TI C2012X5R1H105

LM3697
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SNOSCS2A – NOVEMBER 2013 – REVISED DECEMBER 2013
High-Efficiency Three-String White LED Driver
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FEATURES
DESCRIPTION
•
The LM3697 is a high-efficiency three string power
source for backlight or keypad LEDs in smart-phone
handsets. The high-voltage inductive boost converter
provides the power for three series LED strings for
display backlight and keypad functions (HVLED1,
HVLED2 and HVLED3).
1
•
•
•
•
•
•
•
•
Drives Three Parallel High-Voltage LED Strings
for Display and Keypad Lighting
High-Voltage Strings Capable of up to 40V
Output Voltage and up to 90% Efficiency
Up to 30 mA per Current Sink
11-Bit Configurable Dimming Resolution
PWM Input for Content Adjustable Brightness
Control (CABC)
Fully Configurable LED Grouping and Control
Four Configurable Over-Voltage Protection
Thresholds (16V, 24V, 32V, and 40V)
Selectable 500 kHz and 1MHz Switching
Frequency
30 mm2 Total Solution Size
An additional feature is a Pulse Width Modulation
(PWM) control input for content adjustable backlight
control, which can be used to control any highvoltage current sink.
The LM3697 is fully configurable via an I2Ccompatible interface. The device is available in a 12bump (1.26 mm ± 30 µm x 1.61 mm ± 30 µm x 0.6
mm ± 75 um) DSBGA and operates over a 2.7V to
5.5V input voltage range and a −40°C to +85°C
temperature range.
APPLICATIONS
•
•
Power Source for Smart Phone Illumination
Display, Keypad and Indicator Illumination
Typical Application Circuit
L
D1
VOUT up to 40V
VIN = 2.7V to 5.5V
CIN
VIN
COUT
IN
SCL
HWEN
PWM
LM3697
SDA
SW
OVP
HVLED1
HVLED2
HVLED3
PGND
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2013, Texas Instruments Incorporated
LM3697
SNOSCS2A – NOVEMBER 2013 – REVISED DECEMBER 2013
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Application Circuit Component List
Current/Voltage Rating
(Resistance)
Component
Manufacturer
Value
Part Number
Size (mm)
L
TDK
10 µH
VLF302512MT-100M
2.5 mm x 3.0 mm x 1.2
mm
620 mA/0.25Ω
COUT
TDK
1 µF
C2012X5R1H105
0805
50V
CIN
TDK
2.2 µF
C1005X5R1A225
0402
10V
Diode
On-Semi
Schottky
NSR0240V2T1G
SOD-523
40V, 250 mA
Connection Diagram
Top View
3
2
1
ABCD
Bottom View
3
2
1
DCBA
Figure 1. 12-Bump DSBGA Package YFQ0012CAA
Pin Descriptions/Functions
Pin
Name
Description
A1
PWM
PWM Brightness Control Input for CABC operation. PWM is a high-impedance input and
cannot be left floating, if not used connect to GND.
A2
SDA
Serial Data Connection for I2C-Compatible Interface.
A3
HWEN
B1
HVLED1
B2
SCL
B3
IN
Input Voltage Connection. Bypass IN to GND with a minimum 2.2 µF ceramic capacitor.
C1
HVLED2
Input Terminal to high-voltage Current Sink #2 (40V max). The boost converter regulates
the minimum of HVLED1, HVLED2 and HVLED3 to VHR.
C2
GND
Ground
C3
GND
Ground
D1
HVLED3
Input Terminal to high-voltage Current Sink #3 (40V max). The boost converter regulates
the minimum of HVLED1, HVLED2 and HVLED3 to VHR.
D2
OVP
Over-Voltage Sense Input. Connect OVP to the positive terminal of the inductive boost's
output capacitor (COUT).
D3
SW
Drain Connection for the internal NFET. Connect SW to the junction of the inductor and the
Schottky diode anode.
Hardware enable input. Drive this pin high to enable the device. Drive this pin low to force
the device into a low power shutdown. HWEN is a high-impedance input and cannot be left
floating.
Input Terminal to high-voltage Current Sink #1 (40V max). The boost converter regulates
the minimum of HVLED1, HVLED2 and HVLED3 to VHR.
Serial Clock Connection for I2C-Compatible Interface.
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
2
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SNOSCS2A – NOVEMBER 2013 – REVISED DECEMBER 2013
ABSOLUTE MAXIMUM RATINGS
(1) (2)
−0.3V to +6V
VIN to GND
−0.3V to +45V
VSW, VOVP, VHVLED1, VHVLED2, VHVLED3 to GND
VSCL, VSDA, VPWM to GND
−0.3V to +6V
VHWEN to GND
−0.3V to +6V
Continuous Power Dissipation
Internally Limited
Junction Temperature (TJ-MAX)
+150°C
− 65°C to +150°C
Storage Temperature Range
(3)
Maximum Lead Temperature (Soldering)
ESD Rating
Human Body Model (4)
Charged Device Model (5)
(1)
(2)
(3)
(4)
(5)
2.0kV
1500 V
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltages are with respect to the potential at the GND pin.
For detailed soldering specifications and information, please refer to Texas Instruments Application Note 1112: DSBGA Wafer Level
Chip Scale Package (SNVA009) available at www.ti.com.
ESD Human Body Model, ESD-HBM JESD22-A114.
ESD Charged Device Model, ESD-CDM JESD22-C101.
OPERATING RATINGS
(1) (2)
VIN to GND
2.7V to 5.5V
VSW, VOVP, VHVLED1, VVHLED2, VHVLED3 to GND
Junction Temperature Range (TJ)
(1)
(2)
(3)
(4)
0V to +40V
(3) (4)
−40°C to +125°C
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltages are with respect to the potential at the GND pin.
Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=+140°C (typ.) and
disengages at TJ=+125°C (typ.).
In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may
have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP =
+125°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the
part/package in the application (θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX).
THERMAL PROPERTIES
Thermal Resistance Junction to Ambient (θJA) (1)
(1)
55.3°C/W
Junction-to-ambient thermal resistance (θJA) is taken from a thermal modeling result, performed under the conditions and guidelines set
forth in the JEDEC standard JESD51-7. The test board is a 4-layer FR-4 board measuring 102 mm x 76 mm x 1.6 mm with a 2 x 1 array
of thermal vias. The ground plane on the board is 50 mm x 50 mm. Thickness of copper layers are 36 µm/18 µm/18 µm/36 µm (1.5
oz/1oz/1oz/1.5 oz). Ambient temperature in simulation is 22°C in still air. Power dissipation is 1W. The value of θJA of this product in the
DSBGA package could fall in a range as wide as 60°C/W to 110°C/W (if not wider), depending on PCB material, layout, and
environmental conditions. In applications where high maximum power dissipation exists special care must be paid to thermal dissipation
issues.
