MLX10803 DataSheet old 249 DownloadLink 4840

MLX10803
IC specification
High power LED driver
Features
General
•
•
•
•
•
•
•
•
Low cost power LED driver for external n-channel MOSFET
switching transistor
6V to 32V DC input range
Applications from mA to several Ampere LED current
Possible temperature dependent regulation using external
Negative Temperature Coefficient (NTC) resistor
Small package allows compact module design with minimised
wire runs and short connections to achieve improved EMC
performance
Built-in randomiser for improved EMC performance
High temperature operation capable
Load dump protected to 80V
VREF
1
8
ROSC
2
7 DRVGATE
IREF1
3
IREF2
4
10803
(SOIC8)
6
VS/PWM
GND
5 RSENSE
LED driver
•
•
•
•
High energy efficiency
PWM dimming via VS/PWM pin
Light output has minimised dependency on supply and
temperature variations
LED regulation parameters set with external resistors
Ordering Information
Part Nr
Temperature Code
MLX10803
K (-40°C to 125°C)
Package Code
DC (SOIC8)
General Description
The MLX10803 is a multi-purpose LED driver for high power LEDs designed for high current and high voltage
applications. The circuit is designed for demanding automotive applications and therefore suitable in all other high
intensity LED applications.
Numerous adjustment possibilities allow for the design of different LED applications using only a few external
components.
The circuit is load dump protected for 80V load dump pulse.
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Data Sheet
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IC specification
High power LED driver
Table of contents
Features .....................................................................................................1
Ordering Information...................................................................................1
General Description....................................................................................1
Table of contents ........................................................................................2
Block diagram.............................................................................................3
1.
Typical application data .....................................................................4
1.1.
LED driver applications...............................................................4
1.1.1. Principle complete schematic LED driver diagram..................4
1.1.2. Principle minimum schematic LED driver diagram..................4
1.1.3. Principle soft start up LED driver diagram...............................5
1.1.4. LED driver application notes ...................................................5
2.
Application pins .................................................................................7
3.
Absolute maximum ratings ................................................................7
4.
Electrical characteristics ....................................................................8
5.
ESD/EMI recommendations for MLX10803.....................................11
6.
Automotive test pulses ....................................................................12
6.1.
Test pulse definition .................................................................13
7.
LED driving principle........................................................................16
7.1.
General.....................................................................................16
7.2.
The principle in detail................................................................17
7.3.
Switching frequency considerations and constant light output .20
8.
Temperature regulation ...................................................................21
9.
Mechanical Data ..............................................................................22
9.1.
Mechanical data of the MLX10803 package ............................22
10. Standard information regarding manufacturability of Melexis
products with different soldering processes.....................................23
11. History record ..................................................................................24
12. Disclaimer........................................................................................25
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MLX10803
IC specification
High power LED driver
Block diagram
VS/PWM
Regulator VDD
VDD
5.0 V ± 10 %
Power on Reset
POR
Trim Logic
(incl. Zener Zaps)
RSENSE
Debouncing
300 ns
Reference Currents
COMP
...
Iref_x
COMP
4V
RC Oscillator
ROSC
tunable: 0.5 MHz to 5 MHz
frequ. tolerance: ± 20 %
IREF2
4V
1.25V
divider
1/5
Start OFF
Start ON
divider
1/10
Minimal
voltage
selection
IREF1
VREF
Monoflop with
pseudo random
generator
OFF Timer
4.2 µs (average value)
at fOSC = 2.5 MHz
ON Timer
23.4 µs (average value)
at fOSC = 2.5MHz
GND
COMP
VS/PWM
20mV
Clamping
max. 12 V
OFF
FF
DRVGATE
ON
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Data Sheet
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MLX10803
IC specification
High power LED driver
1.
Typical application data
1.1.
