YOBON YB1303

YB1303
Low Dropout LED Driver
Description
Features
The YB1303 provides a simple solution for
driving three channels of any color LEDs
with current matching ability. The ultra low
dropout LED driver features higher peak
efficiency and very low shutdown current.
The LED current can be adjusted by an
external resistor or the control voltage. The
YB1303 can work independently or
combine with any boost converters which
need to have current matching function for
LED drivers. The YB1303 is available in
6-pin tiny SC70-6 package.
„ LED Drivers for Parallel Connected
„
„
„
„
„
LEDs
Only One External Resistor is Needed
PWM and Analog Brightness Control
No EMI and Switching Noise
Power Saving Shutdown Mode (<0.1μA)
Small Footprint SC70-6 Package
Applications
„ LCD Display Modules
„ Keyboard Backlight
„ PDA, DSC, MP3 players
„ LED Displays
„ Handheld Computers
„ Cell Phones
Typical Application Circuit
Figure 1: Typical Application Circuit
YB1303 Rev.1.0
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YB1303
Low Dropout LED Driver
Pin Configuration
CTR
1
6
EN
LED2
2
5
LED3
LED1
3
4
GND
SC70-6
Figure 2: Pin Configuration
Pin Assignment &Description
Table 1
Pin
Name
Description
1
CTR
Connect this pin with a resistor to set the LED current.
2
LED2
Connect this pin to LED cathode.
3
LED1
Connect this pin to LED cathode.
4
GND
Ground pin.
5
LED3
Connect this pin to LED cathode.
6
EN
Connect this pin to logic high to enable this chip, logic low to
disable this chip.
Ordering Information
Table 2
Order Number
Package Type
Supplied As
Package Marking
YB1303SC76A
SC70-6
3000 Units Tape & Reel
Please contact sales
representative
YB1303 Rev.1.0
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2
YB1303
Low Dropout LED Driver
Absolute Maximum Ratings
Recommended Operating Conditions
LED1, LED2, LED3 to GND ........ -0.3V to 6V
EN to GND.................................. -0.3V to 6V
CTR to GND ............................... -0.3V to 3V
Power Dissipation by SC70-6 TA=85℃........133mW
Junction Temperature Range...............150℃
Storage Temperature Range .....-55℃ to 150℃
Lead Temperature................................250℃
ESD HBM .......................................... 1.5KV
ESD CDM ...........................................750V
LED Cathode Voltage ................. 0.3V to1V
Operating Temperature.........-40℃ to 85℃
Electrical Characteristics
Table 3
(VIN=3.3 to 5.5V, VEN=3V, TA=25°C, unless otherwise noted. VF is LED forward voltage.)
Description
Symbol
LED Cathode Voltage
VCATHODE
Output Current Multiplication
Factor
Test Conditions
ISET = 100μA,
VLED = 300mV
MIN
TYP
MAX
Units
0.3
0.5
1
V
140
200
260
1
Shutdown Current
ISD
VEN = 0V
0.1
LED Current
ILED
ISET = 100μA
20
-3
LED to LED Current Matching
Efficiency
η
VIN =3.3V,
(VIN – VCATHODE) / VIN
SHDN Logic Low Level
VIL
ILED < 1μA
SHDN Logic High Level
VIH
ISET = 100μA
YB1303 Rev.1.0
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mA
+3
90
%
%
0.5
3
μA
V
V
3
YB1303
Low Dropout LED Driver
Typical Performance Characteristics
VIN=3.3 to 5.5V, VEN=3V, TA=25°C, unless otherwise noted. VF is LED forward voltage.
LED Current vs. LED Cathode Voltage
Iset vs. Control Voltage
(Vcontrol=3V, VEN=3V)
(RSET=17.4k, Vcathode=0.3V)
22
160
20
140
LED Current (mA)
120
100
Iset (uA)
Rset=17.4k
Iset=100uA
18
80
60
40
16
14
12
10
8
6
4
20
2
0
0.00
0
0.0
0.5
1.0
1.5
2.0
Vcontrol (V)
2.5
3.0
3.5
4.0
0.20
0.40
0.60
1.00
1.20
1.40
1.60
1.80
2.00
2.20
Cathode Voltage (V)
LED Current vs. Enable Voltage
LED Current vs. Rset
(Vcontrol=3V, Vcathode=0.3V, Rset=17.4k)
(VEN=3V, Vcontrol=3V)
22
45
20
40
18
35
LED Current (mA)
16
LED Current (mA)
0.80
14
12
10
8
6
30
Vcathode=0.3
25
Vcathode=0.5
Vcathode=1
20
15
10
4
5
2
0
0
0
1
2
3
VEN Voltage (V)
4
5
Control Voltage Transient Response
YB1303 Rev.1.0
6
0
10
20
30
40
Rset (kOhms)
50
60
70
80
Enable Voltage Transient Response
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YB1303
Low Dropout LED Driver
Application Information
voltage. The lower the VLED voltage, the
higher the system efficiency. The system
efficiency can be calculated as follows:
Analog Dimming Control Table
Table 4
VEN=3V, VCONTROL=3V
ILED (mA)
5
10
15
20
25
RSET (kΩ)
75
34
24
17.4
13
Efficiency = (VIN-VCATHODE) / VIN
Thermal Considerations
At any given ambient temperature, the
maximum package power dissipation can
be determined by the following equation:
Table 5
VEN=3V, RSET=17.4k
ILED (mA)
5
10
15
20
25
PD(MAX) = [TJ(MAX)-TA] / θJA
VCONTROL (V)
1.5
2.1
2.5
3
3.6
Setting the LED Current
The LED current can be set by the control
voltage and the RSET resistor from the
following equation.