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ELECTRICAL CHARACTERISTICS
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(1) (2)
Limits in standard type face are for TA = +25°C and those in boldface type apply over the full operating ambient temperature
range (−40°C ≤ TA ≤ +85°C). Unless otherwise specified VIN = 3.6V.
Symbol
Parameter
Conditions
ISHDN
Shutdown Current
2.7V ≤ VIN ≤ 5.5V, HWEN = GND
ILED_MIN
Minimum LED Current
Full-Scale Current = 20.2 mA
Exponential Mapping
TSD
Min
Typ
Max
Units
1
3.0
µA
6.0
Thermal Shutdown
140
Hysteresis
15
µA
°C
Boost Converter
IHVLED(1/2/3)
IMATCH_HV
Output Current Regulation
(HVLED1, HVLED2, HVLED3)
HVLED1 to HVLED2 or HVLED3
Matching (3)
2.7V ≤ VIN ≤ 5.5V, Full-Scale Current = 20.2
mA, Brightness Code = 0xFF
2.7V ≤ VIN ≤ 5.5V
18.38
20.2
−2.5
2.5
%
Control Bank A,
Exponential Mapping,
Autoheadroom Off, PWM
Off, ILED = 500 µA
-8.5
8.5
%
Regulated Current Sink
Headroom Voltage
Auto-headroom off
400
VHR_HV
Minimum Current Sink Headroom
Voltage for HVLED Current Sinks
ILED = 95% of nominal, Full-Scale Current =
20.2 mA
190
RDSON
NMOS Switch On Resistance
ISW = 500 mA
ICL_BOOST
NMOS Switch Current Limit
VIN = 3.6V
VOVP
Output Over-Voltage Protection
ON Threshold, 2.7V ≤ VIN ≤ 5.5V
OVP select bits = 11
DMAX
2.7V ≤ VIN ≤ 5.5V
mV
275
mV
mA
Ω
0.3
880
1000
1120
38.75
40
41.1
Hysteresis
Switching Frequency
mA
Control Bank A,
Exponential Mapping,
Autoheadroom Off, PWM
Off, ILED = 20.2 mA
VREG_CS
fSW
22.02
V
1
Boost Frequency Select
Bit = 0
450
500
550
Boost Frequency Select
Bit = 1
900
1000
1100
kHz
Maximum Duty Cycle
94
%
HWEN Input
VHWEN
Logic Thresholds
Logic Low
0
0.4
Logic High
1.2
VIN
V
PWM Input
VPWM_L
Input Logic Low
2.7V ≤ VIN ≤ 5.5V
0
400
VPWM_H
Input Logic High
2.7V ≤ VIN ≤ 5.5V
1.31
VIN
V
tPWM
Minimum PWM input pulse
2.7V ≤ VIN ≤ 5.5V
0.75
µs
PWM Zero Detect enabled
mV
I2C-Compatible Voltage Specifications (SCL, SDA)
VIL
Input Logic Low
2.7V ≤ VIN ≤ 5.5V
0
400
mV
VIH
Input Logic High
2.7V ≤ VIN ≤ 5.5V
1.29
VIN
V
VOL
Output Logic Low (SDA)
ILOAD = 3 mA
400
mV
I2C-Compatible Timing Specifications (SCL, SDA)
(4)
, (see Figure 2)
t1
SCL (Clock Period)
2.5
µs
t2
Data In Setup Time to SCL High
100
ns
t3
Data Out Stable After SCL Low
0
ns
(1)
(2)
(3)
(4)
4
All voltages are with respect to the potential at the GND pin.
Min and Max limits are verified by design, test, or statistical analysis. Typical (Typ) numbers are not verified, but do represent the most
likely norm. Unless otherwise specified, conditions for typical specifications are: VIN = 3.6V and TA = +25°C.
LED current sink matching in the high-voltage current sinks (HVLED1 through HVLED3) is given as the maximum matching value
between any two current sinks, where the matching between any two high voltage current sinks (X and Y) is given as (IHVLEDX ( or
IHVLEDY) - IAVE(X-Y))/(IAVE(X-Y)) x 100. In this test all three HVLED current sinks are assigned to Bank A.
SCL and SDA must be glitch-free in order for proper brightness control to be realized.
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ELECTRICAL CHARACTERISTICS
(1) (2)
(continued)
Limits in standard type face are for TA = +25°C and those in boldface type apply over the full operating ambient temperature
range (−40°C ≤ TA ≤ +85°C). Unless otherwise specified VIN = 3.6V.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
t4
SDA Low Setup Time to SCL Low
(Start)
100
ns
t5
SDA High Hold Time After SCL
High (Stop)
100
ns
Internal POR Threshold and HWEN Timing Specification
VPOR
POR Reset Release Voltage
Threshold
VIN = 3.6V
VIN ramp time = 100 µs
2.7V ≤ VIN ≤ 5.5V
POR Reset complete
1.7
1.9
2.1
V
5
20
µs
2
tHWEN
First I C Start Pulse after HWEN
High
t1
SCL
t5
t4
SDA_IN
t2
SDA_OUT
t3
Figure 2. I2C-Compatible Interface Timing
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TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, LEDs are WLEDs part # SML-312WBCW(A), Typical Application Circuit with L = TDK (VLF302512, 4.7 µH, 10 µH,
22 µH where specified), Schottky = On-Semi (NSR0240V2T1G), TA = +25°C unless otherwise specified. Efficiency is given as
VOUT × (IHVLED1 + IHVLED2 + IHVLED3)/(VIN × IIN), matching curves are given as (ΔILED_MAX/ILED_AVE).
