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ADD5203 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADD5203
Beschreibung White LED Driver with SMBus and PWM Input
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 24 Seiten
ADD5203 Datasheet, Funktion
www.DataSheet4U.com
8-String, White LED Driver with SMBus and
PWM Input for LCD Backlight Applications
ADD5203
FEATURES
White LED driver based on inductive boost converter
Integrated 50 V MOSFET with 2.9 A peak current limit
Input voltage range: 6 V to 21 V
Maximum output adjustable up to 45 V
350 kHz to 1 MHz adjustable operating frequency
Overvoltage protection (OVP) up to typical 47.5 V
Built-in soft start for boost converter
Drives up to eight LED current strings
LED current adjustable up to 30 mA for each channel
Headroom control to maximize efficiency
Adjustable dimming frequency: 200 Hz to 10 kHz
LED open and short fault protection
Selectable dimming control interface methods
PWM input
SMBus serial input
Selectable dimming modes
Fixed delay PWM dimming control with 8-bit resolution
No delay PWM dimming control with 8-bit resolution
Direct PWM dimming control
DC current dimming control with 8-bit resolution
General
Thermal shutdown
Undervoltage lockout
28-lead, 4 mm × 4 mm × 0.75 mm LFCSP_WQ
APPLICATIONS
Notebook PCs, UMPCs, and monitor displays
FUNCTIONAL BLOCK DIAGRAM
STEP-UP SWITCHING REGULATOR
EIGHT CURRENT SOURCES
PWM DUTY EXTRACTOR
8-BIT BRIGHTNESS CONTROL LOGIC
FIXED DELAY/NO DELAY DIRECT PWM/
DC CURRENT DIMMING CONTROL
WITH PWM AND/OR SMBus INTERFACE
UNDERVOLTAGE LOCKOUT
INTERNAL SOFT START
THERMAL PROTECTION
OVERVOLTAGE PROTECTION
AUTODISABLE FOR LED OPEN/SHORT
Figure 1.
GENERAL DESCRIPTION
The ADD5203 is a white LED driver for backlight applications
based on high efficiency, current-mode, step-up converter tech-
nology. It is designed with a 0.15 Ω, 2.9 A internal switch and a
pin-adjustable operating frequency between 350 kHz and 1 MHz.
The ADD5203 contains eight regulated current sources for
uniform brightness intensity. Each current source can be driven
up to 30 mA, and the LED driving current is pin adjustable by
an external resistor. The ADD5203 drives up to eight parallel
strings of multiple series connected LEDs with a ±1.5% current
matching between strings.
The ADD5203 provides various dimming modes. Each
dimming mode is selectable with an external dimming mode
selection pin. The LED dimming control interface can be
achieved through PWM input and/or SMBus. The device
provides adjustable output dimming frequency range from
200 Hz to 10 kHz by an external resistor and capacitor. The
ADD5203 operates over an input voltage range of 6 V to 21 V,
but the device can function with a voltage as low as 5.6 V.
The ADD5203 also has multiple safety protection features to
prevent damage during fault conditions. If any LED is open or
short, the device automatically disables the faulty current source.
The internal soft start prevents inrush current during startup.
Thermal shutdown protection prevents thermal damage.
The ADD5203 is available in a low profile, thermally enhanced,
4 mm × 4 mm × 0.75 mm, 28-lead, RoHS-compliant lead frame
chip scale package (LFCSP_WQ) and is specified over the
industrial temperature range of −25°C to +85°C.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2010 Analog Devices, Inc. All rights reserved.






ADD5203 Datasheet, Funktion
ADD5203
www.DataSheet4U.com
GENERAL SPECIFICATIONS
VIN = 12 V, SHDN = high, TA = −25°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.
Table 4.
Parameter
SUPPLY
Input Voltage Range
Quiescent Current
Shutdown Supply Current
VDD REGULATOR
VDD Regulated Output
PWM INPUT
PWM Voltage High
PWM Voltage Low
PWM Input Range
THERMAL SHUTDOWN
Thermal Shutdown Threshold1
Thermal Shutdown Hysteresis1
UVLO
VIN Falling Threshold
VIN Rising Threshold
SHDN CONTROL
Input Voltage High
Input Voltage Low
SHDN Pin Input Current
Symbol
VIN
IQ
ISD
VVDD_REG
VPWM_HIGH
VPWM_LOW
Test Conditions
6 V ≤ VIN ≤ 21 V, SHDN = high
6 V ≤ VIN ≤ 21 V, SHDN = low
6 V ≤ VIN ≤ 21 V
TSD
TSDHYS
VUVLOF
VUVLOR
VIH
VIL
ISHDN
VIN falling
VIN rising
SHDN = 3.3 V
Min
6
3.18
2.2
200
4.2
2.0
1 These electrical specifications are guaranteed by design.
Typ
4.2
40
3.3
160
30
4.6
5.0
6
Max
21
6.5
160
3.42
5.5
0.8
10,000
5.6
1.0
Unit
V
mA
μA
V
V
V
Hz
°C
°C
V
V
V
V
μA
Rev. 0 | Page 6 of 24