LED driver applications
1.1.1. Principle complete schematic LED driver diagram
Cap for EMC directly
on the connector
100nF...1uF
VBAT
100nF
VS/PWM
VREF_SET
VREF
VS/PWM
ROSC
DRVGATE
IREF1
GND
IREF2
RSENSE
Cnoise
NTC
GND
Figure 1:
Application with PWM dimming via VS/PWM pin. Amplitude of LED’s current is set
by an analogue voltage on input VREF_SET. Temperature regulation of LED’s current is realized by
external resistors on pins IREF1 and IREF2
1.1.2. Principle minimum schematic LED driver diagram
Vsup
VREF
VS/PWM
ROSC
DRVGATE
IREF1
GND
IREF2
RSENSE
GND
Figure 2:
3901010803
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Minimum application without temperature and external EMC protection
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Data Sheet
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MLX10803
IC specification
High power LED driver
1.1.3. Principle soft start up LED driver diagram
Cap for EMC directly
on the connector
100nF...1uF
VBAT
100nF
VREF
ROSC
VS/PWM
DRVGATE
IREF1
GND
IREF2
RSENSE
GND
Figure 3:
Application with gradual increase of light intensity after power up (soft start)
1.1.4. LED driver application notes
The MLX10803 is optimised for the use of low cost coils and n-channel MOSFETs. For a standard application with
1 LED and an average current of 350mA, a coil of about 100µH…220µH and ≤ 1Ω DC resistance should be
chosen. The sense resistor should have a value between 0.27Ω…0.47Ω / 250mW.
As a general rule: for higher load current lower inductance of the coil is needed because higher currents lengthen
the charging time of the coil. Thus, switching frequencies may become lower than 20kHz which is often not desired.
It is possible to set the peak current and the average current of the LED by variation of the RSENSE resistor, the
coil value and the internal oscillator frequency (ROCS resistor).
The flyback diode that carries the load current during the passive state (driver OFF) should be a fast switching and
low intrinsic capacitance diode like ES1D or BYG80 in order to avoid parasitic spikes on RSENSE. The diode must
be able to carry the LED current flowing during the OFF time of the driver.
The n-channel MOSFET should have low intrinsic capacitances, a drain-source voltage suitable for the application
and must be able to carry the current flowing through the LED(s) during the ON time. To decrease the time of
transistor switching and to improve the thermal behaviour of the module, the lines between transistor and IC should
be minimised.
For applications that use an NTC resistor for temperature sensing, the NTC value has to be selected according to
the application requirements. For most applications, a NTC value up to 470kΩ will be suitable.
In case of longer lines between the IC and the coil (which should be avoided because of EMI), a capacitor might be
placed in parallel to RSENSE to avoid crosstalk and parasitic switching. Well chosen parameters for external
components can help to avoid such conditions. The goal should be to unload the coil as much as possible during
the selected off time (see also chapter 7).
To reduce an influence of noise which can be coupled to sensitive reference pins IREF1, IREF2 it is possible to
connect noise-filtering capacitors in parallel to IREF1 and IREF2 resistors (see Figure 1, Cnoise capacitors). The
coupling also should be reduced as much as possible by proper routing of IREF1 and IREF2 stripes on PCB. IREF2
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Data Sheet
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MLX10803
IC specification
High power LED driver
resistor should be placed as close as possible to IREF2 pin and stripe from IREF1 pin to NTC resistor should be
shielded by GND stripe.
The schematic diagram under Figure 1 is used in applications where the LED is controlled by external control
electronics. A PWM with a frequency between 30Hz..5kHz can be applied to the VS/PWM pin in order to
dim the light output. This frequency is limited by the time needed for recharging the coil and monoflop time selected
by the resistor connected to ROSC as well as by the IC settling time after POR. This function can be used to
achieve different light outputs or also be used in a temperature down regulation.
It is recommended to have the PWM frequency at least 5-10 times lower than the selected driver switching
frequency.
Diode is placed between DRVGATE and VS/PWM IC pins serves as discharger of gate of FET transistor. Thus,
having switched off IC at VS/PWM voltage=0 DRVGATE turns to Z-state. Charge that was stored in gate capacitor
runs down to VS/PWM module pin via the diode.
The minimum schematic diagram under Figure 2 is sufficient for all applications with a constant light output.
We also recommend to compare with our other circuits in the MLX108xx family and study these application notes
for suitable solutions.
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MLX10803
IC specification
High power LED driver
2.
Nr.
1
2
3
4
5
6
7
8
3.