Top to Bottom: 3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
Three String, L=22µH, 500kHz
0.92
Three String, L=22µH, 1MHz
0.92
0.9
0.9
0.88
0.88
0.86
0.86
EFFICIENCY (%)
EFFICIENCY (%)
Top to Bottom: 3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
0.84
0.82
0.8
0.78
0.76
0.84
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
VIN (V)
4
4.5
5
C002
C002
Figure 3. LED Efficiency vs VIN, 20.2 mA/String
Figure 4. LED Efficiency vs VIN, 20.2 mA/String
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Two String, L=22µH, 500kHz
Two String, L=22µH, 1MHz
0.92
0.9
0.9
0.88
0.88
0.86
0.86
EFFICIENCY (%)
EFFICIENCY (%)
0.92
0.84
0.82
0.8
0.78
0.76
0.84
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
2.5
3
3.5
4
4.5
5
2.5
5.5
3
3.5
VIN (V)
4
4.5
5
5.5
VIN (V)
C002
C002
Figure 5. LED Efficiency vs VIN, 20.2 mA/String
Figure 6. LED Efficiency vs VIN, 20.2 mA/String
Top to Bottom:1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Top to Bottom:1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
One String, L=22µH, 500kHz
One String, L=22µH, 1MHz
0.92
0.9
0.9
0.88
0.88
0.86
0.86
EFFICIENCY (%)
EFFICIENCY (%)
0.92
0.84
0.82
0.8
0.78
0.76
0.84
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
2.5
3
3.5
4
4.5
5
5.5
2.5
VIN (V)
3
3.5
4
4.5
5
5.5
VIN (V)
C002
Figure 7. LED Efficiency vs VIN, 20.2 mA/String
6
5.5
VIN (V)
C002
Figure 8. LED Efficiency vs VIN, 20.2 mA/String
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SNOSCS2A – NOVEMBER 2013 – REVISED DECEMBER 2013
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.6V, LEDs are WLEDs part # SML-312WBCW(A), Typical Application Circuit with L = TDK (VLF302512, 4.7 µH, 10 µH,
22 µH where specified), Schottky = On-Semi (NSR0240V2T1G), TA = +25°C unless otherwise specified. Efficiency is given as
VOUT × (IHVLED1 + IHVLED2 + IHVLED3)/(VIN × IIN), matching curves are given as (ΔILED_MAX/ILED_AVE).
Top to Bottom: 3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
Three String, L=10µH, 500kHz
0.9
Three String, L=10µH, 1MHz
0.9
0.88
0.88
0.86
0.86
0.84
0.84
EFFICIENCY (%)
EFFICIENCY (%)
Top to Bottom: 3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
2.5
2.5
3
3.5
4
4.5
5
3
3.5
5.5
4
4.5
5
5.5
VIN (V)
VIN (V)
C002
C002
Figure 9. LED Efficiency vs VIN, 20.2 mA/String
Figure 10. LED Efficiency vs VIN, 20.2 mA/String
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Two String, L=10µH, 500kHz
Two String, L=10µH, 1MHz
0.9
0.88
0.88
0.86
0.86
0.84
0.84
EFFICIENCY (%)
EFFICIENCY (%)
0.9
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
VIN (V)
4
4.5
5
5.5
VIN (V)
C002
C002
Figure 11. LED Efficiency vs VIN, 20.2 mA/String
Figure 12. LED Efficiency vs VIN, 20.2 mA/String
Top to Bottom:1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Top to Bottom:1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
One String, L=10µH, 500kHz
One String, L=10µH, 1MHz
0.92
0.9
0.9
0.88
0.88
0.86
0.86
EFFICIENCY (%)
EFFICIENCY (%)
0.92
0.84
0.82
0.8
0.78
0.76
0.84
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
2.5
3
3.5
4
4.5
5
5.5
2.5
VIN (V)
3
3.5
4
4.5
5
5.5
VIN (V)
C002
Figure 13. LED Efficiency vs VIN, 20.2 mA/String
C002
Figure 14. LED Efficiency vs VIN, 20.2 mA/String
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.6V, LEDs are WLEDs part # SML-312WBCW(A), Typical Application Circuit with L = TDK (VLF302512, 4.7 µH, 10 µH,
22 µH where specified), Schottky = On-Semi (NSR0240V2T1G), TA = +25°C unless otherwise specified. Efficiency is given as
VOUT × (IHVLED1 + IHVLED2 + IHVLED3)/(VIN × IIN), matching curves are given as (ΔILED_MAX/ILED_AVE).
Top to Bottom: 3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
Three String, L=4.7µH, 500kHz
0.9
Three String, L=4.7µH, 1MHz
0.9
0.88
0.88
0.86
0.86
0.84
0.84
EFFICIENCY (%)
EFFICIENCY (%)
Top to Bottom:3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
VIN (V)
4
4.5
5
5.5
VIN (V)
C002
C002
Figure 15. LED Efficiency vs VIN, 20.2 mA/String
Figure 16. LED Efficiency vs VIN, 20.2 mA/String
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Two String, L=4.7µH, 500kHz
Two String, L=4.7µH, 1MHz
0.88
0.86
0.86
0.84
0.84
EFFICIENCY (%)
EFFICIENCY (%)
0.88
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
VIN (V)
4
4.5
5
5.5
VIN (V)
C002
C002
Figure 17. LED Efficiency vs VIN, 20.2 mA/String
Figure 18. LED Efficiency vs VIN, 20.2 mA/String
Top to Bottom:1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
Top to Bottom:1x3, 1x4, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10 (LEDs)
One String, L=4.7µH, 500kHz
One String, L=4.7µH, 1MHz
0.88
0.86
0.86
0.84
0.84
EFFICIENCY (%)
EFFICIENCY (%)
0.88
0.82
0.8
0.78
0.76
0.74
0.82
0.8
0.78
0.76
0.74
0.72
0.72
0.7
2.5
3
3.5
4
4.5
5
0.7
5.5
2.5
VIN (V)
3
3.5
4
4.5
5
5.5
VIN (V)
C002
C002
Figure 19. LED Efficiency vs VIN, 20.2 mA/String
8
Figure 20. LED Efficiency vs VIN, 20.2 mA/String
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.6V, LEDs are WLEDs part # SML-312WBCW(A), Typical Application Circuit with L = TDK (VLF302512, 4.7 µH, 10 µH,
22 µH where specified), Schottky = On-Semi (NSR0240V2T1G), TA = +25°C unless otherwise specified. Efficiency is given as
VOUT × (IHVLED1 + IHVLED2 + IHVLED3)/(VIN × IIN), matching curves are given as (ΔILED_MAX/ILED_AVE).
Top to Bottom:3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
Three String, L=22µH, 500kHz
0.9
0.88
0.88
0.86
0.86
0.84
0.84
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.00
Three String, L=22µH, 1MHz
0.9
EFFICIENCY (%)
EFFICIENCY (%)
Top to Bottom:3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
0.7
12.00
24.00
36.00
48.00
60.00
0
12
ILED (mA)
24
36
48
60
ILED (mA)
C002
C002
Figure 21. LED Efficiency vs ILED, VIN=3.6V
Figure 22. LED Efficiency vs ILED, VIN=3.6V
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Two String, L=22µH, 500kHz
Two String, L=22µH, 1MHz
0.9
0.88
0.88
0.86
0.86
0.84
0.84
EFFICIENCY (%)
EFFICIENCY (%)
0.9
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
0
12
24
36
48
0
12
ILED (mA)
24
36
48
ILED (mA)
C002
C002
Figure 23. LED Efficiency vs ILED, VIN=3.6V
Figure 24. LED Efficiency vs ILED, VIN=3.6V
Top to Bottom:3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
Top to Bottom:3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
0.88
0.88
0.86
0.86
0.84
0.84
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.00
Three String, L=10µH, 1MHz
0.9
EFFICIENCY (%)
EFFICIENCY (%)
0.9
Three String, L=10µH, 500kHz
0.7
12.00
24.00
36.00
48.00
60.00
0
ILED (mA)
12
24
36
48
60
ILED (mA)
C002
Figure 25. LED Efficiency vs ILED, VIN=3.6V
C002
Figure 26. LED Efficiency vs ILED, VIN=3.6V
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.6V, LEDs are WLEDs part # SML-312WBCW(A), Typical Application Circuit with L = TDK (VLF302512, 4.7 µH, 10 µH,
22 µH where specified), Schottky = On-Semi (NSR0240V2T1G), TA = +25°C unless otherwise specified. Efficiency is given as
VOUT × (IHVLED1 + IHVLED2 + IHVLED3)/(VIN × IIN), matching curves are given as (ΔILED_MAX/ILED_AVE).
