ETC T6326A

tm
TE
CH
Preliminary T6326A
Low-Dropout, Constant-Current
White LED with Channel Control
FEATURES
GRNERAL DESCRIPTION
• Up to 400mA LED Bias Current
• 3% LED Current Matching
• Simple LED Brightness Control
• Low 0.05uA Shutdown Current
• 3V to 5.5V Supply Voltage Range
• MSOP-10L Package
• Output channel :
MSOP-10L package for four channel
• LED1~4 Channels ON / OFF states:
T6326A-AM with 16 channel states
T6326A-BM with 5 channel states
• Build in Thermal Protect 140 °C
The T6326A low-dropout bias supply for
white LEDs is a high-performance alternative
to the simple ballast resistors used in
conventional white LED designs. The T6326A
with internal channel on/off select function.
The T6326A uses a single resistor to set the
bias current for four LEDs, which are matched
to 3%. The T6326A advantages over ballast
resistors include significantly better LED to
LED bias matching, much lower bias variation
with supply voltage variation, significantly
lower dropout voltage, and in some
applications, significantly improved efficiency.
The T6326A is available in MSOP-10L
package.
Applications
• Cellular Phones
• Portable Communication Devices
• Handheld Electronics
• Digital Cameras
• PDAs
• LED/Display Back Light Driver
• LEDs for Camera Flash
PART NUMBER EXAMPLES
PART NO.
PACKAGE
ON states
T6326A-AM
MSOP-10L
16
T6326A-BM
MSOP-10L
5
TM Technology Inc. reserves the right
P. 1
to change products or specifications without notice.
Publication Date: FEB. 2006
Revision: A
tm
TE
CH
Preliminary T6326A
PIN ARRANGEMENT(Top view)
VSET
1
10
CH SW
LED1
2
9
EN
LED2
3
8
VDD
LED3
4
7
VSS
LED4
5
6
VSS
MSOP-10L
PIN DESCRIPTION
SYMBOL
MSOP
-10L
VSET
1
LED1
2
LED2
3
LED3
4
LED4
5
VSS
VDD
EN
CHSW
6,7
8
9
10
DESCRIPTION
VSET terminal is used to connect an extermal resistor to set output current.
The current flowing into VSET sets the bias current into each LED by ILED_= 250 x ISET.
VSET is internally biased to 0.306V. VSET is high impedance when EN is low.
LED 1 Cathode Connection. Current flowing into LED1 is 250 times the current
flowing into SET. LED1 is high impedance when EN is low.
LED 2 Cathode Connection. Current flowing into LED1 is 250 times the current
flowing into SET. LED2 is high impedance when EN is low.
LED 3 Cathode Connection. Current flowing into LED1 is 250 times the current
flowing into SET. LED3 is high impedance when EN is low.
LED 4 Cathode Connection. Current flowing into LED1 is 250 times the current
flowing into SET. LED4 is high impedance when EN is low.
Ground
Power supply
Enables T6326A signal, H: Ative, L : Power Down .
Set LED1~4 Channels ON / OFF, the rising edge of CHSW will change next states.
TM Technology Inc. reserves the right
P.2
to change products or specifications without notice.
Publication Date: FEB. 2006
Revision: A
tm
TE
CH
Preliminary T6326A
ABSOLUTE MAXIMUM RATINGS
Parameter
Symbol
Value
Unit
Voltage on any pin relative to GND
VIN
-0.3 to 6
V
Operating Temperature Rang
TA
-40 to +85
°C
TLEAD
300
°C
TS
-65 to +150
°C
1
W
Maximum Soldering Temperature (at leads, 10 sec)
Storage Temperature Rang
Continuous Power Dissipation ( TA = +70°C )
Electrical Characteristics
(TA = -40 to 85°C unless otherwise noted. Typical values are at TA =25°C,
VEN =3.3V, VLED1 = VLED2= VLED3= VLED4= 1V)
Symbol
Description
Conditions
EN is power supply input
Min. Typ. Max
VEN
Operating voltage range
ISET
SET input current range
ISETR
SET to LED current ratio
ILED / ISET, ISET=400uA
VSET
SET bias voltage
ISET=400uA
ICM
LED to LED current matching ISET=400uA
ILED
Maximum LED sink current
Each LED
ILSD
LED leakage current in
shutdown
VIH
Input high voltage
VLED1=VLED2=VLED3=VLED4= 3.3V,
EN=GND, TA=+25°C, each LED
VEN >VIH for enable, VDD=5V
2.5
VIL
Input low voltage
VEN <VIL for disable, VDD=5V
TTP
Thermat Protect
TM Technology Inc. reserves the right
P.3
to change products or specifications without notice.
