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PDF NCP5021 Data sheet ( Hoja de datos )
| Número de pieza | NCP5021 | |
| Descripción | LED Driver | |
| Fabricantes | ON Semiconductor | |
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NCP5021www.DataSheet4U.com
High Voltage White LED
Driver with Ambient Light
Sensing
The NCP5021 product is a single output boost LED driver capable
of driving up to 8 LEDs in series for portable backlight applications.
The built−in DC/DC converter is based on a high efficient PWM
boost structure with 32 V output voltage span. It provides a peak 90%
efficiency together with a 1% I−LED current tolerance.
Features
• 2.7 to 5.5 V Input Voltage Range
• 90% Peak efficiency with 4.7 mH / 150 mW Inductor
• Gradual Dimming Built−in (Automatic Fade In/Fade Out Effect)
• Integrated Ambient Light Sensing Automatically Adjusts the LCD
Backlight Contrast
• Built−in Zero Current Load Leakage under Idle Mode
• Support the Full I2C Protocol with Address Extension
• Tight 1% I−LED Tolerance
• Ultra Thin 0.5 mm QFN16 Package
• This is a Pb−Free Device
Typical Applications
• Cellular Phone, Smartphone
• Portable Media Player (PMP)
• Global Positioning System (GPS)
+Vbat
L1
NSR0240M2T5G
GND C1
4.7mH
D8
4.7mF/6.3V 15 Vbat
Lx 13
SCL
SDA
1 SCL
2 SDA
Vos 16 R3
470R
GND
SFH5711 U3
Log
4
C3
100nF
R3
3 I2CADR
4 VSB
U1
R4 22k GND
NCP5021
C2
GND
12
220k
5 AMBS
C4
GND
R1 2.2mH 7 IREF
12k R2 6 IPK
NNNCCC
22k GND GND FB 9
8 14
1112
10
D1
D2
D3
D4
D5
D6
D7
D8
GND
Figure 1. Typical Large Display LED Driver
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1
UQFN16
MU SUFFIX
CASE 523AF
MARKING DIAGRAM
5021
ALYWG
G
5021
A
L
Y
W
G
= Specific Device Code
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
(Note: Microdot may be in either location)
PIN CONNECTIONS
SCL
SDA
I2CADR
VSB
NC
NC
NC
FB
(Top View)
NC = Not Connected
ORDERING INFORMATION
Device
Package
Shipping†
NCP5021MUTXG UQFN16 3000 / Tape & Reel
(Pb−Free)
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specification
Brochure, BRD8011/D.
© Semiconductor Components Industries, LLC, 2009
May, 2009 − Rev. 0
1
Publication Order Number:
NCP5021/D
1 page  
NCP5021
www.DataTSahbeleet44U..AcoNmALOG SECTION: (Typical values are referenced to Ta = +25°C, Min & Max values are referenced −40°C to +85°C ambient
temperature, unless otherwise noted), operating conditions 2.85 V < Vbat < 5.5 V, unless otherwise noted.
Pin Symbol
Rating
Min Typ Max Unit
7 IREF Reference Current @ Vref = 1144 mV (Note 6)
1.0 100 mA
6 IPK Reference Current @ Vref = 1144 mV (Note 6)
1.0 100 mA
kref Reference Current to ILED peak current ratio
250
kpk Reference Current to Inductor peak current ratio
9700
7
VREF
Reference Voltage (Note 6)
−3%
1144
+3%
mV
6 VREFK Reference Voltage (Note 6)
−10% 1144 +10% mV
9 VFB Feedback Voltage (Note 7)
425 mV
MDCY
Boost Operating Maximum Duty Cycle
92 94
%
9
ILKGM
Current Mirror Leakage Current
200 nA
FLF Low Frequency Clock derived from the internal 1.3 MHz clock
0.6 20 Hz
4
VVSD
Photo Sense Bias Supply @ Ibias = 1 mA
2.5
Vbat
V
4
RVSD
Photo Sense Bias Supply internal impedance
30 W
4 ISDUSD Photo Sense Leakage Current
100 nA
GAMB0.25 Photo Sense Internal Gain 1/4
0.25
GAMB0.50 Photo Sense Internal Gain 1/2
0.5
GAMB01 Photo Sense Internal Gain 1
1
GAMB02 Photo Sense Internal Gain 2
2
GAMB04 Photo Sense Internal Gain 4
4
5 Viph Photo Sense Input Voltage (Note 9)
1.5 V
6. The external circuit must not force the IREF or IPK pin voltage either higher or lower than the 1144 mV specified. The reference voltage applies
to both IREF and IPK pins.
