W-52 [NIDEC]
CMOS White LED Driver;
| 型号： | W-52 |
| 厂家： | 
NIDEC COMPONENTS |
| 描述： | CMOS White LED Driver |
| 文件： | 总11页 (文件大小：194K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
W-52
CMOS White LED Driver
Description
The W-52 is a DC/DC step up converter that delivers a regulated
output current. Operation at a constant switching frequency of
1.2 MHz allows the device to be used with very small value external
inductor and ceramic capacitors.
The W-52 is targeted to drive multiple white lightïemitting diodes
(LEDs) connected in series and provides the necessary regulated current
to control the brightness and the color purity. An external resistor RSET
controls the output current level. LED currents of up to 40 mA can be
supported over a wide range of input supply voltages from 2 V to 7 V,
making the device ideal for batteryïpowered applications.
A high voltage output stage allows up to 4 White LEDs to be driven
in series. Series drive provides inherent current matching.
LED dimming can be done by using a DC voltage, a logic signal, or
a pulse width modulation (PWM) signal. The shutdown input pin
allows the device to be placed in powerïdown mode with “near zero”
quiescent current.
In addition to overcurrent limiting protection, the device also
includes detection circuitry to ensure protection against openïcircuit
load fault conditions.
The device is available in a low profile (1 mm max height) 6ïlead
TSOTï23 package.
1
TSOTï23
PIN CONNECTIONS
1
VIN
SW
GND
LED
SHDN
RSET
TSOTï23
1 mm Maximum Height
= 250oC/W (free air)
JA
(Top View)
Features
v Low Quiescent Ground Current (0.5 mA Typical)
v Power Efficiency Over 80%
v Compatible Pinout with LT1932
MARKING DIAGRAMS
v Adjustable Output Current (up to 40 mA)
v High Frequency 1.2 MHz Operation
v Input Voltage Operation down to 2.0 V
v Low Resistance (0.5 ) High Voltage Power Switch
v Drives up to 4 White LEDs in Series
v Shutdown Current Less than 1 A
VFYM
VFꢀ=ꢀW-52TDIꢀïGT3
Y = Production Year (Last Digit)
M = Production Month (1ï9, A, B, C or O, N, D)
v Load Fault Protection Against Openïcircuits
v Low Value External Components
ORDERING INFORMATION
v Low Profile (1 mm) TSOTï23 6ïlead Package
v These Devices are PbïFree, Halogen Free/BFR Free and are RoHS
Compliant
Device
Package
Shipping
TSOTï23
(PbïFree)
3,000/
Tape & Reel
W-52TDIꢀï*T3
(Note 1)
Applications
1.
v Color LCD and Keypad Backlighting
v Cellular Phones
NiPdAu Plated Finish (RoHSïcompliant).
v Handheld Terminals
v Digital Cameras
v PDAs/Games
v Portable MP3 Players
¢ NIDEC COPAL ELECTRONICS CORP.ꢀ
'HFHPEHU,ꢀ20ꢁꢂꢀïꢀRev. ꢂ
1
Publication Order Number:ꢀ
W-52/(
W-52
Typical Application Circuit
D1
L
1
6.8
H
VIN
2.7 V
to
C1: Taiyo Yuden JMK212BJ475
C2: Taiyo Yuden EMK212BJ105
D1: Zetez ZHCS400
L1: Sumida CLQ4D106R8
(Panasonic ELJEA6R8)
4.2 V
C1
4.7
F
1
6
VIN
SW
W-52
PWM
3
5
C2
1
DIMMING
SHDN
RSET
LED
GND
2
F
CONTROL
15 mA
4
R
SET
1.50 k
TSOTï23 Pin Numbers
Figure 1. LiïIon Driver for Four HighïBrightness White LEDs
Table 1. PIN DESCRIPTION
Pin Number
SOT23
Name
Function
1
SW
Switch pin. This is the drain of the internal power switch. For minimum EMI, min-
imize the trace area connected to this pin.
2
3
4
GND
LED
Ground pin. Connect pin 2 to ground.
LED (cathode) connection pin.
RSET
RESET pin. A resistor connected from pin 4 to ground sets the LED current. This
pin is also used to dim the LEDs.
5
6
SHDN
VIN
Shutdown pin.
