IXYS Integrated Circuits Division 的 LDS8846 规格书

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LDS8846
© 2009 IXYS Corp. 1Doc. No. 8845DS, Rev. N1.6
Characteristics subject to change without notice
4-Channel Ultra Low Dropout No Noise LED Driver
FEATURES
oUltra-low dropout PowerLite™Current
Regulator*
oDrives up to 4 LEDs at 30 mA each
oPWM brightness control
oPower efficiency > 95%
oLow input noise & ripple
oLow current shutdown mode
oLoad disconnect in shutdown mode
oShort circuit protection
oThermal shutdown protection
oAvailable in 4 x 4 x 0.8 mm and 3 x 3 x 0.8 mm
16-pin TQFN packages
APPLICATION
oKeypad and Display Backlight
oCellular Phones
oDigital Still Cameras
oPDAs and Smartphones
DESCRIPTION
The LDS8846 is a high efficiency ultra-low dropout
current regulator that can drive up to four LEDs. The
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
.
.
TYPICAL APPLICATION CIRCUIT
L11XYS Disglay + | Short Circuit Ou ul Current Limit Vow : 0V ‘ In ut Vo‘ta e : VIN In ut Vo‘ta e = O
LDS8846
© 2009 IXYS Corp. 2Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
ABSOLUTE MAXIMUM RATINGS
Parameter Rating Unit
VIN, LEDx voltage -0.3 to 6 V
VOUT voltage -0.3 to 6 V
EN, CTRL0, CTRL1, CTRL2 voltage VIN + 0.7V V
Storage Temperature Range -65 to +150 °C
Junction Temperature Range -40 to +125 °C
Soldering Temperature (10s) 300 °C
ESD protection HBM 2 kV
NOTE: Stresses listed above may cause permanent damage to thje device. Functional operation of the device at these or any other conditions
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 Rating Unit
VIN 2.7 to 5.5 V
Ambient Temperature Range -40 to +85 °C
ELECTRICAL OPERATING CHARACTERISTICS
(Over recommended operating conditions unless specified otherwise) VIN = 3.6V, EN = High, TAMB = 25°C
Name Conditions Min Typ Max Units
Quiescent Current ILED = 20mA per channel 1.3 1.5 mA
Shutdown Current EN = 0V 0.1 1 µA
RSET = 24k 20
LED Current RSET = 96k 5mA
LED Current Setting Range 2.7 < VIN < 5.5V 2 30 mA
LED Current Accuracy To set value -8 3 +8 %
LED Channel Matching (ILED MAX - ILED MIN) / (ILED
MAX
+ I
LED
MIN
)-5 3 +5 %
Current Sink Dropout Voltage* 20 30 mV
Short Circuit Output Current Limit VOUT = 0V 22 25 mA
High Input Voltage = VIN 1
Leakage Current Low Input Voltage = 0 -1 µA
High 1.3
EN, CTRL0,
CTRL1,
CTRL2 pins Logic Level
Threshold Low 0.4 V
PWM frequency 100 100000 Hz
PWM duty cycle 1 100 %
Thermal Shutdown 150
Thermal Hysteresis 20 °C
Under Voltage Lockout (UVLO)
Threshold
2.4 V
*) Voltage drop at led pin, at which LED current falls 10% below set value
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LDS8846
© 2009 IXYS Corp. 3Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
CONTROL INPUTS FUNCTION
Control Inputs Output States
CTRL2 CTRL1 CTRL0 LED4 LED3 LED2 LED1
0 0 0 OFF OFF OFF ON
0 0 1 OFF OFF ON OFF
0 1 0 OFF ON OFF OFF
0 1 1 ON OFF OFF OFF
1 0 0 OFF OFF ON ON
1 0 1 OFF ON ON ON
1 1 0 ON ON ON ON
1 1 1 OFF OFF OFF OFF
TYPICAL CHARACTERISTICS
VIN = 3.6V, IOUT = 104 mA (4 LEDs at 26 mA each), CIN = COUT = 1 µF, Vf = 3.2 V, TAMB = 25 0C