3
5.5
Unit
V
1400 1600
uA
250
A/A
0.306
V
3
%
350
400
mA
0.01
1
uA
V
2.2
140
V
°C
Publication Date: FEB. 2006
Revision: A
tm
TE
CH
Preliminary T6326A
Functional Description
Applications Information
The T6326A provides constant current bias
supply for white LED designs. The T6326A
uses a single resistor to set the bias current for
up to three LEDs. LED bias currents are
matched to 3% by the T6326A current
matching architecture (Fig. 1). The T6326A
offers several advantages over using ballast
resistors, such as improved LED to LED
brightness matching, lower bias variation with
supply voltage changes, significantly lower
dropout voltage, and in some applications,
significantly improved efficiency.
Very Low-Cost, High-Efficiency Solution .
A battery (single Li+ or three NiMH cells)
powers the LEDs directly. This is the least
expensive and most efficient architecture. Due
to the high forward voltage of white LEDs,
the LED brightness may dim slightly at the
end of battery life. The T6326A current
regulating architecture and low dropout
greatly minimize this effect compared to
using simple ballast resistors. The enable
function of the T6326A turns on and off the
LEDs.
Enable Input
EN powers the input of the T6326A. Drive
EN high (> 2.5V) to enable the device; drive
EN low (< 2.2V) to disable the device.
Driving EN low forces LED1, LED2, LED3,
LED4 and SET into a high-impedance state.
CHSW Input
The Set LED1~4 Channels ON / OFF , the
rising edge of CHSW will change next states.
The T6326A with Internal SEL pad Channel
function select.
The T6326A-AM with 16 channel states:
LED[1:4]=[1111],[1110],[1101],[1100],
[1011],[1010],[1001],[1000],
[0111],[0110],[0101],[0100],
[0011],[0010],[0001],[0000]
The T6326A-BM with 5 channel states :
LED[1:4]=[1111],[1110],[1100],[1000],[0000]
Setting the Output Current
SET controls the LED bias current. Current
flowing into LED1, LED2, LED3 and LED4
is 250 times greater than the current flowing
into SET. Set the output current as follows:
ILED = 250 (VSET / RSET )
VSET = 0.306V
TM Technology Inc. reserves the right
P.4
to change products or specifications without notice.
Publication Date: FEB. 2006
Revision: A
tm
TE
CH
Preliminary T6326A
TYPICAL APPLICATION CIRCUITS
V+
VDD
VDD
ON
OFF
LED1
LED2
LED3
LED4
EN
CHSW
SET
GND
R
Very low-cost, high-efficiency solution
TM Technology Inc. reserves the right
P.5
to change products or specifications without notice.
Publication Date: FEB. 2006
Revision: A
tm
TE
CH
Preliminary T6326A
PACKAGE DIMENSIONS
10-LEAD MSOP-10L
B
B1
K
T h e rm a l P a d *
A1
J
C1
A
C
C2
F
D
Symbol
A
A1
B
B1
C
C1
C2
D
E
F
J
K
H
Min.
0.75
0.00
0.17
0.40
0.10
-
Dimension in mm
Typ.
4.90
3.00
3.00
0.50
0.85
0.60
0.15
1.715 REF
1.600 REF
0~8°
E
H
Max.
1.10
0.95
0.15
0.27
0.80
0.25
-
Min.
0.029
0.000
0.007
0.015
0.004
-
Dimension in inch
Typ.
0.193
0.118
0.118
0.019
0.033
0.024
0.006
0.067 REF
0.063 REF
0~8°
Max.
0.043
0.037
0.006
0.010
0.031
0.010
-
*Note :
The thermal pad on the IC’s bottom has to be mounted on the copper foil.
To eliminate the noise influence, the thermal pad is suggested to be connected to GND on PCB.
In addition, desired thermal conductivity will be improved, if a heat-conducting copper foil on
PCB is soldered with thermal pad. The thermal pad enhances the power dissipation. As a result, a
large amount of current can be sunk safely in one package.
TM Technology Inc. reserves the right
P.6
to change products or specifications without notice.
Publication Date: FEB. 2006
Revision: A