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Two String, L=10µH, 500kHz
0.9
Two String, L=10µH, 1MHz
0.9
0.88
0.88
0.86
0.86
0.84
0.84
EFFICIENCY (%)
EFFICIENCY (%)
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.7
0
12
24
36
48
0
12
ILED (mA)
24
36
48
ILED (mA)
C002
C002
Figure 27. LED Efficiency vs ILED, VIN=3.6V
Figure 28. LED Efficiency vs ILED, VIN=3.6V
Top to Bottom:3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
Top to Bottom:3x3, 3x4, 3x5, 3x6, 3x7 (LEDs)
Three String, L=4.7µH, 500kHz
0.88
0.88
0.86
0.86
0.84
0.84
0.82
0.8
0.78
0.76
0.82
0.8
0.78
0.76
0.74
0.74
0.72
0.72
0.7
0.00
Three String, L=4.7µH, 1MHz
0.9
EFFICIENCY (%)
EFFICIENCY (%)
0.9
0.7
12.00
24.00
36.00
48.00
60.00
0
12
ILED (mA)
24
36
48
60
ILED (mA)
C002
C002
Figure 29. LED Efficiency vs ILED, VIN=3.6V
Figure 30. LED Efficiency vs ILED, VIN=3.6V
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Top to Bottom:2x3, 2x4, 2x5, 2x6, 2x7, 2x8, 2x9, 2x10 (LEDs)
Two String, L=4.7µH, 500kHz
Two String, L=4.7µH, 1MHz
0.9
0.88
0.88
0.86
0.86
0.84
0.84
EFFICIENCY (%)
EFFICIENCY (%)
0.9
0.82
0.8
0.78
0.76
0.74
0.82
0.8
0.78
0.76
0.74
0.72
0.72
0.7
0
12
24
36
0.7
48
0
ILED (mA)
12
24
36
48
ILED (mA)
C002
C002
Figure 31. LED Efficiency vs ILED, VIN=3.6V
10
Figure 32. LED Efficiency vs ILED, VIN=3.6V
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.6V, LEDs are WLEDs part # SML-312WBCW(A), Typical Application Circuit with L = TDK (VLF302512, 4.7 µH, 10 µH,
22 µH where specified), Schottky = On-Semi (NSR0240V2T1G), TA = +25°C unless otherwise specified. Efficiency is given as
VOUT × (IHVLED1 + IHVLED2 + IHVLED3)/(VIN × IIN), matching curves are given as (ΔILED_MAX/ILED_AVE).
100
7.00%
6.00%
5.00%
MATCHING (%)
CURRENT (mA)
10
1
0.1
4.00%
3.00%
2.00%
1.00%
0.00%
0.01
-1.00%
2048
1920
1792
1664
1536
1408
1280
1152
1024
896
768
640
512
384
256
128
0
2048
1920
1792
1664
1536
1408
1280
1152
1024
896
768
640
512
384
256
128
0
BRIGHTNESS CODE
BRIGHTNESS CODE
C001
Figure 33. HVLED Current vs. Brightness Code (VIN=3.6V,
Exponential Mapping)
30.0
28.0
26.0
24.0
22.0
20.0
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
7.00%
6.00%
LED CURRENT (mA)
MATCHING (%)
5.00%
4.00%
3.00%
2.00%
1.00%
0.00%
25°C
90°C
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
2048
1920
1792
1664
1536
1408
1280
1152
1024
896
768
640
512
384
256
128
0
BRIGHTNESS CODE
-40°C
0.00
-1.00%
VHR (V)
C001
Figure 35. HVLED Matching vs. Code (VIN=3.6V, Linear
Mapping)
C001
Figure 34. HVLED Matching vs. Code (VIN=3.6V,
Exponential Mapping)
C001
Figure 36. HVLED Current vs. Current Sink Headroom
Voltage
1.70
1.01
1.00
1.50
-40°C
0.99
85°C
PEAK CURRENT (A)
1.10
-40°C
0.90
25°C
0.70
25°C
0.97
0.96
85°C
0.95
0.94
0.93
0.92
0.91
0.90
5.50
5.25
5.00
4.75
4.50
4.25
VIN (V)
C001
4.00
3.75
3.50
3.25
5.50
5.25
5.00
4.75
4.50
4.25
4.00
3.75
3.50
3.25
3.00
2.75
2.50
VIN (V)
Figure 37. Shutdown Current vs. VIN and Temperature
3.00
0.50
2.75
2.50
SHUTDOWN CURRENT (uA)
0.98
1.30
C001
Figure 38. Open Loop Current Limit vs. VIN and
Temperature
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.6V, LEDs are WLEDs part # SML-312WBCW(A), Typical Application Circuit with L = TDK (VLF302512, 4.7 µH, 10 µH,
22 µH where specified), Schottky = On-Semi (NSR0240V2T1G), TA = +25°C unless otherwise specified. Efficiency is given as
VOUT × (IHVLED1 + IHVLED2 + IHVLED3)/(VIN × IIN), matching curves are given as (ΔILED_MAX/ILED_AVE).
(50% Duty Cycle, ILED FULL_SCALE = 20.2mA)
100.00%
RIPPLE CURRENT (%)
10.00%
1.00%
0.10%
0.01%
10000
8000
6000
4000
2000
0
PWM FREQUENCY (Hz)
C001
Figure 39. LED Current Ripple vs fPWM
Figure 40. Startup Response (VIN = 3.6V,2x8
LEDs,20mA/string)
D = 30% to 90%, fPWM = 10kHz, ILED_FULL SCALE = 20.2mA
(fPWM = 34kHz, ILED_FULL SCALE = 20.2mA)
25.00
20.00
LED CURRENT (mA)
MAX
15.00
10.00
TYP
5.00
MIN
0.00
100.0%
87.5%
75.0%
62.5%
50.0%
37.5%
25.0%
12.5%
0.0%
PWM DUTY CYCLE (%)
Figure 41. Response to Step Change in PWM Input Duty
Cycle
C001
Figure 42. HVLED Current vs PWM Input Duty Cycle
Typical Application Circuit, 3x6 LEDs, 20.2mA/string
Figure 43. Line Step Response
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FUNCTIONAL DESCRIPTION
The LM3697 provides the power for three high-voltage LED strings. The three high-voltage LED strings are
powered from an integrated boost converter. The device is configured over an I2C-compatible interface. The
LM3697 provides a Pulse Width Modulation (PWM) input for content adjustable brightness control.
