DEI1090-MES-G [DEIAZ]
LED Driver with Square-Law Dimming Control;
| 型号： | DEI1090-MES-G |
| 厂家： | 
Device Engineering Incorporated |
| 描述： | LED Driver with Square-Law Dimming Control 驱动 接口集成电路 |
| 文件： | 总13页 (文件大小：321K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Device
Engineering
Incorporated
DEI1090
LED Driver with Square-Law
Dimming Control
6031 South Maple Ave.
Tempe, AZ 85283
Phone: (480) 303-0822
Fax: (480) 303-0824
E-mail: admin@deiaz.com
FEATURES
·
·
·
·
·
·
·
Emulates incandescent lamp ‘Square Law’ luminance curve.
LED dimming controlled by Pulse Width Modulation ranging from 50HZ to 200HZ.
Maximum LED current adjustable from 10mA to 20mA.
200:1 Dimming Range at 50Hz. 40:1 Dimming Range at 200Hz
Drives 8 LED outputs with matched current drive.
Drivers can be cascaded to synchronously drive additional LEDs.
Package Options
o
o
Plastic 16 lead SOIC
20L QFN 5 X 5
APPLICATIONS
·
·
·
LED replacement for dimmable incandescent lamps.
Avionics instrument and panel lighting.
Balanced display and keyboard backlighting.
GENERAL DESCRIPTION
DEI1090 device is a 16 pin bipolar integrated circuit designed to drive eight LEDs and provide Pulse Width Modulated (PWM)
dimming control according to the luminance curve of incandescent lamps. All eight LEDx pins are driven with an average current
proportional to the square of the input dimming voltage to control the LED brightness. Drivers can be cascaded to synchronously
drive additional LED groups. The dimming control input may be a DC or AC voltage.
Table 1 – SOIC Terminal Description
PIN
1
NAME
VDD
DESCRIPTION
POWER INPUT: +4.5 to +16.5 VDC
ANALOG INPUT: 0 to 2.5V AC or DC analog input for
brightness control.
2
3
VIN
1
16
VDD
VIN
ENABLE
PWM
LED8
LED7
LED6
LED5
ISET
ANALOG IO: Optional external filter resistor and capacitor
used when 400HZ AC control signals are supported. This pin
must be connected to ground through a resistor even in DC
FILT
FILT
LED1
LED2
LED3
FSET
GND
LED DRIVE OUTPUT: LED cathode connection. LED
4-6,9,
11-14
LED1-8
FSET
average current is proportional to the square of VIN.
ANALOG INPUT: External capacitor input to set PWM
frequency.
7
POWER INPUT: Ground.
8
GND
ISET
LED4
ANALOG INPUT: External resistor input to set LED current.
10
ANALOG OUTPUT: PWM output drives multiple 1090 slave
devices for synchronous operation.
15
16
PWM
LOGIC INPUT: HIGH enables operation. LOW sets all LED
outputs OFF and sets standby state.
ENABLE
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2
1
3
4
5
20
19
18
17
6
7
8
9
10
16
15 14 13 12 11
BOTTOM VIEW
Table 1A – QFN Terminal Description
PIN
3
NAME
VDD
DESCRIPTION
POWER INPUT: +4.5 to +16.5 VDC.
ANALOG INPUT: 0 to 2.5V AC or DC analog input for brightness
control.
4
5
VIN
ANALOG IO: Optional external filter resistor and capacitor used
when 400HZ AC control signals are supported. This pin must be
connected to ground through a resistor even in DC applications.
FILT
LED DRIVE OUTPUT: LED cathode connection. LED average
current is proportional to the square of VIN.
6, 8, 9, 14, 16,
17, 18, 19
LED1-8
FSET
ANALOG INPUT: External capacitor input to set PWM frequency.
11
7, 12, 13, 20
PAD
POWER INPUT: Ground.
GND
ISET
ANALOG INPUT: External resistor input to set LED current.
15
ANALOG OUTPUT: PWM output drives multiple 1090 slave
devices for synchronous operation.
1
2
PWM
LOGIC INPUT: HIGH enables operation. LOW sets all LED
outputs OFF and sets standby state.
ENABLE
No Connect
10
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FUNCTIONAL DESCRIPTION
Top Level
Figure 1 is the top level diagram of the DEI1090 Square Law LED Dimmer. The input voltage from a dimming bus is scaled at
the VIN control pin to a range between 0 and 2.5V. The load on the dimming bus is kept to a minimum since the DEI1090 is locally
powered through the VDD pin.
