to provide
the power of the slave IC internal logic circuitry.
Also tie the COMP pins of the slave IC and the
master IC together to regulate the voltage of all
24 strings LEDs. The MOS driving signals of the
slave IC are not used, the boost converter can be
only driven by the master IC. Do not let the
Isense pin of the slave IC floating, tie it to GND.
The EN and Dimming signals should be applied
to both ICs. It is recommended to use external
PWM dimming mode to achieve the accurate
dimming synchronization of both parts.
Figure 5—Layout Consideration
The IC exposed pad is internally connected to
GND pin, and all logic signals are refer to the
GND. The PGND should be externally connected
to GND and is recommended to keep away from
the logic signals.
External MOSFET for Short Protection
When output voltage is higher than rating of
LED1-12 pins, external MOSFET is needed for
each LED channel to avoid destroying LED1 -12
pins. (See Figure 8 for 4 channels application)
The rating of MOSFET must be higher than 1.2*
VOUT t and more than 1.2* ILED.
MP3399 Rev. 1.0
3/27/2013
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14
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
TYPICAL APPLICATION CIRCUIT
8V-28V
VIN
L1
M1
C3
F1
D1
AM4499P
C13
B180
C16
LED+
C1
C2
C10
NC
R26
NC
C17
NC
5.6nF
R20
R11
GND
GND
C12
10
0
LED1
R51
LED2
C15
499k
GND
NC
GND
GND
LED5
GND
2
VIN
LED6
GND
U1
R54
VFAULT
27
10k
LED7
R22
LED8
0
3
VCC
GATE
R53
26
10k
C9
4
R1
C4
2k
EN
GND
R4
220nF
ISENSE
0
5
8
EN
NC
OSC
PGND
C14
100pF
28
LED9
LED10
LED11
24
R15
C18
20k
COMP
LED3
LED4
M2 AM4490N
R24
R25
0.05
NC
GND
LED12
25
R13
GND
340k
1
NC
OVP
23
R27 0
GND
GND
R8
C6
100k
NC
10
7
R2
DIMMING
14S 12P 20mA
BOSC
LED1
22
R28 0
MP3399
GND
LED2
DBRT
LED3
ISET
LED4
LED12
LED5
LED11
LED6
LED10
LED7
LED9
LED8
21
R29 0
2k
GND
NET00016
6
R16
R5
20k
20
R30 0
9
19
60.4k
R31 0
GND
11
18
R32 0
GND
12
17
R33 0
13
16
R34 0
14
15
R35 0
R36 0
R37 0
R38 0
Figure 6—Drive 14 LEDs in Series, 12 Strings 20mA/string
MP3399 Rev. 1.0
3/27/2013
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15
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
8V-28V
F1
VIN
C1
C2
L1
M1
C3
C17
C10
R26
NC
NC
GND
2
C9
NC
GND
VIN
VFAULT
VCC
GND
GATE
LED7
R23
10k
COMP
ISENSE
24
5
EN
NC
8
OSC
PGND
R24
28
C6
NC
OVP
LED12
NC
23
10
BOSC
LED1
22
MP3399
7
R28 0
GND
LED2
DBRT
LED3
21
R2
R29 0
GND
6
20
R16
R5
R30 0
9
20k
GND
R27 0
GND
NC
LED10
LED11
R25
GND
1
GND
R8
LED9
100pF
25
R13
100k
LED8
C14
GND
0
220nF
340k
2k
LED6
R53
R15
C4
C18
R4
LED5
1k
0
26
LED3
LED4
R52
R22
27
0.05
20k
GND
NC
4
LED2
C15
M2 AM4490N
COMP
2k
LED1
VCC
3
R1
R51
C12
VFAULT
10
U1
R54
DIMMING
12S 12/24 P 20mA
357k
OVP1
R20
GND
10k
EN
C16
VCC
5.6nF
0
GND
GND
C13
B180
LED+
R11
GND
D1
AM4499P
VIN
NC
ISET
LED4
LED12
LED5
LED11
LED6
19
60.4k
GND
R31 0
11
18
R32 0
GND
12
17
R33 0
13
LED10
LED7
LED9