Input supply pin. This pin should be bypassed with a capacitor to ground. A
4.7 F capacitor mounted close to the pin is recommended.
2
W-52
Table 2. ABSOLUTE MAXIMUM RATINGS
Parameter
Rating
Unit
V
V , LED, SHDN voltage
IN
8
SW voltage
20
1
V
RSET voltage
V
Storage Temperature Range
Junction Temperature
ï65 to +150
125
$C
$C
$C
V
Lead Soldering Temperature (10 secs)
ESD Rating – Human Body Model
300
2000
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
Table 3. RECOMMENDED OPERATING CONDITIONS
Parameter
Range
2 to 7
Unit
V
V
IN
Ambient Temperature Range
Inductor L1
ï40 to +85
$C
H
6.8 (20% typical
4.7 (20% typical
1.0 (20% typical
0 to 20
Input Capacitor C1
Output Capacitor C2
F
F
I
with 1 to 4 LEDs in series
mA
LED
NOTE: Typical application circuit with external components is shown on page 2.
Table 4. ELECTRICAL OPERATING CHARACTERISTICS
(Over recommended operating conditions unless otherwise specified. T = 25$C, V = 2 V and V
= 1.2 V.)
A
IN
SHDN
Symbol
Parameter
Quiescent Current
Conditions
Min
Typ
Max
0.7
1
Unit
I
Q
V
RSET
= 0.2 V
0.5
0.05
120
mA
A
I
Ground Current in Shutdown
LED Pin Voltage
V
SHDN
= 0 V
GND
V
V
IN
< V
, I
= 15 mA
180
40
mV
mA
mA
LED
LED
LED
OUT LED
I
I
LED Current Adjust Range
Programmed LED Current
5
33
R = 562
SET
38
30
45
R
= 750
25
36
SET
SET
R
= 1.5 k
12.5
15
17.5
R
= 4.53 k
= 15 mA
= 1.5 k
5
SET
I
LED Pin Current Temperature Coefficient
RSET Pin Voltage
I
ï0.01
100
mA/$C
mV
V
LED
LED
V
RSET
R
SET
Shutdown Pin Logic High Level
Shutdown Pin Logic Low Level
Boost Converter Frequency
Switch Current Limit
0.85
0.25
1.6
780
1.2
0.9
5
V
f
0.8
1.2
550
0.7
MHz
mA
SW
I
400
SWL
R
Switch Resistance
V
= 2 V, I
= 3 V, I
= 100 mA
= 100 mA
SW
IN
SW
V
IN
0.5
SW
Switch Leakage Current
Efficiency
Switch Off, V
= 5 V
0.01
83
A
SW
Components shown on Figure 1
%
3
W-52
TYPICAL CHARACTERISTICS
(V = 3.6 V, T
IN
= 25$C, C = 4.7 F, C
OUT
= 1 F, L = 6.8 H, unless otherwise specified.)
AMB
IN
600
500
400
600
VIN = 7 V
500
VIN = 2 V
400
300
200
300
200
2
2
2
3
4
5
6
7
ï50
ï25
0
25
TEMPERATURE ($C)
Figure 3. Quiescent Current vs. Temperature
50
75
100
125
INPUT VOLTAGE (V)
Figure 2. Quiescent Current vs. Input Voltage
2.0
1.6
1.2
0.8
2.0
1.6
1.2
0.8
0.4
0
0.4
0
3
4
5
6
7
ï50
ï25
0
25
50
75
100
125
INPUT VOLTAGE (V)
TEMPERATURE ($C)
Figure 4. Switching Frequency vs. Input
Voltage
Figure 5. Switching Frequency vs.
Temperature
35
30
25
20
15
10
20
15
10
R
= 750
SET
R
SET
= 1.13 k
R
R
= 1.50 k
= 2.26 k
SET
SET
5
0
5
0
3
4
5
6
7
ï50
ï25
0
25
TEMPERATURE ($C)
Figure 7. LED Current vs. Temperature
50
75
100
125
INPUT VOLTAGE (V)
Figure 6. LED Current vs. Input Voltage
4
W-52
TYPICAL CHARACTERISTICS
(V = 3.6 V, T
IN
= 25$C, C = 4.7 F, C
OUT
= 1 F, L = 6.8 H, unless otherwise specified.)