Constraints for the YB1303 are maximum
junction temperature TJ(MAX)=125 ℃ , and
package thermal resistance, θJA=300℃/W.
The maximum total LED current for
YB1303 depends on package power
dissipation and the LED cathode voltage at
TJ(MAX). At 85℃, PD(MAX)=133mW. At TA =
25℃, PD(MAX)=333mW.
The maximum current is calculated by the
following equation:
ILED=200×(VCONTROL-VCTR)/RSET
The suggested values and relations
between VCONTROL and RSET can also be
found in the diagram of typical
characteristics and table 4 and table5. The
LED brightness can be controlled by either
the above equation or applying a PWM
signal to the EN pin. The driving signal
frequency should be greater than 100Hz to
avoid flickering, and increased to more
than 1MHz if necessary.
Efficiency Considerations
The YB1303 featured low drop out can
achieve excellent efficiency performance.
The efficiency is mainly dominated by VLED
YB1303 Rev.1.0
ILED < (PD(MAX) / VLED(MAX))
For example, if ILED = 60mA, and TA = 85℃,
VLED(MAX) = 2.2V.
If the ambient temperature were to
increase, the internal die temperature
would increase, and the device would be
damaged.
Application Examples
The ultra-low voltage drop across the
YB1303 allows the devices to drive white,
blue and any color LEDs in a wide range of
input voltages. The driver can be used in
many applications presented in this
document, due to their similar operation.
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YB1303
Low Dropout LED Driver
Example 1:
Drive low VF white or blue LEDs directly
from single cell Li-Ion battery
Example 2:
Drive high VF white or blue LEDs from
exiting bus from 4.0V to 6V
When using white or blue low VF LEDs,
and utilizing the driver’s low voltage drop,
only 3.4V in VIN is needed for the full 20mA
LED current. At 3.2V, there is still 5mA
typical current available for the LEDs. The
single cell Li-Ion battery is utilized in many
applications like cell-phones and digital still
cameras. In most cases, the Li-Ion battery
voltage level only goes down to 3V, and not
down to the full discharged level (2.7V)
before requesting the charger.
High VF white or blue LEDs have forward
voltage drop in the range of 3.2V to 4.0V.
To drive these LEDs with the maximum
current of 20mA for maximum brightness,
usually requires a boost circuit for a single
cell Li-Ion voltage range. In some cases,
there is already a voltage bus in the system,
which can be utilized. Due to the ultra-low
voltage drop of the YB1303 to drive high VF
white or blue LEDs, the VIN needs to be
only 300mV higher than the highest VF in
the circuit.
-VDROP < 0.3V
-VF (@20mA) < 3.1V (Low VF)
-VIN (@20mA) = -VDROP+VF=3.4V
-VDROP < 0.3V
-VF (@20mA) < 3.3V to 4.0V (High VF)
-VIN (@5mA typical) ~3.1V
Where VIN = Single cell Li-Ion Voltage
Key advantages:
y No boost circuit needed for the LCD or
keyboard backlight.
y Drivers directly connected to a Li-Ion
battery.
y No EMI, no switching noise, no boost
efficiency lost, no capacitor and no
inductor.
YB1303 Rev.1.0
-VIN (@20mA) = -VDROP+VF=3.6V to 4.3V
-VIN (@5mA typical) ~3.3V
Where VIN = Existing bus = 3.3V to 4.3V
Key advantages:
y No boost circuit needed for the LCD or
keyboard backlight.
y Driver utilizes the existing bus.
y Ultra-low voltage drop provides the full
20mA LED current at the lowest possible
voltage level.
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YB1303
Low Dropout LED Driver
Example 3:
Drive white, blue, red, amber LEDs
string
Assuming boost circuit, or existing voltage
bus, the YB1303 can be used to drive a
whole string of LEDs and flexible
brightness control – whether using analog
or PWM (Notes).
LED Brightness Control
The YB1303 LED drivers feature analog
and PWM controls to give designers
flexible brightness control. These control
methods can be applied to the circuit in two
different ways which provide flexible
solution. To determine the value of RSET,
use the “ISET vs. VCTR” graph under the
“typical characteristics” section.
Scenario 1 - Analog
-VDROP < 0.3V
-VIN_MIN = N×VF + VDROP
- VIN_MAX = N×VF + 6V
-VIN (@5mA typical) ~3.3V
Where VIN = Existing Bus / Boost Voltage
Key advantages:
y No need for current matching resistors
and discrete transistor for brightness
control.
Set VCONTROL and RSET for LED current
ILED=200×(VCONTROL-VCTR)/RSET
Scenario 2 – PWM - 1
ILED=200×(VCONTROL-VCTR)/RSET
VCONTROL = PWM
y Amplitude sets maximum LED current
y Pulse width controls between 0 and
maximum
Notes:
Scenario 3 – PWM - 2
1. Whether using analog or PWM signal, please
ILED ~ 200×ISET
notice to avoid from exceeding the absolute
maximum rating claimed in this document.
2. EN must be turned on prior to VIN (delivered by
boost circuit or existing bus) and avoid from
VIN > 6V when EN is off.
YB1303 Rev.1.0
VEN = PWM
y Amplitude has no effect on current
y Pulse width controls between 0 and
maximum
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YB1303
Low Dropout LED Driver
Package Information (SC70-6)
NOTICE:
y The information described herein is subject to change without notice.
y Yobon does not assume any responsibility for use of any circuitry or applications described herein, nor
does it convey any patent license.
YB1303 Rev.1.0
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