PWM Input
The PWM input can be assigned to either of the high-voltage control banks. When assigned to a control bank,
the programmed current in the control bank becomes a function of the duty cycle (DPWM) at the PWM input and
the control bank brightness setting. When PWM is disabled DPWM is equal to one.
HWEN Input
HWEN is the global hardware enable to the LM3697. HWEN must be pulled high to enable the device. HWEN is
a high-impedance input so it cannot be left floating. When HWEN is pulled low the LM3697 is placed in
shutdown, and all the registers are reset to their default state.
Thermal Shutdown
The LM3697 contains a thermal shutdown protection. In the event the die temperature reaches +140°C, the
boost, charge pump, and current sinks will shut down until the die temperature drops to typically +125°C.
Functional Block Diagram
VOUT up to 40V
VIN = 2.7V to 5.5V
CIN
IN
SDA
SCL
I2C
Compatible
Interface
Selectable
500kHz/1MHz
Switching
Frequency
COUT
SW
Selectable Over
Voltage Protection
(16V, 24V, 32V, 40V)
OVP
Boost Converter
1A Current Limit
LED String Open/
Short Detection
High Voltage
Current Sinks
HVLED1
HVLED2
HWEN
Hardware Enable,
Reference, and
Thermal Shutdown
Backlight LED Control
1, 5 bit Full Scale
Current Select
HVLED3
2, 11 bit brightness
adjustment
3, Linear/Exponential
Dimming
4, LED Current
Ramping
PWM
Internal Low Pass
Filter
Figure 44. Functional Block Diagram
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High-Voltage LED Control
High-Voltage Boost Converter
The high-voltage boost converter provides power for the three high-voltage current sinks (HVLED1, HVLED2 and
HVLED3). The boost circuit operates using a 4.7 µH to 22 µH inductor and a 1 µF output capacitor. The
selectable 500 kHz or 1 MHz switching frequency allows for use of small external components and provides for
high boost-converter efficiency. HVLED1, HVLED2 and HVLED3 feature an adaptive current regulation scheme
where the feedback point (HVLED1, HVLED2 and HVLED3) regulates the LED headroom voltage VHR_HV. When
there are different voltage requirements in the high-voltage LED strings (string mismatch), the LM3697 will
regulate the feedback point of the highest voltage string to VHR_HV and drop the excess voltage of the lower
voltage string across the lower strings current sink.
High-Voltage Current Sinks (HVLED1, HVLED2 and HVLED3)
HVLED1, HVLED2 and HVLED3 control the current in the high-voltage LED strings as configured by Control
Bank A or B. Each Control Bank has 5-bit full-scale current programmability and 11-bit brightness control.
Assignment of the high-voltage current sinks to control bank is done through the HVLED Current Sink Output
Configuration register (see Table 5).
High-Voltage Current String Biasing
Each high-voltage current string can be powered from the LM3697’s boost output (COUT) or from an external
source. The feedback enable bits (HVLED Current Sink Feedback Enables register bits [2:0]) determine where
the high-voltage current string anodes will be connected. When set to '1' (default) the high-voltage current sink
inputs are included in the boost feedback loop. This allows the boost converter to adjust its output voltage in
order to maintain the LED headroom voltage VHR_HV at the current sink input.
When powered from alternate sources the feedback enable bits should be set to '0'. This removes the particular
current sink from the boost feedback loop. In these configurations the application must ensure that the headroom
voltage across the high-voltage current sink is high enough to prevent the current sink from going into dropout
(see the TYPICAL PERFORMANCE CHARACTERISTICS for data on the high-voltage LED current vs VHR_HV).
Setting the HVLED Current Sink Feedback Enables register bits also determines triggering of the shorted highvoltage LED String Fault flag (see Fault Flags/Protection Features section).
Boost Switching-Frequency Select
The LM3697’s boost converter has two switching frequency settings. The switching frequency setting is
controlled via the Boost Frequency Select bit (bit 0 in the Boost Control register). Operating at the 500 kHz
switching frequency results in better efficiency under lighter load conditions due to the decreased switching
losses. In this mode the inductor must be between 10 µH and 22 µH. Operating at the 1MHz switching frequency
results in better efficiency under higher load conditions resulting in lower conduction losses in the MOSFETs and
inductor. In this mode the inductor can be between 4.7 µH and 22 µH.
Automatic Switching Frequency Shift
The LM3697 has an automatic frequency select mode (bit 3 in the Boost Control register) to optimize the
frequency vs load dependent losses. In Auto-Frequency mode the boost converter switching frequency is
changed based on the high-voltage LED current. The threshold (Control A/B brightness code) at which the
frequency switch-over occurs is configurable via the Auto-Frequency Threshold register. The Auto-Frequency
Threshold register contains an 8-bit code which is compared to the 8 MSB's of the brightness code. When the
brightness code is greater than the Auto-Frequency Threshold value the boost converter switching frequency will
be 1 MHz. When the brightness code is less than or equal to the Auto-Frequency Threshold register the boost
converter switching frequency will be 500 kHz.
Figure 45 illustrates the LED efficiency improvement (3p5s LED configuration with 4.7 µH inductor) when the
Auto-Frequency feature is enabled. When the LED brightness is less than or equal to 0x6C, the switching
frequency is 500 Khz, and it improves the LED efficiency by up to 6%. When the LED brightness is greater than
0x6C, the switching frequency is 1Mhz, and it improves LED efficiency by up to 2.2%.
14
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1Mhz Eff - 500Khz Eff, 4.7uH, Three String
(Negative values when 500Khz more efficient)
3.0%
1Mhz LED Eff > 500Khz LED Eff
¨()),&,(1&<
2.0%
1.0%
0.0%
-1.0%
Auto-Frequency
Threshold = 0x6C
-2.0%
-3.0%
500Khz LED Eff > 1Mhz LED Eff
-4.0%
-5.0%
-6.0%
2048
1792
1536
1280
1024
768
512
256
0
BRIGHTNESS CODE
C002
Figure 45. Auto-Frequency LED Efficiency Improvement Illustration
Table 1 summarizes the general recommendations for Auto-Frequency Threshold setting vs Inductance values
and LED string configurations. These are general recommendations — the optimum Auto-Frequency Threshold
setting should be evaluated for each application.