AMB
IN
1.0
0.8
0.6
0.4
1.0
0.8
0.6
V
IN
= 3 V
0.4
0.2
0
0.2
0
2
0
2
3
4
INPUT VOLTAGE (V)
Figure 8. Switch Resistance vs. Input Voltage
5
6
ï50
ï25
0
25
TEMPERATURE ($C)
Figure 9. Switch Resistance vs. Temperature
50
75
100
125
300
250
200
150
100
50
0
8
16
24
32
40
LED CURRENT (mA)
Figure 10. LED Pin Voltage vs. LED Current
Figure 11. V , I , & V
Signal Waveforms
SW
L
OUT
85
80
75
70
4 LEDs at 15 mA
V
OUT
= 13 V
65
60
3
4
INPUT VOLTAGE (V)
Figure 12. Efficiency vs. Input Voltage
5
6
Figure 13. PWM on SHDN Pin Waveform
5
W-52
Operation
The W-52 device is a high efficiency, constant
frequency, current regulating boost converter.
While maintaining LED current regulation, the W-52
automatically adjusts the LED pin voltage to be as low as
possible. A low LED pin voltage ensures high efficiency.
Current through the internal power switch is continuously
monitored cycleïbyïcycle. If the current limit is exceeded,
the switch is immediately turned off, protecting the device,
for the remainder of the cycle.
The device includes a switch and an internally
compensated loop for the regulation of the LED current.
Operation can be best understood by examining the block
diagram. The RSET pin is regulated at 100 mV and the
current through the external resistor will set the regulated
current in the LEDs (from 5 mA to 40 mA) with a
multiplication factor of 225.
PWM dimming operation can be achieved by switching
the SHDN pin or by pulling the RSET pin higher than 0.1 V.
Block Diagram
L
1
D
1
V
IN
C
2
1
SW
C
1
Over Voltage
Protection
1.2 MHz
(22 V)
Oscillator
LED
ï
I
LED
3
PWM
& Logic
+
+
Current
Sense
Amp
ï
100 mV
V
IN
6
5
Current
Control
I
= 225 x I
S
LED
SHDN
225x
I
S
W-52
GND
RSET
2
4
R
SET
Figure 14. W-52 Block Diagram
6
W-52
Application Information
Inductor Selection and Efficiency
Inductor vendors are shown below. Contact the manufacturer for detailed technical data and new product information.
Table 5. INDUCTOR MANUFACTURERS
Maximum
Height (mm)
Inductor
L ( H)
Maximum DCR (m )
Vendor
Web
ELJEA4R7
4.7
180
250
2.2
2.2
Panasonic
714.373.7334
www.panasonic.com
ELJEA6R8
6.8
LQH3C4R7M24,
LQH32CN4R7M11
LQH3C100K24,
LQH32CN100K11
LB2016B4R7
4.7
10
260
300
2.2
2.2
Murata
770.436.1300
www.murata.com
www.tïyuden.com
www.sumida.com
4.7
3.8
4.7
6.8
4.7
6.8
250
350
216
296
162
195
2.0
2.0
0.8
0.8
1.2
1.2
Taiyo Yuden
408.573.4150
LB2016B100
CMD4D06ï4R7
CMD4D06ï6R8
CLQ4D10ï4R7
CLQ4D10ï6R8
Sumida
847.956.0666
Capacitor Selection
Diode Selection
Low ESR (equivalent series resistance) capacitors should
be used at the output to minimize the output ripple voltage.
The low ESR and small package options available with
multilayer ceramic capacitors make them excellent choices.
The X5R and X7R capacitor types are preferred because
they retain their capacitance over wider voltage and
temperature ranges than the Y5V or Z5U types. A 1.0 F or
2.2 F output capacitor is recommended for most
applications.
Schottky diodes, with their low forward voltage drop and
fast switching speed, are the ideal choice for high efficiency
applications. Table 7 shows several different Schottky
diodes that work well with the W-52. Make sure that the
diode has a voltage rating greater than the output voltage.
The diode conducts current only when the power switch is
turned off (typically less than oneïthird the time), so a 0.4 A
or 0.5 A diode will be sufficient for most designs.
Table 7. SCHOTTKY DIODE SUPPLIERS
The voltage rating of the output capacitor C2 depends on
the number of LEDs driven in series. A 10 V ceramic
capacitor is recommended when driving two LEDs. A 16 V
ceramic capacitor is recommended when driving 3 or 4
LEDs.