Application pins
Name
VREF
ROSC
IREF1
IREF2
RSENSE
GND
DRVGATE
VS/PWM
Function
Analogue input, setting of LED peak current
External resistor sets internal Oscillator frequency. Sets the average discharge time of the coil
External NTC resistor for temperature down regulation
External resistor sets the temperature breakpoint when the NTC resistor starts down regulation
External sense resistor pin for peak current detection
Ground
Pin driving the gate of the switching transistor
Supply Voltage / PWM signal
Absolute maximum ratings
Parameter
Power supply (VS/PWM)
Symbol
vs
Condition
DC
Min
-0.3
Max
32
Unit
V
Power supply, non operational function (off)
max. 0.5s (Load dump)
Input current in protection circuitry on any pin
vsmax
max 0.5s
32
80
V
iprot
10
mA
Input voltage on RSENSE pin
virsense
Input voltage on IREF1, IREF2, VREF pins
vrefmax
In case of
-10
maximum
supply ratings
normal
-0.3
operation
without external -0.3
resistor
Input voltage on ROSC pin
vroscmax
Input voltage on DRVGATE pin
vdrvgatmax
Input/output current on DRVGATE pin
Junction temperature
Lifetime
Dynamic
Storage temperature
Ambient temperature range
idrgatemax
Tjunc
Thermal resistance junction to ambient
rth
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Tambient
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protected by
external 47k
resistor
normal
operation
idrvgatemax
current must
not be
exceeded
pulse mode
normal
operation.
max. 100h
normal
operation
SOIC8
11
40
V
-80
(0.5s)
-0.3
80
(0.5s)
Vdd+0.3
V
V
-0.3
22
V
500
mA
°C
-40
-40
-55
-40
140
150
150
125
°C
128.4
K/W
Data Sheet
17/AUG/06
MLX10803
IC specification
High power LED driver
4.
Electrical characteristics
Following characteristics are valid
- for the full temperature range of Tambient = -40°C to +125°C,
- a supply range of 32V ≥ vs > 6V
unless other conditions noted.
With 6V ≥ vs > vporh analogue parameters can not be guaranteed.
Note: The correct operation of the MLX10803 as a switching mode power supply for voltages lower than the
nominal supply voltage is dependent on the forward bias voltage of the used LED.
The user must ensure that at low supply voltage the peak current threshold voltage on the RSENSE pin can
be reached in order to keep the switching principle working.
If several pins are charged with transients above VS/PWM and below GND, the sum of all substrate currents of the
influenced pins should not exceed 10mA for correct operation of the device.
Normal operating supply voltage is supposed to be 13.8V.
Parameter
Symbol
Conditions
Min
Maximum current during
80V load dump
Normal supply current at
highest DC voltage
Normal supply current
Limits
Typ
Units
Max
ihv
Global parameters
vs=80V
10
mA
inomdch
vs=32V
2
mA
inom
vs=13.8V
700
µA
10
µs
IC settling time
IC settling time after
power on reset
tsettle
Oscillator related parameters
The min/max specification influences inversely all derived timings
Min oscillator frequency
foscmin
For a selected
0.4
0.5
0.6
external resistor of
440kΩ and room
temperature
Max oscillator frequency
foscmax
For a selected
4.0
5.0
6.0
external resistor of
40kΩ and room
temperature
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MHz
MHz
Data Sheet
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MLX10803
IC specification
High power LED driver
Power on reset level, if
VS/PWM is ramped up
Internal supply voltage
range
RESET related parameters
(Reset is
2
connected to the
internal Vdd, but
vporh is measured
on pin VS/PWM)
Vdd related parameters (Vdd used internally only)
vdd
vs=13.8V
4.5
vporh*
Input leakage current
ileakrsense
Debounce time after
switching on
Threshold voltage on
RSENSE
tdeb
Leakage current
DRVGATE cessation
voltage
Sensitive voltage range
Linear voltage range
ileakvref
vswoff
Output current for
external reference
measurement
Temperature drift of the
current
vrsensethr
vvrefrng
vvreflinrng
iiref1
viref1rng
viref1linrng
Difference of iiref2 to
iiref1
Temperature drift of the
current
difiref12
Sensitive voltage range
Linear voltage range
viref2rng
viref2linrng
Max output voltage in ON
state
Output resistance of
push-pull output
vmaxdrv
vs=13.8V
vswoff
vs=13.8V
0.1
IREF1 related parameters
vs=13.8V,
47.5
viref1=viref1rng
5.5
V
20
µA
400
ns
3.8
3.8
V
V
52.5
µA
-0.1
vs=13.8V
vswoff
vs=13.8V
0.1
IREF2 related parameters
vs=13.8V,
-10
viref1=viref2rng
iiref2drift
Rdrvgateout
V
Minimum value of voltage on pins IREF2,