Power Efficiency vs. Input Voltage LED Current vs. Temperature
LED Current vs. Input Voltage Power-Up Delay Time
V
OUT
ILED
(4 LEDs)
50 mA/div
EN
\LED Cunenl‘ mA 2D 40 6D Duty Cycle, % an mu LED Current Ermr‘ % Duly Cyc‘e, %
LDS8846
© 2009 IXYS Corp. 4Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
Power-Down Delay Time PWM Mode (1 kHz, 50 Duty Cycle)
PWM Mode (10 kHz, 50 Duty Cycle) PWM Mode (50 kHz, 50 Duty Cycle)
ILED Current vs. Duty Cycle ILED Current Error vs. Duty Cycle
CRL0
V
OUT
ILED
(4 LEDs)
50 mA/div
CRL0
V
OUT
ILED
(4 LEDs)
50 mA/div
CRL0
V
OUT
ILED
(4 LEDs)
50 mA/div
EN
V
OUT
ILED
(4 LEDs)
50 mA/div
1 EN Device Enable. 2 CTRLO Output Control Bit 0 (See Table Control Pin Function) 3 CTRL1 Output Control Bit 1 (See Table Control Pin Function) 4 CTRL2 Output Control Bit 2 (See Table Control Pin Function) 5 ISET LED current setting pin 6 VOUT Output voltage to the LED anodes 7 VIN Input Voltage 8 , 11 NC No internal connect 12 PGND Power Ground 13 LED4 LED4 Cathode Terminal 14 LEDS LEDS Cathode Terminal 15 LED2 LED2 Cathode Terminal 16 LED1 LED1 Cathode Terminal PAD PAD Connect to GND on the PCB r m m v o o an m in mm 4 .1 _l_l lfillfillflllfll ENIIF iiiii wlfimuo CTRLDZII IENC | GND I CTRL1ZI: :ENC CTRLZZ‘L ————— AENC GIIElFHEI b—b—Z u 58>; > TQFN3X3§nd4X4 (TOP VIEW)
LDS8846
© 2009 IXYS Corp. 5Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
PIN DESCRIPTION
Pin # Name Function
1 EN Device Enable.
2 CTRL0 Output Control Bit 0 (See Table Control Pin Function)
3 CTRL1 Output Control Bit 1 (See Table Control Pin Function)
4 CTRL2 Output Control Bit 2 (See Table Control Pin Function)
5 ISET LED current setting pin
6 VOUT Output voltage to the LED anodes
7 VIN Input Voltage
8 - 11 NC No internal connect
12 PGND Power Ground
13 LED4 LED4 Cathode Terminal
14 LED3 LED3 Cathode Terminal
15 LED2 LED2 Cathode Terminal
16 LED1 LED1 Cathode Terminal
PAD PAD 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 RSET
connected from this pin to ground controls LED
current. Connect this pin to ground directly for factory
preset LED current value 30 mA.
VIN is the device supply pin. A small 1μF ceramic
bypass capacitor is required between the VIN 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.
VOUT is the charge pump output. Connect it to the
LED anodes. A small 1μF ceramic bypass capacitor
is required between the VOUT 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
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LDS8846
© 2009 IXYS Corp. 6Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
BLOCK DIAGRAM
Figure 2. LDS8846 Functional Block Diagram
BASIC OPERATION
The device starts operating if the EN pin is set logic
HIGH and input voltage is higher that under voltage
protection lockout threshold.
The low dropout PowerLite™Current regulator
performs well at input voltages up to 50 mV greater
than the LED forward voltage significantly increasing
the driver’s efficiency.
Input pins EN, CTRL0, CTRL1, and CTRL2 may be
either logic LOW or HIGH during power-up. However,
logic voltage should never exceed input voltage VIN,
and these pins should not be left float.
