LDS8846
4-Channel Ultra Low Dropout No Noise LED Driver
FEATURES
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o
o
o
o
o
o
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o
Ultra-low dropout PowerLite™ Current
Regulator*
Drives up to 4 LEDs at 30 mA each
PWM brightness control
Power efficiency > 95%
Low input noise & ripple
Low current shutdown mode
Load disconnect in shutdown mode
Short circuit protection
Thermal shutdown protection
Available in 4 x 4 x 0.8 mm and 3 x 3 x 0.8 mm
16-pin TQFN packages
LED current is easily adjustable by an external
resistor up to 30 mA per channel.
The CTRL0, CTRL1, and CTRL2 logic inputs function
as a LED enable and a PWM mode LED brightness
control.
The driver supports a wide range of input voltages
from 2.7 V to 5.5 V.
The thermal and short circuit protection guarantee
high device reliability.
The device is available in a 16-lead TQFN 4 x 4 mm
and 3 x 3 mm packages with a max height of 0.8 mm
.
.
APPLICATION
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Keypad and Display Backlight
Cellular Phones
Digital Still Cameras
PDAs and Smartphones
DESCRIPTION
The LDS8846 is a high efficiency ultra-low dropout
current regulator that can drive up to four LEDs. The
TYPICAL APPLICATION CIRCUIT
© 2009 IXYS Corp.
Characteristics subject to change without notice
1
Doc. No. 8845DS, Rev. N1.6
LDS8846
ABSOLUTE MAXIMUM RATINGS
Parameter
V
IN
, LEDx voltage
V
OUT
voltage
EN, CTRL0, CTRL1, CTRL2 voltage
Storage Temperature Range
Junction Temperature Range
Soldering Temperature (10s)
ESD protection HBM
Rating
-0.3 to 6
-0.3 to 6
V
IN
+ 0.7V
-65 to +150
-40 to +125
300
2
Unit
V
V
V
°C
°C
°C
kV
NOTE:
Stresses listed above may cause permanent damage to thje device. Functional operation of the device at these or any other conditio ns
beyond those indicated in the “Recommended Operating Conditions” is not impiled. Exposure to abslute maximum rating conditions for
extended periods may remain possibility to affect device reliability.
RECOMMENDED OPERATING CONDITIONS
Parameter
V
IN
Ambient Temperature Range
Rating
2.7 to 5.5
-40 to +85
Unit
V
°C
ELECTRICAL OPERATING CHARACTERISTICS
(Over recommended operating conditions unless specified otherwise) V
IN
= 3.6V, EN = High, T
AMB
= 25°C
Name
Quiescent Current
Shutdown Current
LED Current
LED Current Setting Range
LED Current Accuracy
LED Channel Matching
Current Sink Dropout Voltage*
Short Circuit Output Current Limit
EN, CTRL0,
CTRL1,
CTRL2 pins
Leakage Current
High
Low
High
Low
Conditions
I
LED
= 20mA per channel
EN = 0V
R
SET
= 24k
R
SET
= 96k
2.7 < V
IN
< 5.5V
To set value
(I
LED MAX
- I
LED MIN
) / (I
LED
MAX
+ I
LED MIN
)
Min
Typ
1.3
0.1
20
5
Max
1.5
1
Units
mA
µA
mA
2
-8
-5
3
3
20
30
+8
+5
30
25
1
mA
%
%
mV
mA
µA
V
Hz
%
°C
V
V
OUT
= 0V
Input Voltage = V
IN
Input Voltage = 0
22
-1
1.3
100
1
150
20
2.4
Logic Level
Threshold
PWM frequency
PWM duty cycle
Thermal Shutdown
Thermal Hysteresis
Under Voltage Lockout (UVLO)
Threshold
*) Voltage drop at led pin, at which LED current falls 10% below set value
0.4
100000
100
© 2009 IXYS Corp.