IREF1 and VREF divided by 5 or by 10 (see
7.2)
VREF related parameters
-0.3V<vvref<5V
-20
20
µA
vs=13.8V
15
20
25
mV
iiref1drift
Sensitive voltage range
Linear voltage range
3901010803
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RSENSE related parameters
vs=13.8,
-20
-0.3V<vrsense<5V
200
4
%/°C
3.8
3.8
V
V
+10
%
-0.1
vs=13.8V
vswoff
vs=13.8V
0.1
DRVGATE related parameters
Load current 1µA 10.0
to GND, vs=13.8V
To GND pin
6
12
To VS/PWM pin,
100
200
vs=13.8V
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%/°C
3.8
3.8
V
V
14.0
V
18
300
Ω
Ω
Data Sheet
17/AUG/06
MLX10803
IC specification
High power LED driver
Output voltage
Resistance on pin to GND
*
for 0.5MHz
Resistance on pin to GND
*
for 1MHz
Resistance on pin to GND
*
for 5MHz
vrosc
Roscmin
ROSC related parameters**
vs=13.8V
1
440
V
kΩ
Roscmid
220
kΩ
Roscmax
40
kΩ
9
µs
16
µs
60.5
µs
Monoflop related parameters**
Minimum OFF time due to toffmin1mhz
Oscillator is set to
the implemented jitter
1 MHz, in case the
oscillator is put to
an other
frequency,
toffmin1mhz
scales accordingly
Maximum OFF time due
toffmax1mhz
Oscillator is set to
to the implemented jitter
1 MHz, in case the
osc is put to an
other frequency,
toffmax1mhz
scales accordingly
Average monoflop time
ton1mhz
Oscillator is set to
for ON state of transistor
1 MHz
1.5
* vporh can be lower than minimum specified value at 125C ambient temperature. This doesn’t affect the
functionality of IC
** Value for the resistor Rosc to be connected to ROSC pin is derived from the needed monoflop time Tmon
according to the following expression:
3901010803
Rev 022
Rosc[kΩ] = 222.2 ⋅ (
Tmon[ µs ]
− 0.02)
12.5
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Data Sheet
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MLX10803
IC specification
High power LED driver
5.
•
•
•
•
ESD/EMI recommendations for MLX10803
In order to minimise EMI, the PCB has to be designed according to EMI guidelines. Additional components may
be needed, other than what is shown in the application diagrams, in order to comply with
the EMI requirements.
The MLX10803 is an ESD sensitive device and has to be handled according to EN100015 part 1.
The MLX10803 will fulfil the requirements in the application according to the specification and to DIN 40839 part
1.
The MLX10803 is designed with ESD protection >1000V HBM according to MIL883D.
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Data Sheet
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MLX10803
IC specification
High power LED driver
6.
Automotive test pulses
The following chapter is valid for a completely assembled module. That means that automotive test pulses are
applied to the module and not to the single IC.
In the recommended application according to chapter 1.1, the reverse polarity diode together with the capacitors
on the supply and the load dump protected IC itself protect the module against the automotive test pulses listed
below.
The exact values of the capacitors for the application have to be figured out according to the automotive and
EMI requirements.
No damage occurs for any of the test pulses. A deviation of the IC’s characteristics is allowed during pulse 1, 2, 4;
the module returns to normal operation after the pulse without any additional action.
During test pulse 3a, 3b, 5 the module operates within characteristic limits.
Parameter
Symbol
Min
Max
Dim
Test condition,
Functional status
Transient test pulses in accordance to ISO7637 part 1 & 3. Pin VREF goes outside of module via
resistor of 47kΩ
Ω. Module schematic is according to application notes mentioned in 1.1.1.
Test pulse #1 at module pins VBAT,
vpulse1
-100
V
5000 pulses,
VS/PWM. VREF_SET, IC pin IREF1 ->
functional state C
GND
Test pulse #2 at module pins VBAT,
vpulse2
100
V
5000 pulses
VS/PWM. VREF_SET, IC pin IREF1 ->
functional state C
GND
Test pulse #3a at module pins VBAT,
vpulse3a
-150
V
1h,
VS/PWM. VREF_SET, IC pin IREF1 ->
functional state A
GND
Test pulse #3b at module pins VBAT,
vpulse3b
100
V
1h,
VS/PWM. VREF_SET, IC pin IREF1 ->
functional state A
GND
Test pulse #4 at module pin VBAT,
vspulse4
-6
-4
V
1 pulse,
VS/PWM, VREF_SET -> GND
vapulse4
-5
-2.5
V
functional state C
Test pulse #5 at IC pin VS/PWM -> GND
vpulse5
45
85
V
functional state C
Description of functional status:
A:
All functions of the module are performed as designed during and after the disturbance.