LED Current Setting
The desired current value in each of the four LED is
set by external resitor RSET connevted between ISET
pin and ground..
The LED current is 400 times greater than the current
through RSET and can be estimated (in mA) by
following equation:
SET
SET
LED R
V
x
I400,where VSET =1.2V, and RSET is
its resistance in kohms.
RSET value for typical ILED current is shown at the
table below.
ILED, mA RSET, kΩNearest standard 1% value
5 96 95.3
10 48 47.5
15 32 31.6 or 32.4
20 24 23.7 or 24.3
25 19.2 19.1
30 16 15.8 or 16.2
The average current value may be decreased using
PWM signal applied to either CTRL0, CTRL1 or
CTRL2 pin. The LDS8846 allows modulation
frequiencies in the range from 100 Hz to 5 kHz with
duty cycles from 100% to 1% and from 5 kHz to 30
kHz with duty cycles from 100% to 10%. Modulation
frequiencies lower than 100 Hz are not
recommended especialy at short duty cycles because
LED flicker may be visible.
If CTRL1 and CTRL2 pins are logic HIGH and PWM
signal applies to CTRL0 pin, then all four LEDS are
dimming synchronously.
If CTRL0 and CTRL2 pins are logic HIGH and PWM
signal applies to CTL1 pin, then LEDs from LED1 to
LED3 are dimming, while LED4 is always off.
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LDS8846
© 2009 IXYS Corp. 7Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
Unused LED Channels
For applications with only two or three LEDs, unused
LED can be disabled via the appropriate CTRL pins
logic states. For applications requiring 1 LED only,
the unused LED pins should be tied to VOUT.
However, we recommend use of all channels
connecting them in parallel with accordingly
decreased current per channel. If one LED is used
only, current per channel should be decreased four
times, or this device may drive one LED with
maximum current up to 120 mA with all channels
connected in prallel and 30 mA current per chennel.
Figure 3. Application circuit with three LEDs
Figure 4. Application circuit with two LEDs
Figure 5. Application circuit with two LEDs
Figure 5. Application circuit with one LED
Protection Mode
The LDS8846 limits output current if VOUT pin is
shorted to ground either before or after device start.
This is to prevent the device from overload in case of
short circuit at the output. Device resumes normal
operation after short removed.
If the die temperature exceeds +150°C, the driver will
enter thermal protection shutdown mode. When the
device temperature drops by about 20°C, the device
resumes normal operation.
If the input voltage is below under-voltage protection
threshold, device turns into shutdown mode with high
impedance state at VOUT and all LED pins.
LED Selection
LEDs with forward voltages (VF) ranging from 1.3 V to
4.5 V may be used. The device exhibits the highest
efficiency when VFvoltage is close to VIN. If the
voltage source is a Li-ion battery, we recommend
selecting LEDs with VFat least 50 mV below
minimum expected battery discharging voltage to
extend the battery life and achieve highest efficiency.
If the minimum battery discharging voltage is limited
at 3 V, recommended VFvoltage is VF= 3.0 – 0.05 =
2.95 V
External Components
The driver requires only one external component –
current setting resistor RSET. However, if device is
connected to the voltage source (battery) through
long traces, or voltage source has high electrical
noise due bad performance of other components
connected to this source, we recommend 1uF
decoupling capacitors at the VIN and VOUT pins
located as close to he device as possible.
Power dissipates on RSET resistor is less then 100µW
that allows use of very small surface mount
component.
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LDS8846
© 2009 IXYS Corp. 8Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
Recommended Layout
It is recommended to minimize trace length to
decoupling capacitors. A ground plane should cover
the area under the driver IC as well as the bypass
capacitors. Short connection to ground on capacitors
CIN and COUT can be implemented with the use of
multiple vias. A copper area matching the TQFN
exposed pad (PAD) must be connected to the ground
plane underneath. The use of multiple via improves
the package heat dissipation.