Table 1. Auto-Frequency Threshold Settings
Three String
Inductor
Auto-Frequency
Two String
Peak Efficiency
Improvement
Peak
Configuration
Auto-Frequency
Threshold
Peak Efficiency
Improvement
Peak
Configuration
Threshold
4.7 µH
6C
2.20%
3p5s
AC
1.10%
2p6s
10 µH
74
1.70%
3p4s
B4
1.30%
2p5s
22 µH
7C
0.70%
3p3s
BC
0.70%
2p4s
Brightness Register Current Control
The LM3697 features Brightness Register Current Control for simple user-adjustable current control set by
writing directly to the appropriate Control Bank Brightness Registers. The current for Control Banks A & B is a
function of the full-scale LED current, the 11-bit code in the respective brightness register, and the PWM input
duty cycle (if PWM is enabled). The Control A/B brightness should always be written with LSB's first and MSB's
last. The preferred operating mode is to control the high-voltage LED brightness by setting the 3 LSB's to zero
and using only the upper 8 MSB's. In this mode the LM3697 will use the full 11-bit brightness code while ramping
the high-voltage LED brightness.
PWM Control
The LM3697's PWM input can be enabled for Control Banks A or B (see Table 14). Once enabled, the LED
current becomes a function of the code in the Control Bank Brightness Configuration Register and the PWM
input-duty cycle.
The PWM input accepts a logic level voltage and internally filters it to an analog control voltage. This results in a
linear response of duty cycle to current, where 100% duty cycle corresponds to the programmed brightness code
multiplied by the Full-Scale Current setting.
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Analog Domain
PWM Input
LPF
polarity
To Assigned
High Voltage
Current Sinks
Full-Scale
Current
Control
Digital Domain
DAC
Backlight Digital LED Control Block
Brightness Setting
Full-Scale Current Select
Exponential or Linear Mapping
Startup/Shutdown Ramp Generator
Runtime Ramp Generator
Figure 46. PWM Input Architecture
PWM Input Frequency Range
The usable input frequency range for the PWM input is governed on the low end by the cutoff frequency of the
internal low-pass filter (540 Hz, Q = 0.33) and on the high end by the propagation delays through the internal
logic. For frequencies below 2 kHz the current ripple begins to become a larger portion of the DC LED current.
Additionally, at lower PWM frequencies the boost output voltage ripple increases, causing a non-linear response
from the PWM duty cycle to the average LED current due to the response time of the boost. For the best
response of current vs. duty cycle, the PWM input frequency should be kept between 2 kHz and 100 kHz.
PWM Input Polarity
The PWM Input can be set for active low polarity, where the LED current is a function of the negative duty cycle.
This is set via the PWM Configuration register (see Table 14).
PWM Zero Detection
The LM3697 incorporates a feature to detect when the PWM input is near zero. After the near zero pulse width
has been detected the PWM pulse must be greater than tPWM to affect the HVLED output current (see
ELECTRICAL CHARACTERISTICS (1) (2)). Bit 3 in the PWM Configuration register is used to disable this feature.
Startup/Shutdown Ramp
The high-voltage LED startup and shutdown ramp times are independently configurable in the Startup/Shutdown
Transition Time Register (see Table 6). There are 16 different Startup and 16 different Shutdown times. The
startup times can be programmed independently from the shutdown times, but each Control bank is not
independently configurable.
The startup ramp time is from when the Control Bank is enabled to when the LED current reaches its initial set
point. The shutdown ramp time is from when the Control Bank is disabled to when the LED current reaches 0.
Run-Time Ramp
Current ramping from one brightness level to the next is programmed via the Run-Time Transition Time Register
(see Table 7). There are 16 different ramp-up times and 16 different ramp-down times. The ramp-up time can be
programmed independently from the ramp-down time, but each Control Bank cannot be independently
programmed. For example, programming a ramp-up or ramp-down time is a global setting for all high-voltage
LED Control Banks.
(1)
(2)
16
All voltages are with respect to the potential at the GND pin.
Min and Max limits are verified by design, test, or statistical analysis. Typical (Typ) numbers are not verified, but do represent the most
likely norm. Unless otherwise specified, conditions for typical specifications are: VIN = 3.6V and TA = +25°C.
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High-Voltage Control A/B Ramp Select
The LM3697 provides three options for Control A/B ramp times. When the Run-time Ramp Select bits are set to
00 the control bank will use both the Startup/Shutdown and Run-time ramp times. When the Run-time Ramp
Select bits are set to 01 the control bank will use the Startup/Shutdown ramp times for both startup/shutdown
and run-time. When the Run-time Ramp Select bits are set to 1x the control bank will use a zero usec Run-time
ramp.
LED Current Mapping Modes
All control banks can be programmed for either exponential or linear mapping modes (see Figure 47). These
modes determine the transfer characteristic of backlight code to LED current. Independent mapping of Control
Banks A and B is not allowed, both banks will use the same mapping mode.
Exponential Mapping
In Exponential Mapping Mode the brightness code to backlight current transfer function is given by the equation:
ILED = ILED_FULLSCALE x 0.85
(44 -
Code + 1
5.8181818
)
x DPWM
(1)
Where ILED_FULLSCALE is the full-scale LED current setting (see Table 10) , Code is the 8-bit backlight code in the
Control Brightness MSB register and DPWM is the PWM Duty Cycle. In Exponential Mapping Mode the current
ramp (either up or down) appears to the human eye as a more uniform transition then the linear ramp. This is
due to the logarithmic response of the eye.
Linear Mapping
In Linear Mapping Mode the brightness code to backlight current has a linear relationship and follows the
equation:
ILED = ILED_FULLSCALE x
1 x Code x D
PWM
255
(2)
Where ILED_FULLSCALE is the full-scale LED current setting, Code is the 8-bit backlight code in the Control
Brightness MSB register and DPWM is the PWM Duty Cycle.
21
18
Linear Mapping
ILED (mA)
15
12
9
Exponential Mapping
6
3
0
0
32
64
96
128 160 192 224 256
Code (D)
Figure 47. LED Current Mapping Modes
Fault Flags/Protection Features
The LM3697 contains both an LED open and LED short fault detection. These fault detections are designed to
be used in production level testing and not normal operation. For the fault flags to operate, they must be enabled
via the LED Fault Enable Register (see Table 22). The following sections detail the proper procedure for reading
back open and short faults in the high-voltage LED strings.