B:
All functions of the module are performed as designed during and after the disturbance:
However, one or more can deviate from specified tolerance. All functions return automatically
to normal limits after exposure is removed. Memory functions shall remain class A.
C:
A function of the module is not performed as designed during disturbance but returns automatically to
a normal operation after the disturbance.
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IC specification
High power LED driver
6.1.
Test pulse definition
Test Pulse 1
Ri = 10 Ω
200ms
V
<100µs
12V
t
10%
vpulse1
90%
1µs
2ms
0.5s…5s
Test Pulse 2
Ri=10 Ω
0.5…5s
V
50µs
1µs
90%
vpulse2
10%
12V
200ms
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t
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IC specification
High power LED driver
Test Pulse 3a
Ri = 50 Ω
V
10ms
90ms
12V
t
vpulse3a
100µs
100ns
5ns
10%
90%
Test Pulse 3b
Ri = 50 Ω
V
100µs
vpulse3b
12V
10ms
t
90ms
90%
10%
5ns
100ns
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IC specification
High power LED driver
Test Pulse 4 (Cranking)
Ri = 0.01Ω
V
12V
vapulse4
vspulse4
5ms
15ms 50
ms
0.5-20s
100 ms
t
Test Pulse 5 (Load Dump)
Ri = 0.5…4Ω
V
Pulse 5
90%
vpulse5
80V
10%
12V
t
tr = 0.1...10ms
td = 40...400ms
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Data Sheet
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IC specification
High power LED driver
7.
LED driving principle
7.1.
General
The LED is driven by a switched mode power supply using an inductor as the energy storage element. This method
has several advantages. The supply voltage has to be set down to the forward bias voltage of the LED. In ordinary
applications this is achieved by a resistor with the following drawbacks:
- A resistor dissipates power which is transformed to heat
- Efficiency is reduced drastically
- The light output of the LED is dependent on the supply and the temperature of the resistor
The MLX10803 avoids these disadvantages as shown by the following calculation with L=220µH, RSENSE = 0.1 Ω:
Supposed:
Vbat = 13.8V
VfLED ≈ 3.4V example 1; 8V example2;
IfLED ≈ 4A
Vf1 ≈ 0.9V (reverse polarity diode)
Vf2 ≈ 0.9V (free wheel diode)
VRSENSE ≈ 0.4V (@IfLED, RSENSE=0.1 Ω)
VRDS ON ≈ 0.04V (@IfLED)
VCoil ≈ 0.2V (@IfLED)
Efficiency using a simple resistor or load dump regulation:
n=
Efficiency n:
V fLED
VBAT
≈ 29% example1; ≈ 58% example2;
Efficiency using the MLX10803:
The following calculation is an approximation only, due to the fact that coil current is not constant. It is therefore
calculated with average currents.
1) During OFF time, the coil acts as the storage element and delivers its energy to the flyback diode
and the LED:
n1 =
V fLED
V fLED + V f 2 + VCoil
≈ 75% example1; ≈ 88% example 2;
2) During ON time, current flows through the reverse polarity diode, LED, coil , FET driver and RSENSE,
which causes the following voltage drops:
n2 =
V fLED
V fLED + V f 1 + VCoil + V RDSon + V RSENSE
≈ 69% example1; ≈ 84% example 2;
3) ON and OFF times are in ratio of roughly 30:70 for example 1 and 65:35 for example 2:
Efficiency n: n = n1 ⋅ 0.7 + n2 ⋅ 0.3 ≈ 73% example1; ≈ 87% example2;
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IC specification
High power LED driver
7.2.
The principle in detail
After powering on the MLX10803 the switch becomes open and the current through the LED starts to rise. The rate
of current raise is limited by the value of the coil. When the current through the LED reaches half of a maximum
value, the ON timer is started, and if during 58.5 clocks of the internal oscillator the maximum current value through
the LED is not reached, the driver switches off. This maximum current is adjusted by the resistors on the IREF2,
IREF1 or voltage applied to VREF pins (voltage on these pins is divided by 5). The minimum of these voltages is
taken as a reference. The driver is switched off for a monoflop time, which is equal to 9…16 pulses of oscillator.
The frequency of the oscillator can be set by the customer using the Rosc value using such formula:
Fosc[ MHz ] = 222.2 /( Rosc[kΩ] + 4.44) .
