8x3-bit Constant Current LED Driver

DD235
Version
: A.003
Issue Date : 2008/02/21
File Name : SP-DD235-A.003.doc
Total Pages : 12
8x3-bit Constant Current LED Driver
新竹市科學園區展業一路 9 號 7 樓之 1
SILICON TOUCH TECHNOLOGY INC.
9-7F-1, Prosperity Road I, Science Based Industrial Park,
Hsin-Chu, Taiwan 300, R.O.C.
Tel：886-3-5645656
Fax：886-3-5645626
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
DD235
8x3-bit Constant Current LED Driver
General Description
DD235 is a 24 channel constant-current sink driver specifically designed for LED decorating
and backlighting applications.
This chip incorporates shift registers, data latches, and constant
current circuitry on the silicon CMOS process.
The constant current values are set by three
external resistors (Rext_R, Rext_G and Rext_B) separately. Each channel can provide a maximum
current of 60mA.
The three enable terminals (EN_R, EN_G and EN_B) supply dimming
applications and control eight channels independently.
Features
z
Maximum constant current output: 60mA
z
Maximum output sustaining voltage: 17V
z
Output enable terminal: 1MHz(max)
z
Power supply voltage: 6V to 18V
z
Over current protection
z
Bit-to-bit skew : ±6% (max)
Chip-to-chip skew : ±10% (max)
Applications
z
LED decorative lamps or bulbs
z
LED backlighting applications
Package Types
z
QFN32 (with exposed pad)
8x3-bit Constant Current LED Driver
Version: A.003
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Page 1
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Pin Connection (Bottom View)
The package of QFN32
Pin Description
PIN NAME
FUNCTION
VDD [1]
Supply voltage terminal
GND [2]
Ground terminal
ENR [6]
Output enable terminals:
‘H’ for all outputs are active ,
‘L’ for all outputs are turned off.
ENG [7]
ENB [8]
REXTR [3]
External resistors connected between REXT and GND for
driver current setting
REXTG [4]
REXTB [5]
OR0~OR7 [9,12,15,18,21,24,27,30]
OG0~OG7 [10,13,16,19,22,25,28,31]
LED driver outputs
OB0~OB7 [11,14,17,20,23,26,29,32]
8x3-bit Constant Current LED Driver
Version: A.003
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Page 2
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Block Diagram
Equivalent Circuit of Inputs and Outputs
1. ENR, ENG, ENB terminals
8x3-bit Constant Current LED Driver
Version: A.003
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Page 3
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Maximum Ratings (Ta=25°C, Tj(max) = 120°C)
CHARACTERISTIC
Supply Voltage
Input Voltage
SYMBOL
RATING
UNIT
VDD
18
V
VIN
5
V
Output Current
IOUT
60
mA
Output Voltage
VOUT
17
V
Input Enable Frequency
FEN
1
MHz
GND Terminal Current
IGND
1500
mA
PD
3.11 ( QFN32 : Ta=25°C)
W
Rth(j-a)
40.6 ( QFN32 )
°C/W
Operating Temperature
Top
-40 ~ 85
°C
Storage Temperature
Tstg
-55 ~ 150
°C
Power Dissipation (4 layer PCB)
Thermal Resistance
Recommended Operating Condition
CHARACTERISTIC
Supply Voltage
Output Voltage
SYMBOL
CONDITION
MIN.
VDD
⎯
6
VOUT
Output Voltage
VOUT
Output Current
IO
VIH
Input Enable Voltage
VIL
Input Enable Frequency
FEN
*1
Driver On
*2
Driver Off
VEN>3V
MAX.
UNIT
18
V
1.0
⎯
0.5VDD
⎯
⎯
17
5
⎯
60
3
⎯
VDD
-0.3
⎯
1
DC
⎯
1
MHz
UNIT
OUT
VDD = 6V ~ 18V
TYP.
V
mA
V
Electrical Characteristics (VDD = 6.0 V, Ta = 25°C unless otherwise noted)
CHARACTERISTIC
Input Voltage “H” Level
SYMBOL
CONDITION
VIH
MIN.
TYP.
MAX.
3
⎯
VDD
-0.3
⎯
1
⎯
⎯
1.0
uA
⎯
⎯
±6
%
±10
%
VDD=6~18V
Input Voltage “L” Level
VIL
Output Leakage Current
IOL
VOH = 17 V
VEN=0V
Output Current Skew
(Channel-to-Channel)
*1
IOL1
VOUT = 1.0 V
Rrext = 5 KΩ
Output Current Skew
(Chip-to-Chip)
*2
V
IOL2
*1
Notice that the power dissipation is limited to its package and ambient temperature.
The driver output voltage including any overshoot stress has to be compliant with the maximum voltage (17V).
*1
Channel-to-channel skew is defined as the ratio between (any Iout – average Iout) and average Iout, where average
Iout = (Imax + Imin) / 2.
*2
Chip-to-Chip skew is defined as the range into which any output current of any IC falls.
*2
8x3-bit Constant Current LED Driver
Version: A.003
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Page 4
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Output Voltage Regulation
Supply Voltage Regulation
Supply Current
Rrext = 5 KΩ
VOUT = 1 V ~ 3 V
⎯
% / VDD
Rrext = 5 KΩ
⎯
IDD(off)
REXT = OPEN,
all outputs off
⎯
REXT=1.5KΩ(Iout=60mA),
all outputs off
⎯
REXT=1.5KΩ(Iout=60mA),
all outputs on
⎯
REXT = 5KΩ (Iout=21mA),
all outputs off
⎯
REXT = 5KΩ (Iout=21mA),
all outputs on
⎯
% / VOUT
IDD(off)
*3
VDD=6V
IDD(on)
VDD=12V
VDD=18V
IDD(off)
IDD(on)
±0.1
±0.5
%/V
±1
±4
4.6
⎯
5.7
7.4
14.6
⎯
15.7
18.6
14.6
⎯
15.7
mA
18.6
4.8
⎯
5.9
7.7
4.8
⎯
5.9
7.7
Switching Characteristics (VDD = 6.0V, Ta = 25°C unless otherwise noted)
CHARACTERISTIC
SYMBOL
CONDITION
Propagation Delay
EN-to-OUT
tpLH
(‘L’ to ‘H’)
VIH = VDD
MIN.