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Open LED String (HVLED)
An open LED string is detected when the voltage at the input to any active high-voltage current sink has fallen
below 200 mV, and the boost output voltage has hit the OVP threshold. This test assumes that the HVLED string
that is being detected for an open is connected to the LM3697's boost output (COUT+) (see Table 20). For an
HVLED string not connected to the LM3697's boost output voltage, but connected to another voltage source, the
boost output will not trigger the OVP flag. In this case an open LED string will not be detected.
The procedure for detecting an open fault in the HVLED current sinks (provided they are connected to the boost
output voltage) is:
• Apply power to the LM3697
• Enable Open Fault (Register 0xB4, bit [0] = 1)
• Assign HVLED1, HVLED2 and HVLED3 to Bank A (Register 0x10, Bits [2:0] = (0, 0, 0)
• Set the startup ramp times to the fastest setting (Register 0x11 = 0x00)
• Set Bank A full-scale current to 20.2 mA (Register 0x17 = 0x13)
• Configure HVLED1, HVLED2 and HVLED3 for LED string anode connected to COUT (Register 0x19, bits[2:0]
= (1,1,1))
• Set Bank A brightness to max (Register 0x21 = 0xFF)
• Enable Bank A (Register 0x24 Bit[0] = 1
• Wait 4 ms
• Read back bits[2:0] of register 0xB0. Bit [0] = 1 (HVLED1 open). Bit [1] = 1 (HVLED2 open). Bit [2] = 1
(HVLED3 open)
• Disable all banks (Register 0x24 = 0x00)
Shorted LED String (HVLED)
The LM3697 features an LED short fault flag indicating one or more of the HVLED strings have experienced a
short. The method for detecting a shorted HVLED strings is if the current sink is enabled and the string voltage
(VOUT - VHVLED1/2/3) falls to below (VIN - 1V) . This test must be performed on one HVLED string at a time.
Performing the test with more than one current sink enabled can result in a faulty reading.
The procedure for detecting a short in an HVLED string is:
• Apply power to the LM3697
• Enable Short Fault (Register 0xB4, bit [1] = 1)
• Assign HVLED1 to Bank A (Register 0x10, Bits [2:0] = (1, 1, 0)
• Set the startup ramp times to the fastest setting (Register 0x11 = 0x00)
• Set Bank A full-scale current to 20.2 mA (Register 0x17 = 0x13)
• Enable Feedback on the HVLED Current Sinks (Register 0x19, bits[2:0] = (1,1,1))
• Set Bank A brightness to max (Register 0x21 = 0xFF)
• Enable Bank A (Register 0x24 Bit[0] = 1)
• Wait 4 ms
• Read back bits[0] of register 0xB2. 1 = HVLED1 short.
• Disable all banks (Register 0x24 = 0x00)
• Repeat the procedure for the HVLED2 and HVLED3 strings
Over-Voltage Protection (Inductive Boost)
The over-voltage protection threshold (OVP) on the LM3697 has 4 different configurable options (16V, 24V, 32V,
and 40V). The OVP protects the device and associated circuitry from high voltages in the event the high-voltage
LED string becomes open. During normal operation, the LM3697’s inductive boost converter will boost the output
up so as to maintain VHR at the active, high-voltage (COUT connected) current sink inputs. When a high-voltage
LED string becomes open, the feedback mechanism is broken, and the boost converter will over-boost the
output. When the output voltage reaches the OVP threshold the boost converter will stop switching, thus allowing
the output node to discharge. When the output discharges to VOVP – 1V the boost converter will begin switching
again. The OVP sense is at the OVP pin, so this pin must be connected directly to the inductive boost output
capacitor’s positive terminal.
18
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For high-voltage current sinks that have the HVLED Current Sink Feedback Enable setting such that the highvoltage current sinks anodes are not connected to COUT (feedback is disabled), the over-voltage sense
mechanism is not in place to protect the input to the high-voltage current sink. In this situation the application
must ensure that the voltage at HVLED1, HVLED2 or HVLED3 doesn’t exceed 40V.
The default setting for OVP is set at 16V. For applications that require higher than 16V at the boost output, the
OVP threshold must be programmed to a higher level after powerup.
Current Limit (Inductive Boost)
The NMOS switch current limit for the LM3697’s inductive boost is set at 1A. When the current through the
LM3697’s NFET switch hits this over-current protection threshold (OCP), the device turns the NFET off and the
inductor’s energy is discharged into the output capacitor. Switching is then resumed at the next cycle. The
current limit protection circuitry can operate continuously each switching cycle. The result is that during highoutput power conditions the device can continuously run in current limit. Under these conditions the LM3697’s
inductive boost converter stops regulating the headroom voltage across the high-voltage current sinks. This
results in a drop in the LED current.
I2C-Compatible Interface
Start And Stop Conditions
The LM3697 is controlled via an I2C-compatible interface. START and STOP conditions classify the beginning
and the end of the I2C session. A START condition is defined as SDA transitioning from HIGH to LOW while SCL
is HIGH. A STOP condition is defined as SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C
master always generates START and STOP conditions. The I2C bus is considered busy after a START condition
and free after a STOP condition. During data transmission the I2C master can generate repeated START
conditions. A START and a repeated START condition are equivalent function-wise. The data on SDA must be
stable during the HIGH period of the clock signal (SCL). In other words, the state of SDA can only be changed
when SCL is LOW.
SDA
SCL
S
P
Start Condition
Stop Condition
Figure 48. Start and Stop Sequences
I2C-Compatible Address
The chip address for the LM3697 is 0110110 (36h). After the START condition, the I2C master sends the 7-bit
chip address followed by an eighth read or write bit (R/W). R/W= 0 indicates a WRITE and R/W = 1 indicates a
READ. The second byte following the chip address selects the register address to which the data will be written.
The third byte contains the data for the selected register.
Transferring Data
Every byte on the SDA line must be eight bits long, with the most significant bit (MSB) transferred first. Each byte
of data must be followed by an acknowledge bit (ACK). The acknowledge related clock pulse (9th clock pulse) is
generated by the master. The master releases SDA (HIGH) during the 9th clock pulse. The LM3697 pulls down
SDA during the 9th clock pulse signifying an acknowledge. An acknowledge is generated after each byte has
been received.
Table 2 lists the available registers within the LM3697.