Figure 6. LDS8846 Recommended layout
L11 9! DEVICE CODE PM :1 Top View iDENTIFiCATiON 2 x 3 PIN #1 IDENTiFICATiON Mei—LE Rev > CHAMFER H mm x 55° Bottom View A17 A2 , Side View
LDS8846
© 2009 IXYS Corp. 9Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
PACKAGE DRAWING AND DIMENSIONS
16-PIN TQFN, 3mm x 3mm, 0.5mm PITCH
SYMBOL MIN NOM MAX
A 0.70 0.75 0.80
A1 0.00 0.02 0.05
A2 0.178 0.203 0.228
b 0.20 0.25 0.30
D 2.95 3.00 3.05
D1 1.65 1.70 1.75
E 2.95 3.00 3.05
E1 1.65 1.70 1.75
e 0.50 typ
L 0.325 0.375 0.425
m 0.150 typ
n 0.225 typ
Note:
1. All dimensions are in millimeters
2. Complies with JEDEC Standard MO-220
L11XYS Display DDDDDDU DUDE USED 0 PM #1 Top View iDENTiFiCATiON SYMBOL MIN NOM MAX A 0.70 0.75 0.80 A1 0.00 0.02 0.05 A2 0.178 0.203 0.228 b 0.28 0.33 0.38 D 3.90 4 .00 4.10 D1 2.35 2.40 2.45 E 3.90 4.00 4.10 E1 2.35 2 .40 2.45 e 0.65 M) L 0.55 0.60 0.65 E1 Exp Pad . 4% DEViCE CODE 7 4 9 x 3 PIN #1 iDENTIFiCATION Re! CHAMFERUEMSXAS" _ A Bottom View 7 EI—EI—EI—D A1 — A2 _ Side View
LDS8846
© 2009 IXYS Corp. 10 Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
16-PIN TQFN, 4mm x 4mm, 0.65mm PITCH
SYMBOL MIN NOM MAX
A 0.70 0.75 0.80
A1 0.00 0.02 0.05
A2 0.178 0.203 0.228
b 0.28 0.33 0.38
D 3.90 4.00 4.10
D1 2.35 2.40 2.45
E 3.90 4.00 4.10
E1 2.35 2.40 2.45
e 0.65 typ
L 0.55 0.60 0.65
Note:
3. All dimensions are in millimeters
4. Complies with JEDEC Standard MO-220
L11XYS Disglax LDS 8846 002 _} m
LDS8846
© 2009 IXYS Corp. 11 Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
ORDERING INFORMATION
Part Number Package Package Marking
LDS8846 002 -T2 TQFN-16 3 x 3 mm 8846
LDS8846 003 -T2 TQFN-16 4 x 4 mm LDS8846
Notes:
1. Matte-Tin Plated Finish (RoHS-compliant)
2. Quantity per reel is 2000
EXAMPLE OF ORDERING INFORMATION
Notes:
1) All packages are RoHS-compliant (Lead-free, Halogen-free).
2) The standard lead finish is Matte-Tin.
3) The device used in the above example is a LDS8846 002–T2 (3x3 TQFN, Tape & Reel, 32/25/10.5 mA maximum current per LED bank).
4) For additional package and temperature options, please contact your nearest IXYS Corp. Sales office.
Company ID
Package
002: 3x3 TQFN
Prefix Device # Suffix
LDS
8846
002
T2
Product Number Tape & Reel
T: Tape & Reel
2: 2000/Reel
L11XYS Disglay :I'IXYS IXYS Display
LDS8846
© 2009 IXYS Corp. 12 Doc. No. 8846DS, Rev. N1.6
Characteristics subject to change without notice
IXYS Corp.
1590 Buckeye Dr.,
Milpitas, CA 95035-7418
Phone: 408.457.9000 Document No: 8846DS
Fax: 408.496.0222 Revision: N1.6
http://www.ixys.com Issue date: 10/7/2009
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applications and may not be complete.