6 Page









ADD5203 pdf, datenblatt
ADD5203
www.DataSheet4U.com
PWM DIMMING MODE
The ADD5203 supports an 8-bit resolution to control brightness;
therefore, the LED dimming duty is generated with 256 steps through
the PWM input duty value in the range of 0% to 100%. In addition,
if the PWM input duty cycle is 0% longer than 10 ms, the
ADD5203 is disabled.
Note that the ADD5203 has immunity when the PWM input
duty cycle is converted to 256 steps. Even the PWM input has
±0.195% jitter.
Fixed Delay PWM Dimming
Fixed delay PWM mode is selected when SEL1 is open and SEL2 is
high for a PWM application, or when SEL1 is high and SEL2 is high
for an SMBus application. In this mode, each current source has a
fixed turn-on time delay between adjacent strings. The fixed delay
time is set by the FPWM frequency. Each channel delay time is set by
the following equation:
tD
=
2 × t FPWM
256
where tFPWM = 1/fPWM, and fPWM is the LED dimming frequency.
DUTY = 60%
PWMI
fPWM
tFPWM
(DUTY = 60%)
tOFF
tON
ILED1
tD
ILED2
ILED8
7 × tD
Figure 15. Fixed-Delay PWM Dimming Timing
No Delay PWM Dimming
No-delay PWM mode is selected when SEL1 is open and SEL2 is low
for a PWM application or when SEL1 is high and SEL2 is low for an
SMBus application. In this mode, each current source turns on and
off at the same time without any phase delay.
DUTY = 60%
PWMI
DUTY = 60%
fPWM
ILED1
tON tOFF
ILED2
ILED8
Figure 16. No Delay PWM Dimming Timing
Direct PWM Dimming
Direct PWM mode is selected when SEL1 is low and SEL2 is low
for a PWM application. In this mode, the PWM input controls
the ADD5203 LED dimming logic. It turns the current sources on
and off without any duty extraction. In addition, each current
source has no phase delay in this mode. The LED brightness is
changed by the PWM input duty ratio.
PWMI
DUTY = 60%
ILED1
DUTY = 60%
ILED2
ILED3
ILED8
Figure 17. Direct PWM Dimming Timing
DC Current Dimming
DC current mode is selected when SEL1 is low and SEL2 is open
for a PWM application, or when SEL1 is low and SEL2 is high for
an SMBus application. In this mode, the maximum LED current
is set by the value of RSET. Once the maximum LED current is set,
the LED current can be changed with 256 steps through PWM
input or SMBus.
PWMI
DUTY = 80%
DUTY = 60%
DUTY = 40%
DUTY = 20%
ILED MAX
ILED
0.8 × ILED MAX
0A
0.6 × ILED MAX
0.4 × ILED MAX
0.2 × ILED MAX
Figure 18. DC Current Dimming Timing
SAFETY FEATURES
The ADD5203 contains several safety features to provide stable
operation.
Soft Start
The ADD5203 contains an internal soft start function to reduce
inrush current at startup. The soft start time is typically 1.5 ms.
Overvoltage Protection (OVP)
The ADD5203 contains OVP circuits to prevent boost converter
damage if the output voltage becomes excessive for any reason. To
keep a safe output level, the integrated OVP circuit monitors the
output voltage. When the OVP pin voltage is reached by the OVP
rising threshold, the boost converter stops switching, causing the
output voltage to drop. When the OVP pin voltage goes lower than
the OVP falling threshold, the boot converter begins switching,
causing the output to rise. There is about 7.5% hysteresis between
the rising and falling thresholds. The OVP level can be calculated
with the following equation:
Rev. 0 | Page 12 of 24

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