TYP.
MAX.
⎯
40
⎯
UNIT
VIL = GND
Propagation Delay
EN-to-OUT
tpHL
(‘H’ to ‘L’)
*1
45
ns
VL = 1.0 V
Output Current Rise Time
*3
Rrext = 4.17 KΩ
tor
Output Current Fall Time
tof
Output Delay Time (OUT(n)-to-OUT(n+1))
tod
RL = 0 Ω
*1
CL
= 13 pF
⎯
15
⎯
⎯
8
⎯
⎯
0.5
⎯
IO excluded.
CL means the probe capacitance of oscilloscope.
8x3-bit Constant Current LED Driver
Version: A.003
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Page 5
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Timing Diagram
1. EN-OUT
twEN
50%
50%
EN
tor
tof
90%
90%
50%
OUT15
50%
10%
tpLH
(current)
10%
tpHL
2. OUTn+1-OUTn
8x3-bit Constant Current LED Driver
Version: A.003
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Page 6
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Constant-Current Output
Constant-current value of each output channel is set by an external resistor connected between
the REXT pin and GND. Varying the resistor value can adjust the current scale ranging from 5mA to
60mA. The reference voltage of REXT terminal (Vrext) is approximately 1.1V. The output current
value is calculated roughly by the following equation:
Iout (mA) ≅
Vrext (V )
×M
Re xt ( KΩ)
Iout(mA)
5
10
20
30
40
50
60
M
101.4
99.5
97.1
94.6
92.1
89.5
83.1
Output current & Rrext value
70
60
Iout (mA)
50
40
30
20
10
0
0
5
10
15
20
25
30
Rrext (kohm)
Output Current & Output Voltage Curve
70
60
Iout(mA)
50
40
30
20
10
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
Vout(V)
In order to obtain a good performance of constant-current output, a suitable output voltage is
necessary. Users can get related information about the minimum output voltage above.
8x3-bit Constant Current LED Driver
Version: A.003
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Page 7
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Thermal Shutdown
During operation, when the junction temperature of the IC will reach approximately above
180℃, it will cause the driver to shutdown all the outputs. Basically, the IC will cool down and
return to the safe operating temperature which is approximately below 110℃. DM13C will restart
all the outputs at the same time. Operation in the thermal situation for a long time may cause chip
damage permanently.
Typical Application
8x3-bit Constant Current LED Driver
Version: A.003
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Page 8
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Power Dissipation
The power dissipation of a semiconductor chip is limited to its package and ambient
temperature, in which the device requires the maximum output current calculated for given
operating conditions. The maximum allowable power consumption can be calculated by the
following equation:
Pd(max)(Watt) =
Tj(junction temperature)(max)(°C)– Ta(ambient temperature)(°C)
Rth(junction-to-air thermal resistance)(°C/Watt)
The relationship between power dissipation and operating temperature can be refer to the figure
below:
The power consumption of IC can be determined by the following equation and should be less than
the maximum allowable power dissipation:
8x3-bit Constant Current LED Driver
Version: A.003
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Page 9
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
Package Outline Dimension
QFN32
TOP VIEW
BOTTOM VIEW
0.25 C
D2
D
25
32
25
24
8
17
24
1
17
8
L
E
E2
e
1
32
0.25 C
9
16
16
9
e
b
0.10
M
C AB
A
0.10 C
SEATING PLANE
A3
A1
yC
DIMENSIONS IN INCH
DIMENSIONS IN MM
SYMBOLS
MIN.
MAX.
MIN.
MAX.
A
0.028
0.031
0.70
0.80
A1
0
0.002
0
0.05
A3
b
D
D2
E
E2
0.010TYP.
0.007
y
0.18
0.197TYP.
0.049
0.128
0.049
0.128
0.020
0.012
0.30
5.00TYP.
3
0.197TYP.
e
L
0.012
0.25TYP.
3.25
5.00TYP.
3
3.25
0.50TYP.
0.020
0.004TYP.
0.30
0.50
0.10TYP.
Note: 1.DIMENSIONING AND TOLERANCING CONFORM TO ASME Y145.5M-1994.
2. REFER TO JEDEC STD. MO-220 WHHD-2 ISSUE A
8x3-bit Constant Current LED Driver
Version: A.003
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Page 10
點晶科技股份有限公司
DD235
SILICON TOUCH TECHNOLOGY INC.
The products listed herein are designed for ordinary electronic applications, such as
electrical appliances, audio-visual equipment, communications devices and so on. Hence,
it is advisable that the devices should not be used in medical instruments, surgical
implants, aerospace machinery, nuclear power control systems, disaster/crime-prevention
equipment and the like. Misusing those products may directly or indirectly endanger
human life, or cause injury and property loss.
Silicon Touch Technology, Inc. will not take any responsibilities regarding the misusage
of the products mentioned above. Anyone who purchases any products described herein
with the above-mentioned intention or with such misused applications should accept full
responsibility and indemnify. Silicon Touch Technology, Inc. and its distributors and all
their officers and employees shall defend jointly and severally against any and all claims
and litigation and all damages, cost and expenses associated with such intention and
manipulation.
8x3-bit Constant Current LED Driver
Version: A.003
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Page 11