Part
Supplier
MBR0520
MBR0530 s
MBR0540
ZHCS400
ON Semiconductor
www.onsemi.com
800.282.9855
Table 6. CERAMIC CAPACITOR MANUFACTURERS
Zetex
Supplier
Taiyo Yuden
Murata
Phone
Web
408.573.4150
814.237.1431
408.986.0424
www.tïyuden.com
www.murata.com
www.kemet.com
LED Current Programming
The LED current is programmed with a single resistor
connected to the RSET pin. The RSET pin is internally
regulated to 100 mV, which sets the current flowing out of
this pin, ISET, equal to 100 mV/RSET. The W-52 regulates
the current into the LED pin, ILED, to 225 times the value of
ISET. For the best accuracy, a 1% or better resistor is
recommended. Table 8 shows several typical 1% RSET
values.
Kemet
Low profile ceramic capacitors with a 1 mm maximum
height/thickness are available for designs height
requirements. Ceramic capacitors also make a good choice
for the input capacitor, which should be mounted as close as
possible to the W-52. A 2.2 F or 4.7 F input capacitor is
recommended. Table 6 shows a list of several ceramic
capacitor manufacturers. Consult the manufacturers for
detailed information as new products and package options
are introduced regularly.
7
W-52
In addition to providing the widest dimming range, PWM
Table 8. R
RESISTOR VALUES
SET
(mA)
brightness control also ensures the “purest” white LED color
over the entire dimming range. The true color of a white
LED changes with operating current, and is the “purest”
white at a specific forward current, usually 15 mA or
20 mA. If the LED current is less than or more than this
value, the emitted light becomes more blue. Applications
involving color LCDs can find the blue tint objectionable.
When a PWM control signal is used to drive the SHDN pin
of the W-52, the LEDs are turned off and on at the PWM
frequency. The current through them alternates between full
current and zero current, so the average current changes with
duty cycle. This ensures that when the LEDs are on, they can
be driven at the appropriate current to give the purest white
light. LED brightness varies linearly with the PWM duty
cycle.
I
R
SET
LED
40
562
30
25
20
15
10
5
750
909
1.13 k
1.50 k
2.26 k
4.53 k
For other LED current values, use the following equation
to choose RSET
.
0.1 V
ILED
RSET
255
Most white LEDs are driven at maximum currents of
15 mA to 20 mA. Some higher power designs will use two
parallel strings of LEDs for greater light output, resulting in
30 mA to 40 mA (two strings of 15 mA to 20 mA) flowing
into the LED pin.
LED Dimming with a Logic Signal
For applications that need to adjust the LED brightness in
discrete steps, a logic signal can be used. RMIN sets the
minimum LED current value (when the NMOS is OFF):
0.1 V
ILED(MIN)
RMIN
255
LED Dimming with PWM Signal
PWM brightness control provides the widest dimming
range (greater than 20:1). By turning the LEDs ON and OFF
using the control signal the LEDs operate at either zero or
full current, but their average current changes with the PWM
signal duty cycle. Typically, a 5 kHz to 40 kHz PWM signal
is used. PWM dimming with the W-52 can be
accomplished two different ways.
RINCR determines how much LED current increases when
the external NMOS switch is turned ON.
0.1 V
ILED(Increase)
RINCR
255
LED Dimming with a DC Voltage
The SHDN pin can be driven directly or a resistor can be
added to drive the RSET pin. If the SHDN pin is used,
increasing the duty cycle will increase the LED brightness.
Using this method, the LEDs can be dimmed and turned off
completely using the same control signal. A 0% duty cycle
signal will turn off the W-52, reducing the total quiescent
current to near zero.
If the RSET pin is used, increasing the duty cycle will
decrease the brightness. Using this method, the LEDs are
dimmed using RSET and turned off completely using
SHDN. If the RSET pin is used to provide PWM dimming,
the approximate value of RPWM should be calculated (where
VMAX is the “HIGH” value of the PWM signal):
VMAX 0.1 V
ILED(MAX) ILEAD(MIN)
RADJ
225
PCB Layout Guidelines
The W-52 is a highïfrequency switching regulator and
therefore proper PCB board layout and component
placement can minimize noise and radiation and increase
efficiency. To maximize efficiency, the W-52 design has
fast switch rise and fall times. To prevent radiation and high
frequency resonance problems minimize the length and area
of all traces connected to the SW pin and use a ground plane
under the switching regulator.
The switch, schottky output diode and output capacitor
signal path should be kept as short as possible. The ground
connection for the RSET resistor should be tied directly to the
GND pin and not be shared with other components.