Both parameters, the peak current threshold voltage and the monoflop time, create an ON/OFF period to form an
average current through the LED. By adjusting these parameters, an adjustment of the average load current is
possible in a wide range.
I
Imax2
Iavg2
Imax1
Iavg1
t
I
Imax
Iavg1
Iavg2
T1
t
T2
Note: The current sense comparator has a typical debouncing time of 300ns as shown in the block diagram. This
delay time prevents the driver from being switched off due to short term switching oscillations. When working with
very short monoflop times, this time has to be taken into account for calculations.
I
Imax
Iavg
tmon_off
t
By applying a PWM signal on VS/PWM, the LED can be dimmed from 0% to 100%.
VS/PWM = L
VS/PWM = PWM
VS/PWM = H
3901010803
Rev 022
LED permanent OFF
LED dimmed with PWM between 0% to 100%
LED permanent ON
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Data Sheet
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MLX10803
IC specification
High power LED driver
Dimming is achieved by applying a PWM directly to the module supply or by changing the reference voltage on pin
VREF or the resistor’s value on IREF2 pin.
IC settling times must always be considered in PWM mode. Please refer also to chapter 1.1.4 for
additional PWM frequency considerations.
Limitation of the ON time prevents from exceeding the allowed average current when the power supply voltage is
not sufficient for the current to reach its peak value and restricts in this case duty cycle of switching to 68%.
I
Imax
Iavg
Imax/2
tmon_on
tmon_off
t
A pseudo random generator is applied to the monoflop time. The pseudo random generator runs with the clock
derived out of the monoflop time and adds a random distribution on these 3 LSBs. Therefore, the monoflop time
gets a random variation from its value. The EMI behaviour of the complete module is improved due to the variation
of the otherwise fixed switching frequency.
The inductance L of a coil describes the amount of magnetic energy that can be stored in it.
Consequently, high inductive coils will be discharged less than low inductive coils in a given time.
Generally the coil can be driven in two different ways:
1)
The coil is discharged partially only. That means the coil still carries a significant amount of energy
when going from discharging to charging. In that moment the charging current rises immediately to
the coil current that was flowing just before switching. This is connected with large dI/dt transients on the
RSENSE pin that have a negative impact on EMI. This is mostly preferred way of regulation because of low
influence of supply voltage and coil value on output current. Fast flyback diode is recommended and extra
important in this case.
2)
The coil discharged completely. Thus, at the end of a discharging cycle, the coil doesn’t carry energy
anymore. With the next charging cycle, current increases steadily from around zero. This way, large dI/dt
transients are completely avoided.
3901010803
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Data Sheet
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MLX10803
IC specification
High power LED driver
Because of randomisation, the discharging time is not constant but varies within a certain range. It must be
ensured that only the longest possible monoflop time completely discharges the coil. Otherwise the coil is
discharged before the monoflop time ends which results in a loss of accuracy.
I
Resistance 2
Imax2
Imax1
Iavg
Resistance 1
Coil 1
Coil 2
Toff
Coil 1 > Coil 2
Resistance 1 > Resistance 2
t
Conclusion:
In most cases the coil is driven in a combination of both ways. A trade off has to be made between
EMI behaviour and maximum allowed LED current. By varying these parameters, an optimum can
be found for every application.
Below are some examples for typical parameter sets given for a 4A LED current and the following application data:
•
•
•
•
RSENSE = 0.1 Ω/ 2 watt
ROSC = 270kΩ
L = 47µH, 4A minimum, 0.05 Ω
Normal nFET switch transistor, rds on < 0,01 Ω
Remarks:
• 4A and 0.05 Ω results in 0.8 watt power dissipation over the coil.
• 4A and 0.1 Ω for the RSENSE resistor results in 1.6 watt, but only for 50% of the time in average.
• The LED(s) with this current will dissipate 32 watt if they have 8V forward voltage.
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Data Sheet
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MLX10803
IC specification
High power LED driver
7.3.
Switching frequency considerations and constant light output
As already shown, the switching frequency depends on the peak current as well as on the monoflop time for a given
coil. Furthermore it depends on the coil inductance itself.
Due to the principle of switch mode power supplies, the current through the LED is kept constant for any
supply change. The parameter that changes in order to keep the current constant is the switching
frequency itself. The lower the supply voltage, the lower the switching frequency. Furthermore, the supply
current is affected by supply changes: with an increasing supply voltage the average supply current decreases.
The graph below shows the normalised luminous flux versus the power supply for a standard application with one
white Luxeon III LED driven at 750mA. The parameters are optimised for the 24V board net.