A peak detector/filter is provided to allow use of either a DC or AC control input. The optional filter is set by an external resistor
and capacitor at the FILT pin. A resistor load must be used even in DC applications. (Recommended 100kΩ)
The ENABLE pin enables the part when high and must be tied to VDD when not used. When the ENABLE pin is low, the part is
put into a standby state and all LEDs are set to off.
Eight LED driver outputs are provided. Each is driven with a Pulse Width Modulated (PWM) current waveform that has an average
current proportional to the square of the voltage at the VIN pin. The PWM frequency is set with an external capacitor at the FSET
pin. The peak LED current at 100% duty cycle is a multiple of the Iset current which is set with an external resistor at the ISET
pin.
The PWM pin is provided to allow cascading multiple DEI1090s to expand the number of synchronously controlled LED driver
output.
Figure 1 - DEI1090 Simplified Block Diagram
Input Filter and Peak Detector
An external resistor divider is used to scale the voltage applied to the VIN pin providing interface to a variety of standard avionics
dimming bus formats i.e. 0-5VDC, 0-5VAC, 0-28VDC as showing in Table . The VIN interface contains a peak detector and a
filter circuit to allow 400HZ AC control input signals. The external filter connections are shown in Figure 1. When an AC input is
used, Rfilt and Cfilt should be set up to filter 400 Hz into DC. The signal to the FILT pin is limited to an internal 2.5V reference.
A resistor load (Rfilt in the figure) must be used for the FILT pin even in DC applications.
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Dimming Control
The DEI1090 VIN control signal ranges from 0V to 2.5V full scale. This controls the PWM duty cycle and the LED current to
produce an average current proportional to the square of the control voltage. The square-law characteristic equations are shown
below and the resulting LED average current vs. VIN curve is shown in Figure 2.
The square-law curve includes a 0.5V typical onset voltage (Vos) where LED illumination begins. When VIN is below Vos, the
LEDs are off (Iled < Ioff) which emulates the behavior of an incandescent lamp. The current gain (Igain) from the ISET pin to the
LEDx output pins is typically around 24 for a 5V system.
ì
ï
ï
ï
í
0
if Vin <Vos
é(Vin - Vos)ù
Iled(peak) =
* Igain if Vin >Vos and < 2.5V
ê
ú
Rset
ë
û
ï
ï
(2.5V - Vos)
é
ù
* Igain
if Vin > 2.5V
ê
ú
ï
Rset
ë
û
î
0 %
if Vin <Vos
ifVin >Vos and < 2.5V
if Vin > 2.5V
ì
ïï (Vin -Vos)
Iled(dutycycle) =
ïí(2.5V -Vos)
ï
100%
î
ì
ï
ï
0
if Vin < Vos
2
é
ù
(
Vin -Vos)
ï
Iavg =
* Igain if Vin >Vos and < 2.5V
í
ëê(2.5V -Vos)* Rset
ú
û
ï
ï
(2.5V -Vos)
é
ù
* Igain
ifVin > 2.5V
ï
ê
ú
Rset
ë
û
î
1200
Imean
Imean-ideal
1000
800
600
400
200
0
0
0.5
1
1.5
2
2.5
3
3.5
-200
Figure 2 - Square-Law Relationship of VIN vs. Iled Average
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APPLICATION INFORMATION
Setting PWM Frequency
The PWM frequency can be set with an external capacitor (Cfset) as shown in Figure 1. The PWM frequency is determined by:
Ifset
PWM frequency =
;
where Cfset is in uF and Ifset is in uA
2*Cfset
For example, to set the frequency to 120Hz nominal with a 12 uA charging current, Cfset should be 0.05 mF. The serrodyne
waveform will be seen at the FSET pin and is buffered to the PWM output. In most cases the actual frequency will be slightly
lower since the reset of the serrodyne (ramp generator) is not instantaneous.
Figure 3 - PWM Serrodyne Waveform
Cascading Multiple Drivers
Multiple drivers can be cascaded by connecting the PWM pin to the FSET pin of one slave device. If more than two are required,
daisy chain the next PWM to the next FSET pin. The PWM output waveform is a buffered Serrodyne signal as generated at the
FSET pin.
Figure 4 - Cascading Multiple Drivers
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Setting Up Your Input and Filter
Many dimmer applications use a 400 Hz AC source for the dimming voltage. The brightness of the incandescent lamp is
proportional to the RMS value of the AC signal. As an added feature, the DEI1090 has an input peak detector and allows for an
external filter to be added so that AC dimming signals can be used to create a proportional DC voltage. The input is also limited at
this stage to an on-chip 2.5V reference value.
All applications require an input divider to bring the signal to a level that is suitable for the DEI1090 device. After the input is half
wave rectified and peak detected, then it is sent to the FILT pin where a filter should be placed to remove ripple from the signal.