VMAX
0.15 V
RPWM
RSET
1
W-52
W-52
W-52
W-52
W-52
RSET
4
SHDN
5
RSET
4
RSET
4
RSET
4
R
PWM
PWM
PWM
V
DC
PWM
R
ADJ
R
10 k
R
PWM
Logic
INCR
R
R
R
R
SET
MIN
SET
SET
0.1
F
Signal
Figure 15. LED Dimming Circuits
8
W-52
TYPICAL APPLICATION CIRCUITS
(The application diagrams below are shown for the TSOTï23 packages.)
D1
L
1
6.8
H
VIN
6
VIN
1
SW
W-52
C1
4.7
C2
2.2
5
3
F
SHDN
LED
F
GND
2
RSET
4
15 mA
2.5 V DC 60.40 k
DIMMING
CONTROL
R
SET
1.50 k
Figure 16. Two LEDs with DC Level Dimming Control
D1
L
1
6.8
H
VIN
85
80
75
70
V
= 4.2 V
IN
6
1
V
IN
= 3.0 V
VIN
SW
W-52
C2
1
C1
4.7
5
3
SHDN
F
LED
GND
2
F
RSET
4
15 mA
60.40 k
2.5 V DC
DIMMING
CONTROL
65
60
R
1.50 k
SET
0
5
10
LED CURRENT (mA)
Figure 18. Efficiency ï Three LEDs
15
20
Figure 17. Three LEDs with DC Level Dimming Control
D1
L
6.8
1
H
VIN
85
80
75
70
V
IN
= 4.2 V
V
C1
4.7
F
= 3.0 V
IN
6
VIN
1
SW
W-52
PWM
C2
1
5
3
DIMMING
SHDN
RSET
4
LED
GND
2
CONTROL
F
15 mA
65
60
R
SET
1.50 k
0
5
10
15
20
LED CURRENT (mA)
Figure 20. Efficiency ï Four LEDs
Figure 19. Four LEDs with PWM Dimming Control
9
W-52
PACKAGE DIMENSIONS
TSOTï23, 6 LEAD
CASE 419AFï01
ISSUE O
SYMBOL
MIN
NOM
MAX
1.00
0.10
0.90
0.45
0.20
D
A
A1
A2
b
e
0.01
0.80
0.30
0.12
0.05
0.87
c
0.15
D
2.90 BSC
2.80 BSC
1.60 BSC
0.95 TYP
0.40
E1
E
E
E1
e
L
0.30
0.50
L1
L2
e
0.60 REF
0.25 BSC
0º
8º
TOP VIEW
A2 A
A1
L
b
c
L2
L1
SIDE VIEW
END VIEW
Notes:
(1) All dimensions are in millimeters. Angles in degrees.
(2) Complies with JEDEC MO-193.
10
W-52
Example of Ordering Information (Note 5)
Prefix
Device #
Suffix
W
-
52
TD
I
ï G
T3
Company ID
(Optional)
Product Number
Package
TD: TSOTï23
Temperature Range
I = Industrial
(ï40oC to +85oC)
Lead Finish
G: NiPdAu
Tape & Reel
T: Tape & Reel
3: 3,000 / Reel
52
3. All packages are RoHSïcompliant (Leadïfree, Halogenïfree).
4. The standard lead finish is NiPdAu.
5. The device used in the above example is a W-52TDIïGT3 (TSOTï23, Industrial Temperature Range, NiPdAu, Tape & Reel, 3,000 / Reel).
NIDEC COPAL reserves the right to make changes without further notice to any products herein.
NIDEC COPAL makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does NIDEC COPAL assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.
“Typical” parameters which may be provided in NIDEC COPAL data sheets and/or specifications can and do vary in different applications and actual performance may vary over time.
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NIDEC COPAL does not convey any license under its patent rights nor the rights of others.
NIDEC COPAL products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to
support or sustain life, or for any other application in which the failure of the NIDEC COPAL product could create a situation where personal injury or death may occur.
Should Buyer purchase or use NIDEC COPAL products for any such unintended or unauthorized application, Buyer shall indemnify and hold NIDEC COPAL and its officers,
employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly,
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manufacture of the part.
W-52/(
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ETC
W-6137
CMOS Boost ConverterWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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NIDEC
W-6137TD-G3
CMOS Boost ConverterWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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NIDEC
W-6137TD-GT
CMOS Boost ConverterWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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NIDEC
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