The luminous flux at 24V has been set to 100%. The graph indicates that the light output is minimally dependent on
supply changes over the whole range from 16 to 32V.
MLX10803
Normalized luminous flux Θv/Θv(24V) vs. supply voltage
Θv/Θv(24V)=f(VBAT)
120.00
Iled=750mA, fsw=70kHz (@24V)
115.00
110.00
Θv/Θv(24V) [%]
105.00
100.00
95.00
90.00
85.00
80.00
16
3901010803
Rev 022
18
20
22
24
VBAT [V]
Page 20/25
26
28
30
32
Data Sheet
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MLX10803
IC specification
High power LED driver
8.
Temperature regulation
In normal mode the peak current threshold voltage is defined by the lowest voltage on pins VREF, IREF2 and
IREF1. Usually the resistor connected to IREF2 pin has a small thermal coefficient and the resistor on IREF1 pin
has a big negative temperature coefficient (but they also can be connected vice versa). Both of these pins have an
output current of 50 µA. When the voltage on pin IREF1 falls below the voltage on pin IREF2 or VREF, the voltage
reference for the actual maximum current is taken from pin IREF1. This makes the value of the peak current
sensitive to temperature and prevents overheating of LED or IC. When the voltage on pin IREF1 becomes higher
than voltage on IREF2 or VREF, the reference switches back to IREF2 or VREF pin.
The thermal behaviour of the system should be characterised during the design-in of the product by the user.
For a system that is designed for thermal conditions, temperature down regulation may not be needed. In this case,
It is enough to leave the IREF1 or IREF2 pin unconnected and the internal current source will pull it up to the
voltage Vdd – 0.7V.
System behaviour can be configured to compensate the dependency of LED light output versus temperature. The
example of such compensation is depicted below.
3901010803
Rev 022
Relative Current Output (%)
Relative Light Output (%) at 80 °C
Illustration of a possible temperature regulation
Page 21/25
Data Sheet
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MLX10803
IC specification
High power LED driver
9.
Mechanical Data
9.1.
Mechanical data of the MLX10803 package
Package of the MLX10803: SOIC8 in accordance to the JEDEC standard.
D/2
3
2
1
H
E/2
8
TOP VIEW
e
BOTTOM VIEW
h
A
L
oc
Angle 45
A1
DETAIL A
C
D
Ao
E
SEATING PLANE
SEE DETAIL A
SIDEVIEW
END VIEW
DIMENSIONS
A
A1
A0
B
C
D
E
e
H
h
L
oc
X
3901010803
Rev 022
MIN.
.061
.004
.055
.0138
.0075
.189
.150
.230
.010
.016
0°
.085
INCHES
NOM.
.064
.006
.058
.016
.008
.194
.155
.050
.236
.013
.025
5°
.093
Note
MILLIMETERS
MAX
.068
.0098
.061
.0192
.0098
.196
.157
MIN.
NOM.
MAX
1.55
0.127
1.40
0.35
0.19
4.80
3.81
1.73
0.25
1.55
0.49
0.25
4.98
3.99
.244
.016
.035
8°
.100
5.84
0.25
0.41
0°
2.16
1.63
0.15
1.47
0.41
0.20
4.93
3.94
1.27
5.99
0.33
0.64
5°
2.36
Page 22/25
6.20
0.41
0.89
8°
2.54
Degrees
Data Sheet
17/AUG/06
MLX10803
IC specification
High power LED driver
10.
Standard information regarding manufacturability of Melexis products
with different soldering processes
Our products are classified and qualified regarding soldering technology, solderability and moisture sensitivity
level according to following test methods:
Reflow Soldering SMD’s (Surface Mount Devices)
•
•
IPC/JEDEC J-STD-020
Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices
(classification reflow profiles according to table 5-2)
EIA/JEDEC JESD22-A113
Preconditioning of Nonhermetic Surface Mount Devices Prior to Reliability Testing
(reflow profiles according to table 2
Wave Soldering SMD’s (Surface Mount Devices) and THD’s (Through Hole Devices)
•
•
EN60749-20
Resistance of plastic- encapsulated SMD’s to combined effect of moisture and soldering heat
EIA/JEDEC JESD22-B106 and EN60749-15
Resistance to soldering temperature for through-hole mounted devices
Iron Soldering THD’s (Through Hole Devices)
•
EN60749-15
Resistance to soldering temperature for through-hole mounted devices
Solderability SMD’s (Surface Mount Devices) and THD’s (Through Hole Devices)
•
EIA/JEDEC JESD22-B102 and EN60749-21
Solderability
For all soldering technologies deviating from above mentioned standard conditions (regarding peak
temperature, temperature gradient, temperature profile etc) additional classification and qualification tests have to
be agreed upon with Melexis.