LED8
16
R34 0
14
15
R35 0
R36 0
R37 0
R38 0
VCC
VIN
VFAULT
R19
R12
2
R21
U2
NC
0
VIN
NC
VFAULT
27
LED13
3
COMP
C7
NC
GND
R7
VCC
GATE
26
LED14
R17
NC
LED15
4
COMP
ISENSE
24
LED16
LED17
0
5
8
EN
NC
OSC
PGND
28
R14
1
GND
10
NC
BOSC
LED1
22
NC
7
GND
GND
LED21
R39 0
R40 0
LED2
LED22
LED23
LED24
21
R41 0
GND
6
DBRT
LED3
ISET
LED4
20
R18
R42 0
9
GND
LED20
100pF
23
MP3399
C8
100k
OVP
LED19
C11
GND
340k
R9
LED18
OVP1
25
19
60.4k
R43 0
11
LED12
LED5
LED11
LED6
LED10
LED7
18
R44 0
12
17
R45 0
13
16
R46 0
14
LED9
LED8
15
R47 0
R48 0
R49 0
R50 0
Figure 7—Drive 12 LEDs in Series, 24 Strings 20mA/string
MP3399 Rev. 1.0
3/27/2013
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MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
8V-28V
VIN
L1
M1
C3
F1
D1
AM4499P
C13
B180
18S 4P 60mA
C16
LED+
C1
C2
C10
NC
NC
C17
R26
NC
5.6nF
R20
R11
GND
10
0
GND
C12
R51
C15
499k
GND
NC
GND
M2 AM4490N
GND
GND
U1
R54
2
VIN
VFAULT
27
10k
R22
0
3
VCC
GATE
4
R1
C4
10k
GND
0
5
C18
8
20k
COMP
ISENSE
24
R15
EN
NC
OSC
PGND
28
R25
0.05
NC
GND
LED1
25
LED2
R13
GND
340k
1
NC
OVP
LED3
23
LED4
R27 0
GND
R8
10
BOSC
C6
100k
NC
7
R2
LED1
22
M3
R28 0
MP3399
GND
LED2
DBRT
LED3
ISET
LED4
LED12
LED5
LED11
LED6
LED10
LED7
4
GND
21
NET00016
6
R16
R5
20k
20
R30 0
9
19
60.4k
M4
R31 0
GND
11
4
GND
3
R29 0
2k
18
R32 0
GND
12
17
R33 0
13
3
DIMMING
R24
1,2,5,6
R4
220nF
100pF
M3-M6: AM3490N
LED9
LED8
100V/1A
TSOP6
16
M5
4
R34 0
14
1,2,5,6
2k
EN
C14
R53
26
C9
15
3
R35 0
1,2,5,6
GND
M6
4
R37 0
3
R38 0
1,2,5,6
R36 0
VIN
R39
0
R40
NC
GND
Figure 8 – Drive 18LEDs in Series, 4 strings 60mA/string
Note: For Vin>15V application, use R139 and R40(10kΩ) divider to make a 15V bias voltage for M3-M6.
MP3399 Rev. 1.0
3/27/2013
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17
MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
PACKAGE INFORMATION
PACKAGE OUTLINE DRAWING FOR 28-TSSOP w/ EXPOSED PADDLE
5.90
TYP
9.60
9.80
0.65
BSC
0.40
TYP
28
15
1.60
TYP
4.30
4.50
PIN 1 ID
3.20
TYP
6.20
6.60
5.80
TYP
14
1
TOP VIEW
RECOMMENDED LAND PATTERN
0.80
1.05
1.20 MAX
SEATING PLANE
0.19
0.30
0.65 BSC
0.00
0.15
0.09
0.20
SEE DETAIL "A"
FRONT VIEW
SIDE VIEW
GAUGE PLANE
0.25 BSC
5.70
6.10
0o-8o
0.45
0.75
DETAIL “A”
2.60
3.10
BOTTOM VIEW
MP3399 Rev. 1.0
3/27/2013
NOTE:
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,
PROTRUSION OR GATE BURR.
3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH
OR PROTRUSION.
4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING)
SHALL BE 0.10 MILLIMETERS MAX.
5) DRAWING CONFORMS TO JEDEC MO-153, VARIATION AET.
6) DRAWING IS NOT TO SCALE.
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MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER
PACKAGE INFORMATION
SOIC28
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.
MP3399 Rev. 1.0
3/27/2013
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19