The input resistors R1 and R2 shown in Figure 5 should be set up as shown in Table 2.
Input Type
R1
1.83 * R
R
R2
R
R
Comments
R should be at least 10K ohms to protect the chip from
5V AC Dimming Voltage
5V DC Dimming Voltage
28V DC Dimming Voltage
clamp current when an AC signal is used.
10.2 * R
R
Table 2 - Resistor Ratios for Scaling Dimmer Voltages
Example of Rset Determination
Rset
Iset max
417 uA
500 uA
583 uA
667 uA
749 uA
833 uA
Iled max *
10 mA
12 mA
14 mA
16 mA
18 mA
20 mA
Rset is selected to set the peak current value at 100% duty
cycle. A fixed resistor or trimmer may be used to set the LED
current for the required luminance at full scale Vin. The peak
LED current range is from 10 mA and 20 mA. Resistor values
should be set as shown in Table 3.
4.80 kΩ
4.00 kΩ
3.43 kΩ
3.00 kΩ
2.67 kΩ
2.40 kΩ
Note: To measure or adjust the peak current, drive Vin > 2.5V
and < VDD.
* - Iled max in the table assumes a gain of 24.
Table 3 - Rset versus LED Maximum Current
Creating a Dual Range Dimmer
To create a dual range dimmer with two dimming curves, the
circuit can be set up to switch a second Rset resistor in parallel
with the primary Rset resistor.
An example is shown in Figure 5. This uses Rset = 4.8 kΩ
resistor in parallel with Rset2 = 4.8 kΩ resistor and a switch.
When the switch is open, Rset = 4.8 kΩ and the maximum LED
current is ~ 10 mA. When the switch is closed, the equivalent
resistance of 2.4 kΩ creates a maximum peak current of ~ 20 mA.
Note: To measure the peak current, drive Vin > 2.5V and < VDD.
Figure 5 - Dual Range LED Dimmer Example
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LED Output Compliance Voltage and Power Consumption
The DEI1090 regulates current through eight LED outputs. Each LEDx output can regulate LED current over a wide compliance
voltage range. The voltage at the LED pin should be designed to be as low as possible to minimize power dissipation in the IC.
Figure 6 shows typical LED output I-V characteristics for various Iset values.
0.025
Iset
Current
0.02
(uA)
0.015
833u
729u
625u
521u
417u
0.01
0.005
0
0
1
2
3
4
5
LEDx Output Voltage (V)
Figure 6 – Output I-V Characteristics
As is shown in Figure 6, an output voltage above 0.7V will regulate the output current.
Example calculation of IC power dissipation. Use Figure 1:
Given that the voltage across the LED is 2V and the current through each LED is 20 mA and there is 1 LED per output, Vdd supply
is +12V, V+ is +5v and Iq (VDD quiescent current, see Table 6) is 3.5ma and the optional RLED resistors aren’t being used, the
average IC power dissipation due to the LED drive is:
Pd = Pq + Pld = Iq * Vdd + 8 * Iout * Vout = 3.5mA * 12v + 8 * 20 mA * (5v-2v) = 42mw + 480mw = 522mw
Pd must be kept below the maximum power listed in Table 4 to keep the junction temperature < Tjmax. Pd should be minimized
for optimum IC reliability.
Assuming a Theta-ja (junction to ambient rise with power) of 74C/W, the junction temperature is .522 x 74 = 38.6C above
ambient temperature.
One way to control the IC power dissipation is to place a resistor in
series with the LED as shown in Figure 1. This will drop the
24.5
excess V+ voltage in the resistor rather than in the IC.
24
Voltage Dependency of Igain
23.5
23
The gain from Iset to Iled is nominally about 24. This gain has a
supply voltage dependency so that the gain at VDD = 15V is higher
than the gain when VDD = 5V. The minimum and maximum gain
values for some common operating voltages are listed in Table 6.
An example waveform of the linear voltage dependency is shown
in Figure 7. Note: All LED outputs of the IC should be loaded.
The part will still work with outputs unloaded but the current
calculation may be skewed. For example, if four LED’s are to be
run at 20ma each, the Iset should be set to 10ma and the LED’s
paralleled in groups of two in order to use up all eight outputs.
22.5
6
8
10
12
14
16
VDD/V
2V/div
Figure 7 - Voltage Dependency Curve
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Adjusting Onset Voltage and Gain Curve
The LED onset voltage (Vos) is used to match the turn-on voltage of an
incandescent lamp. If an application requires a Vos lower than the 0.5V
Vos of the IC, an offset voltage may be added to the Vin input making
the apparent turn-on voltage lower. As shown in Figure 8, the VDD is
added in through Ros which is a much higher value than R1 and R2.
