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PDF ISL97677 Data sheet ( Hoja de datos )
| Número de pieza | ISL97677 | |
| Descripción | SMBus/I2C 8-Channel LED Driver | |
| Fabricantes | Intersil Corporation | |
| Logotipo |  |
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SMBus/I2C 8-Channel LED Driver
ISL97677
The ISL97677 is an SMBus/I2C controlled multi-channel
LED driver for notebook and monitor LCD backlight
applications with PWM dimming and fault reporting
functions. The ISL97677 is capable of driving typically
96 pieces of 3.4V/50mA LEDs. The ISL97677 has
multiple channels of voltage controlled current sources
with typical currents matching to ±0.7%, which
compensate for the non-uniformity effect of forward
voltages variance in the LED strings. To minimize the
voltage headroom and power loss in the typical
multi-string operation, the ISL97677 features dynamic
headroom control that monitors the highest LED forward
voltage string and uses its feedback signal for output
regulation.
The ISL97677 can operate in multiple modes of
operations. It can be controlled by SMBus/I2C
communications and an external PWM dimming signal
with currents matching of ±1% across all ranges.
The ISL97677 features extensive protection functions
that include string open and short circuit detections, OVP,
and OTP. The fault conditions will be recorded in the
Fault/Status register. There are selectable short-circuit
thresholds and the switching frequency can be
programmed between 500kHz and 1.5MHz.
ISL97677 is available in the 32 Leads QFN 5mmx5mm
and operate from -40°C to +85°C with input voltage
ranges from 4.75V to 26V.
Features
• 8 Channels
• 4.75V ~ 26V Input
• 45V Maximum Output
• Drive Typically 96 LEDs (3.4V/50mA each)
• Dimming Controls
- SMBus/I2C 8-Bit PWM Dimming
- SMBus and External PWM DPST Dimming Control
- External PWM Dimming with or without SMBus/I2C
- PWM Dimming range from 0.4% to 100%
• Current Matching ±0.7%
• Protections
- String Open Circuit and Short Circuit Detections,
OVP, and OTP
• Adjustable Dimming Frequency
• Adjustable Switching Frequency
• 32 Ld (5mmx5mm) QFN Package
Applications
• Notebook Displays WLED or RGB LED Backlighting
• LCD Monitor LED Backlighting
www.DataSheet4U.com
November 13, 2009
FN6996.1
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2009. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
1 page  
ISL97677
Absolute Maximum Ratings
voltage ratings are all with respect to AGND pin
VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 27V
EN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 27V
VLOGIC . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.75V
VDC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 5.75V
COMP, RSET, FPWM, FSW . . . . . . . . . . . . . . . . -0.3V to min
. . . . . . . . . . . . . . . . . . . . . . . . . . . . (VDC + 0.3V, 5.75V)
SMBCLK, SMBDAT, PWM . . . . . . . . . . . . . . . -0.3V to 5.75V
CH1 - CH8, LX, OVP . . . . . . . . . . . . . . . . . . . . -0.3V to 45V
PGND, AGND . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +0.3V
Recommended Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . -40°C to +85°C
Thermal Information
Thermal Resistance (Typical)
θJA (°C/W) θJC (°C/W)
32 Ld QFN (Notes 4, 5) . . . . . . . . . 31
3
Thermal Characterization (Typical, Note 6)
PSIJT (°C/W)
32 Ld QFN . . . . . . . . . . . . . . . . . . . . . . . . . 0.2
Maximum Continuous Junction Temperature . . . . . . +125°C
Storage Temperature . . . . . . . . . . . . . . . -65°C to +150°C
Power Dissipation
TA < +25°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2W
TA < +70°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8W
TA < +85°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3W
TA < +100°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8W
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . .see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact
product reliability and result in failures not covered by warranty.
NOTES:
4. θJA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief
TB379 for details.