The application of Wave Soldering for SMD’s is allowed only after consulting Melexis regarding assurance of
adhesive strength between device and board.
Based on Melexis commitment to environmental responsibility, European legislation (Directive on the
Restriction of the Use of Certain Hazardous substances, RoHS) and customer requests, Melexis has installed a
Roadmap to qualify their package families for lead free processes.
For more information on the lead free topic please see quality page at our website:
http://www.melexis.com/quality_leadfree.asp
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Rev 022
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Data Sheet
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MLX10803
IC specification
High power LED driver
11.
History record
Rev.
1
2
3
4
5
6
7
8
9
10
11
No.
1
1
1
1
1
1
1
1
1
1
1
12
13
14
15
1
1
1
1
16
17
1
1
2
18
19
20
1
2
3
1
1
21
1
22
1
2
3
4
5
3901010803
Rev 022
Change
Creation with MLX10801 specifications as base
Gone through document VAR,ALX,RAH,LIW
4-th pin recast from TEST to VREF - linear dimming
Revision of kick off meeting
Revision before release RAH
Improved packing information RAH
Improved block diagram
Design implementation review
Updated schematic diagrams
Pin order changed
Temperature code changed to “K”, Vmaxdrv changed, Oscillator related parameters
changed, VREF related parameters changed, ROSC related parameters changed
Cosmetic changes
Cosmetic changes
VREF related parameters are changed
Pins’ names changed: RE_REF VREF, NTC IREF1, SETNTC IREF2, VS VS/PWM. Corresponding parameters’ names changed. RSENSE related parameters
changed
LED driver applications changed
Block diagram changed, Electrical characteristics: Global parameters, Monoflop
related parameters, RSENSE related parameters, IREF1 related parameters, IREF2
related parameters, VREF related parameters changed, LED driving principle: The
principle in detail changed
Internal review
Chapter 7.3. changed: graph added, cosmetic changes
Cosmetic changes
Soldering information is changed
Internal review
Monoflop related parameters changed, IREF1, IREF2, VREF related parameters
changed
Figure1, Figure2 changed, 4. Electrical characteristics: changed, 8. Temperature
regulation: figure added
“TBD” removed, cosmetic changes
RESET related parameters changed, ROSC related parameters changed
Cosmetic changes
Chapter 8, Illustration of a possible temperature regulation changed
Cosmetic changes
Page 24/25
Date
25.07.04
02.08.04
07.08.04
7.10.04
15.01.05
16.01.05
3.02.05
13.06.05
17.06.05
21.06.05
12.07.05
3.08.05
18.08.05
21.09.05
23.09.05
23.09.05
28.09.05
31.10.05
28.11.05
6.01.06
23.03.06
6.04.06
6.04.06
14.04.06
16.08.06
17.08.06
Data Sheet
17/AUG/06
MLX10803
IC specification
High power LED driver
12.
Disclaimer
Devices sold by Melexis are covered by the warranty and patent indemnification provisions appearing in its Term of
Sale. Melexis makes no warranty, express, statutory, implied, or by description regarding the information set forth
herein or regarding the freedom of the described devices from patent infringement. Melexis reserves the right to
change specifications and prices at any time and without notice. Therefore, prior to designing this product into a
system, it is necessary to check with Melexis for current information. This product is intended for use in normal
commercial applications. Applications requiring extended temperature range, unusual environmental requirements,
or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not
recommended without additional processing by Melexis for each application.
The information furnished by Melexis is believed to be correct and accurate. However, Melexis shall not be liable to
recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of
profits, loss of use, interrupt of business or indirect, special incidental or consequential damages, of any kind, in
connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or
liability to recipient or any third party shall arise or flow out of Melexis’ rendering of technical or other services.
© 2005 Melexis NV. All rights reserved.
For the latest version of this document, go to our website at:
www.melexis.com
Or for additional information contact Melexis Direct:
Europe and Japan:
All other locations:
Phone: +32 13 61 16 31
E-mail: [email protected]
Phone: +1 603 223 2362
E-mail: [email protected]
ISO/TS16949 and ISO14001 certified
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Data Sheet
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