As an example :
Vos is typically 0.5V
Choose R1 = R2 = 10 kΩ (5V DC Dimming Voltage)
If an onset voltage of 0.25 V is desired then, using the equation:
Figure 8 – Vos reduction example
R2 Ros
R1 R2
Vin =V dim mer*
+VDD*
R1+ (R2 Ros)
Ros + (R1 R2)
1
Use Ros = 100 kΩ, then Vin @ V dim mer * +VDD*0.05.
2
This results in about an extra 0.25 V for a 5V supply and an apparent 0.25V onset voltage from the dimming bus. This onset
voltage will vary with VDD.
Some applications might require a higher onset voltage. For example, the circuit in Figure 9 works with an input range of 9v
through 28v to produce an equivalent .5v to 2.5v range at Vin of the IC. The zener diode in this example is 4.7v. The break point
is set by D1 while the slope is set by the resistors.
Figure 9 Vos elevation example
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The schematic in Figure 10 provides two break points using diodes D1 and D2 that allow manipulating the curve to something
other than the square law curve. Zener diode D1 is 4.7v and D2 is 20v. Input voltage range is 9v to 28v for a Vin on the IC of
.5v to 2.5v.
Figure 10 Piecewise transfer curve modification example
Slew Rate Control
The current through the LED can be limited when required. A 10us rise and fall time would require a minimum 50 mH inductor
in series with the set resistor on the ground side. Place a diode in parallel with the inductor from ground to the top pin in order to
clamp negative going pulses to one diode drop below ground.
ELECTRICAL DESCRIPTION
Table 4 - Absolute Maximum Ratings
PARAMETER (Voltages referenced to Ground)
VDD Supply Voltage
MIN
MAX
+20
UNITS
V
Storage Temperature
Input Voltage
-65
+150
°C
FSET, ISET, ENABLE, PWM pins
VIN pin (during AC dimmer operation, keep absolute current below 1 mA)
LED1-8 pins
– 0.3
– 0.6
– 0.3
VDD+0.3
VDD+0.3
20
V
V
Input Current: Any pin
-20
20
mA
Power Dissipation @ 85 °C: (> 10 Sec)
16 Lead SOIC
ESD per JEDEC A114-A Human Body Model
700
2000
mW
V
°C
Peak Body Temperature,
Non-G Package
-
240
260
- G Package
Notes: Stresses above absolute maximum ratings may cause permanent damage to the device.
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Table 5 - Recommended Operating Conditions
PARAMETER (Voltages referenced to Ground)
VDD Supply Voltage
MIN
MAX
UNITS
+4.5
+16.5
V
Operating Temperature
Plastic Package
Junction Temperature:
-55
+85
°C
°C
+125
Tjmax, Plastic Packages (Limited by molding compound Tg)
Table 6 - Electrical Characteristics
Conditions: Temperature: -55°C to +85°C for plastic, VDD = 4.5 to 16.5V Unless otherwise noted.
25°C (4)
-55°C (4)
85°C (4)
(or over temp range)
PARAMETER
CONDITIONS
SYMBOL
UNITS (1)
MIN NOM MAX MIN NOM MAX MIN NOM MAX
SUPPLY CURRENT
ENABLE = 0.0 V,
VDD=16.5V
ENABLE=VDD=
16.5V;
VIN = 0.0 V;
All LEDs off
VDD Standby Current
VDD Quiescent Current
Istdby
8
50
6
15
5
30 100
uA
Iq
2.5
5
3.25
3.5
5
mA
PULSE WIDTH MODULATOR
VIN at 100% PWM Duty
Cycle
VIN at PWM Onset
Voltage
VAPWM
Vos1
2.4 2.45 2.5
0.4 0.5 0.6
V
V
FSET charge current
FSET = 0V
IFSET
11 13.3 15 13 15 16 13 14.2 16
mA
PWM Output Voltage
Accuracy from FSET
Voltage (5)
Cascaded
DEI1090
PWMacc
-3 0.3
3
%
VIN BUFFER/PEAK DETECTOR/ FILTER
VIN Input Voltage Range
VIN Input Current
VIN
Iin
0
2.5
V
VIN = 0V to 2.5V
-10 -5
uA
Input Buffer Accuracy
(DC)
VIN/Vfilt
VIN = 1.0v
BufAcc
VFILT
-3 0.5
0
3
%
V
FILT Output Voltage
VIN = 0 to 2.5V
2.5
LOGIC INPUT
ENABLE Input Low
ENABLE Input High
Vil
Vih
Iil
0.4
0.4
0.4
V
V
2.4
2.4
2.4
ENABLE Input Current
Low
ENABLE Input Current
Hi
ENABLE =
Vilmax
ENABLE =
Vihmin
-5 -1.8
-5 -1.75
uA
Iih
uA
LED DRIVER
VSET
ISET Bias Voltage @
100% Duty Cycle
LED Output Minimum
Compliance Voltage (2)
VIN = 2.5V
ILED = 20mA
2.0
0.7
V
V
VCOMP
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Conditions: Temperature: -55°C to +85°C for plastic, VDD = 4.5 to 16.5V Unless otherwise noted.