7. The overall output current tolerance depends upon the accuracy of the external resistor. Using 1% or better resistor is recommended.
8. This parameter guarantees the function for production test purposes.
9. The ambient sense linearity is guaranteed when the voltage at the output of the internal amplifier is limited to 1.5 V. This voltage is equal to the
input voltage times the programmed gain. Beyond this value, the operational amplifier is in the saturation region and the linearity is no longer
guaranteed.
Table 5. DIGITAL PARAMETERS SECTION (Typical values are referenced to Ta = +25°C, Min & Max values are referenced −40°C
to +85°C ambient temperature, unless otherwise noted), operating conditions 2.85 V < Vbat < 5.5 V, unless otherwise noted. (Note 10)
Symbol
Rating
Min Typ Max Unit
FSCK
VIH
InputI2C clock frequency
Positive going Input High Voltage Threshold, SCL,
SDA signals
1.6
400
VBAT
kHz
V
VIL Negative going Input High Voltage Threshold, SCL,
SDA signals
0
0.4 V
CIN SDA Input Capacitance
VIH I2C address extension
Vbat * 0.7
VIL I2C address extension
0
10. Digital inputs undershoot < −0.30 V to ground, Digital inputs overshoot < 0.30 V to VBAT
10
15
Vbat + 0.3 V
0.3
pF
V
V
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5
5 Page 
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100
10
NCP5021
HORUS : Iout %= F(Step)
Iout %
1
0.1−0.1
10 20.1
STEP
30.2
Figure 9. Typical ILED Programming Curve
ILEDREG[0..7] I−LED PEAK CURRENT
B7 B6
step 0
0
RESET
0
0
Bits [B7:B5] : Reserved for future use
Bits [B4:B0] : ILED peak current setup
B5
0
0
B4
ILED16
0
B3
ILED8
0
B2
ILED4
0
B1
ILED2
0
B0
ILED1
0
Inductor Peak Current
The peak current flowing into the inductor during normal
application is set up by the external resistor RPCA
connected between the IPK pin and ground.
The maximum IPK current is given by the internal current
mirror ratio (multiplier − kk −) typically equal to 9700. In
other word, to get a 750 mA maximum peak current in the
inductor, the reference current shall be 750 mA/9700 =
79 mA. This current is used to calculate the resistor
connected between the IPK pin and GND: RREF = 1.144 /
79e−6 = 14.4 kW.
The concept depicted in the ILED peak current
paragraph applies as well and cares must be observed to
avoid any voltage source connection to the IPK pin.
Gradual Dimming
The purpose of that function is to gradually Increase or
Decrease the brightness of the backlight / keyboard LED
upon command from the external MCU. The function is
activated and controlled by means of the I2C protocol.
The period (either upward or downward) is equal to the
time defined for each step, multiplied by the number of
steps. The number of step is derived from the value
associated with the target current.
To operate such a function, the MCU will provide three
information:
1. The target current level (either upward or
downward)
2. The time per step
3. The Upward or Downward mode of operation
When a new gradual dimming sequence is requested, the
output current increases, according to the logarithmic
curve, from the existing start value to the end value. The
end current value is defined by the contain of the Upward
or Downward register, the width of each step is defined by
the third register, the number of step being in the 1 to 32
range ($00 to $1F). In the event of software error, the
system checks that neither the maximum output current
(25 mA), nor the zero level are forced out of their
respective bounds. Similarly, software errors shall not
force NCP5021 into an uncontrolled mode of operation.
The dimming is built with 32 steps and the time delay
encoded into the third byte of the I2C transaction.
When the gradual dimming is not requested (register
selection = $01), the output current is straightforwardly set
up to the level defined by the contain of the related register
upon acknowledge of the output current byte.
The gradual dimming sequence must be set up before a
new output current data byte is send to NCP5021. At this
point, the brightness sequence takes place when the new
data byte is acknowledged by the internal I2C decoder.
Since the six registers are loaded on independent byte flow
associated to the I2C address, any parameter of the
NCP5021 chip can be updated ahead of the next function.
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| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet NCP5021.PDF ] | |
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