5. For θJC, the “case temp” location is the center of the exposed metal pad on the package underside.
6. PSIJT is the PSI junction-to-top thermal characterization parameter. If the package top temperature can be measured with
this rating then the die junction temperature can be estimated more accurately than the θJC and θJC thermal resistance
ratings.
5E. lectrical Specifications
All specifications below are characterized at TA = -40°C to +85°C; VIN = 12V, /SHUT = 5V,
ISET = 36kΩ, unless otherwise noted. Boldface limits apply over the operating
temperature range, -40°C to +85°C.
PARAMETER
DESCRIPTION
CONDITION
MIN
MAX
(Note 7) TYP (Note 7) UNIT
GENERAL
VIN Backlight Supply Voltage
4.75
26
(Note 8)
V
IVIN_SHDN
VIN Shutdown Current
VOUT
Output Voltage
www.DVaUtaVSLOheet4U.com Undervoltage Lockout Threshold
VUVLO_HYS
Undervoltage Lockout Hysteresis
LINEAR REGULATOR
/SHUT = 0
5
45
2.9 3.3
300
µA
V
V
mV
VDC
5V Analog Bias Regulator
VDC_DROP
VDC LDO Dropout Voltage
IVDC
Active Current
VLOGIC
2.5V Logic Bias Regulator
VLOGIC_DROP
VLOGIC LDO Dropout Voltage
BOOST SWITCHING REGULATOR
VIN > 6V
IVDC = 30mA
/SHUT = 5V, R = 33kΩ
VIN > 6V
IVLOGIC = 30mA
4.8
2.3
5 5.1
71 100
10
2.4 2.5
31 100
V
mV
mA
V
mV
SS Soft-Start
16 ms
SWILimit
rDS(ON)
Boost FET Current Limit
Internal Boost Switch ON-Resistance
TA = +25°C to +85°C
3.0 4.7
130
A
mΩ
5 FN6996.1
November 13, 2009
5 Page 
ISL97677
Typical Performance Curves (Continued)
VO (1V/DIV)
VO (500mV/DIV)
ILED (20mA/DIV)
ILED (20mA/DIV)
FIGURE 21. LOAD REGULATION WITH ILED CHANGES
FROM 0% TO 100% PWM DIMMING
FIGURE 22. LOAD REGULATION WITH ILED CHANGES
FROM 100% to 0% PWM DIMMING
VO (20V/DIV)
EN (5V/DIV)
IIN (1A/DIV)
ILED (50mA/DIV)
www.DataSheet4U.com
FIGURE 23. DISABLE PROFILE
Theory of Operation
PWM Boost Converter
The current mode PWM boost converter produces the
minimal voltage needed to enable the LED string with the
highest forward voltage drop to run at the programmed
current. The ISL97677 employs current mode control
boost architecture that has a fast current sense loop and
a slow voltage feedback loop. Such architecture achieves
a fast transient response that is essential for the
notebook backlight application where the power can be
several Li-ion cell batteries or instantly change to an
AC/DC adapter without rendering a noticeable visual
nuisance. The number of LEDs that can be driven by
ISL97677 depends on the type of LED chosen in the
application. The ISL97677 is capable of boosting up to
45V and drive 8 channels of LEDs at maximum of 45mA
per channel.
Current Matching and Current Accuracy
Each channel of the LED current is regulated by the
current source circuit, as shown in Figure 24.
The LED peak current is set by translating the RSET
current to the output with a scaling factor of 707.9/RSET.
The source terminals of the current source MOSFETs are
designed to run at 500mV to optimize power loss vs
accuracy requirements. The sources of errors of the
channel-to-channel current matching come from the
op amps offset, internal layout, reference, and current
source resistors. These parameters are optimized for
current matching and absolute current accuracy.
However, the absolute accuracy is additionally
determined by the external RSET. A 0.1% tolerance
resistor is recommended.
11 FN6996.1
November 13, 2009
11 Page | ||
| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet ISL97677.PDF ] | |
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