Characteristics subject to change without notice
2
Doc. No. 8846DS, Rev. N1.6
LDS8846
CONTROL INPUTS FUNCTION
Control Inputs
CTRL2
CTRL1 CTRL0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
LED4
OFF
OFF
OFF
ON
OFF
OFF
ON
OFF
Output States
LED3 LED2
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
OFF
OFF
LED1
ON
OFF
OFF
OFF
ON
ON
ON
OFF
TYPICAL CHARACTERISTICS
V
IN
= 3.6V, I
OUT
= 104 mA (4 LEDs at 26 mA each), C
IN
= C
OUT
= 1 µF, Vf = 3.2 V, T
AMB
= 25 C
0
Power Efficiency vs. Input Voltage
LED Current vs. Temperature
LED Current vs. Input Voltage
Power-Up Delay Time
EN
V
OUT
I
LED
(
4 LEDs)
50 mA/div
© 2009 IXYS Corp.
Characteristics subject to change without notice
3
Doc. No. 8846DS, Rev. N1.6
LDS8846
Power-Down Delay Time
EN
CRL0
PWM Mode (1 kHz, 50 Duty Cycle)
V
OUT
V
OUT
I
LED
(4 LEDs)
50 mA/div
I
LED
(4 LEDs)
50 mA/div
PWM Mode (10 kHz, 50 Duty Cycle)
CRL0
CRL0
PWM Mode (50 kHz, 50 Duty Cycle)
V
OUT
V
OUT
I
LED
(4 LEDs)
50 mA/div
I
LED
(4 LEDs)
50 mA/div
I
LED
Current vs. Duty Cycle
I
LED
Current Error vs. Duty Cycle
© 2009 IXYS Corp.
Characteristics subject to change without notice
4
Doc. No. 8846DS, Rev. N1.6
LDS8846
PIN DESCRIPTION
Pin #
1
2
3
4
5
6
7
8 - 11
12
13
14
15
16
PAD
Name
EN
CTRL0
CTRL1
CTRL2
ISET
V
OUT
V
IN
NC
PGND
LED4
LED3
LED2
LED1
PAD
Function
Device Enable.
Output Control Bit 0 (See Table Control Pin Function)
Output Control Bit 1 (See Table Control Pin Function)
Output Control Bit 2 (See Table Control Pin Function)
LED current setting pin
Output voltage to the LED anodes
Input Voltage
No internal connect
Power Ground
LED4 Cathode Terminal
LED3 Cathode Terminal
LED2 Cathode Terminal
LED1 Cathode Terminal
Connect to GND on the PCB
PIN FUNCTION
EN
is a Device Enable. This pin is high impedance.
There should be a pull down resistor <100k when
control signal is floating.
CTRL0, CTRL1, CTRL2
are Output Control Bits
(See Table 2) and PWM LED brightness control logic
inputs. Guaranteed levels of logic high and logic low
are set at 1.3 V and 0.4 V respectively. CTRL0 and
CTRL1 pins are high impedance, and they should be
pull down by resistor <100k when control signal is
floating. CTRL2 pin has internal pull-up resitor ~100k.
ISET
is a LED current setting pin. Resistor R
SET
connected from this pin to ground controls LED
current. Connect this pin to ground directly for factory
preset LED current value 30 mA.
V
IN
is the device supply pin. A small 1
μ
ceramic
F
bypass capacitor is required between the V
IN
pin and
ground at the device. The operating input voltage
range is from 2.7 V to 5.5 V. Whenever the input
supply falls below the under-voltage threshold (2.2
V), all the LED channels are disabled, and the device
enters shutdown mode.
V
OUT
is the charge pump output. Connect it to the
LED anodes. A small 1
μ
ceramic bypass capacitor
F
is required between the V
OUT
pin and ground near the
device.
GND
is the current regulators ground current source.
Connect this pin to the ground plane on the PCB as
close to the package as possible.
LED1 – LED4
provide the internal regulated current
sink for each of the LED cathodes. These pins enter
a high-impedance zero current state when the device
is in shutdown mode.
PAD
is the exposed pad underneath the package.
For best thermal performance, the tab should be
soldered to the PCB and connected to the ground
plane
© 2009 IXYS Corp.
Characteristics subject to change without notice
5
Doc. No. 8846DS, Rev. N1.6
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