25°C (4)
-55°C (4)
85°C (4)
(or over temp range)
PARAMETER
CONDITIONS
SYMBOL
UNITS (1)
MIN NOM MAX MIN NOM MAX MIN NOM MAX
LED Output Off State
Leakage Current
VIN = 0V, LEDx
= 5V
0.01
0.05
0
IOFF
mA
Pin-to-PIN LED Output
current matching, relative
to median
VDD = 5V, 12V,
15V (3)
IMATCH
±6
14
±5
±4
%
VDD = 5V (3)
VDD = 12V (3)
VDD = 15V (3)
VDD = 5V (3)
VDD = 12V (3)
VDD = 15V (3)
ILED5L
ILED12L
ILED15L
ILED5H
ILED12H
ILED15H
9
9
13
16
16
7
8
8
11
11
12
18
20
20
mA
mA
mA
mA
mA
mA
Current Gain: Iset =
400uA
12
12
15
19
20
17 11
17 12
21 16
26 17
27 17
20 14
23 16
23 16
Current Gain: Iset =
800uA
Notes:
1. Currents flowing into the device are positive. Currents flowing out of the device are negative. Voltages are referenced to
ground.
2. Guaranteed by design.
3. LEDx = 1V, VIN = 2.5V, FSET = 0.5V
4. If no -55C or 85C limits are stated, 25C limits apply at all temperatures.
5. Applies to SES part only. MES part TBD.
PACKAGE DESCRIPTION
Table 7 – Package Characteristics
PACKAGE TYPE
20 QFN 5X5 G
16 Lead WB SOIC - G
REFERENCE
20 QFN 5X5 G
16 Lead WB SOIC - G
THERMAL RESISTANCE:
qJA (4 layer PCB with Power Planes)
~ 37 °C/W (see note)
74 °C/W
24 °C/W
~ 7 °C/W
qJC
JEDEC MOISTURE
SENSITIVITY LEVEL
MSL 1 / 260°C
MSL 1 / 260°C
(MSL)
LEAD FINISH MATERIAL /
JEDEC Pb-free CODE
NiPdAu
NiPdAu
e4
Pb-Free DESIGNATION
RoHS Compliant
RoHS Compliant
JEDEC REFERENCE
MO-153-AC
Note: Exposed pad soldered to PCB land with thermal vias to internal ground plane.
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16 Lead WB SOIC, -G Package
DIMENSION IN INCHES
SYM
A
A1
A2
b
c
D
E1
E
MIN
0.098
0.005
0.089
0.012
0.008
0.402
0.291
0.400
NOM
0.101
0.009
0.092
0.016
0.010
MAX
0.104
0.012
0.095
0.020
0.013
0.410
0.299
0.414
0.406
0.295
0.404
e
L
L1
θ
0.050 Typical
--
0.016
0.051
0°
0.050
0.059
8°
0.055
--
h
0.010
0.015
0.020
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20 Lead QFN 5X5, -G Package
Dimension
mm
mils
Symbol
A
Min
0.85
0
0.175
4.9
4.9
3.15
3.15
Max
0.95
0.05
0.225
5.1
5.1
3.25
3.25
Min
33.46
0
Max
37.40
1.97
A1
A3
D
E
D2
E2
6.89
8.86
192.91
192.91
124.02
124.02
200.79
200.79
127.95
127.95
e
0.65BSC
0.25
0.35
0°
25.59BSC
NX b
NX L
0.35
0.45
4°
9.84
13.78
17.72
4°
13.78
0°
θ°
ORDERING INFORMATION
Part Number
DEI1090-MES-G
Marking
DEI1090
MES
Package
20 QFN 5X5 G
Temperature
-55 ºC to +85 ºC
DEI1090-SES-G
DEI1090
E4
16 WB SOIC
-55 ºC to +85 ºC
DEI reserves the right to make changes to any products or specifications herein. DEI makes no warranty, representation, or
guarantee regarding suitability of its products for any particular purpose.
© 2019 Device Engineering Incorporated
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