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LM3697 Register Descriptions
Table 2. LM3697 Register Descriptions
Address
Power On Reset
Operation
Revision
Name
0x00
0x00
Dynamic
Software Reset
0x01
0x00
Dynamic
HVLED Current Sink Output Configuration
0x10
0x06
Static
Control A Startup/Shutdown Ramp Time
0x11
0x00
Static
Control B Startup/Shutdown Ramp Time
0x12
0x00
Static
Control A/B Runtime Ramp Time
0x13
0x00
Static
Control A/B Runtime Ramp Configuration
0x14
0x00
Static
Reserved
0x15
0x33
Static
Brightness Configuration
0x16
0x00
Static
Control A Full Scale Current Setting
0x17
0x13
Static
Control B Full Scale Current Setting
0x18
0x13
Static
HVLED Current Sink Feedback Enables
0x19
0x07
Static
Boost Control
0x1A
0x00
Static
Auto-Frequency Threshold
0x1B
0xCF
Static
PWM Configuration
0x1C
0x0C
Dynamic (1)
Control A Brightness LSB
0x20
0x00
Dynamic
Control A Brightness MSB
0x21
0x00
Dynamic
Control B Brightness LSB
0x22
0x00
Dynamic
Control B Brightness MSB
0x23
0x00
Dynamic
Control Bank Enables
0x24
0x00
Dynamic
HVLED Open Faults
0xB0
0x00
Production Test Only
HVLED Short Faults
0xB2
0x00
Production Test Only
LED Fault Enables
0xB4
0x00
Production Test Only
(1)
The PWM input should always be in the inactive state when setting the Control bank PWM Enable bit. The PWM configuration bits
should only be changed when the PWM is disabled for both Control Banks.
Table 3. Revision (Address 0x00)
Bits [7:4]
Not Used
Bits [3:0]
Silicon Revision
Reserved
0000 = Rev. A Silicon
Table 4. Software Reset (Address 0x01)
Bits [7:1]
Not Used
Bit [0]
Silicon Revision
0 = Normal Operation
1 = Software Reset (self-clearing)
Reserved
Table 5. HVLED Current Sink Output Configuration (Address 0x10)
Bits [7:3]
Not Used
Reserved
20
Bit [2]
HVLED3 Configuration
0 = Control A
1 = Control B (default)
Bit [1]
HVLED2 Configuration
0 = Control A
1 = Control B (default)
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Bit [0]
HVLED1 Configuration
0 = Control A (default)
1 = Control B
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Table 6. Control A & B Startup/Shutdown Ramp Time (Address 0x11 and 0x12)
Bits [7:4]
Startup Ramp
Bits [3:0]
Shutdown Ramp
0000 = 2048µs (default)
0001 = 262ms
0010 = 524ms
0011 = 1.049s
0100 = 2.09s
0101 = 4.194 s
0110 = 8.389s
0111 = 16.78s
1000 = 33.55s
1001 = 41.94s
1010 = 50.33s
1011 = 58.72s
1100 = 67.11s
1101 = 83.88s
1110 = 100.66s
1111 = 117.44s
0000 = 2048µs (default)
0001 = 262ms
0010 = 524ms
0011 = 1.049s
0100 = 2.097s
0101 = 4.194s
0110 = 8.389s
0111 = 16.78s
1000 = 33.55s
1001 = 41.94s
1010 = 50.33s
1011 = 58.72s
1100 = 67.11s
1101 = 83.88s
1110 = 100.66s
1111 = 117.44s
Table 7. Control A & B Run-Time Ramp Time (Address 0x13)
Bits [7:4]
Transition Time Ramp Up
000 = 2048µs (default)
001 = 262ms
010 = 524ms
011 = 1.049s
100 = 2.097s
101 = 4.194s
110 = 8.389s
111 = 16.78s
1000 = 33.55s
1001 = 41.94s
1010 = 50.33s
1011 = 58.72s
1100 = 67.11s
1101 = 83.88s
1110 = 100.66s
1111 = 117.44s
Bits [3:0]
Transition Time Ramp Down
000 = 2048µs (default)
001 = 262ms
010 = 524ms
011 = 1.049s
100 = 2.097s
101 = 4.194s
110 = 8.389s
111 = 16.78s
1000 = 33.55s
1001 = 41.94s
1010 = 50.33s
1011 = 58.72s
1100 = 67.11s
1101 = 83.88s
1110 = 100.66s
1111 = 117.44s
Table 8. Control A & B Run-Time Ramp Configuration (Address 0x14)
Bits [7:4]
Not Used
Reserved
Bits [3:2]
Control B Run-time Ramp Select
Bits [1:0]
Control A Run-time Ramp Select
00 = Control A/B Runtime Ramp Times
(default)
01 = Control B Startup/Shutdown Ramp
Times
1x = 0 us Ramp Time
00 = Control A/B Runtime Ramp Times
(default)
01 = Control A Startup/Shutdown Ramp
Times
1x = 0 us Ramp Time
Table 9. Control A/B Brightness Configuration (Address 0x16)
Bits [7:4]
Not Used
Reserved
Bit [3]
Bit [2]
Control B Dither Disable Control A Dither Disable
0 Enable (default)
1 Disable
0 Enable (default)
1 Disable
Bit [1]
Not Used
Reserved
Bit [0]
Control A/B Mapping
Mode
0 Exponential (default)
1 Linear
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Table 10. Control A-B Full-Scale Current Setting (Address 0x17 and 0x18)
Bits [7:5]
Not Used
Bits [4:0]
Control A, B Full-Scale Current Select Bits
Reserved
00000 = 5mA
10011 = 20.2mA (default)
11111 = 29.8mA
(0.8mA steps, FS = 5 + code * 0.8mA)
Table 11. HVLED Current Sink Feedback Enables (Address 0x19)
Bits [7:3]
Not Used
Reserved
Bit [2]
HVLED3 Feedback Enable
Bit [1]
HVLED2 Feedback Enable
Bit [0]
HVLED1 Feedback Enable
0 = LED anode is NOT CONNECTED
to COUT
1 = LED anode is CONNECTED to
COUT (default)
0 = LED anode is NOT CONNECTED
to COUT
1 = LED anode is CONNECTED to
COUT (default)
0 = LED anode is NOT CONNECTED
to COUT
1 = LED anode is CONNECTED to
COUT (default)
Table 12. Boost Control (Address 0x1A)
Bits [7:5]
Not Used
Reserved
Bit [4]
Auto-Headroom Enable
0 = Disable (default)
1 = Enable
Bit [3]
Auto-Frequency Enable
Bits [2:1]
Boost OVP Select
0 = Disable (default)
1 = Enable
00
01
10
11
= 16V (default)
= 24V
= 32V
= 40V
Bit [0]
Boost Frequency Select
0 = 500 kHz (default)
1 = 1MHz
Table 13. Auto-Frequency Threshold (Address 0x1B)
Bits [7:0]
Auto-Frequency Threshold (default = 11001111)
Table 14. PWM Configuration (Address 0x1C)
Bits [7:4]
Not Used
Reserved
Bit [3]
PWM Zero Detection
Enable
0 = Disable
1 = Enable (default)
Bit [2]
PWM Polarity
0 = Active Low
1 = Active High (default)
Bit [1]
Control B PWM Enable
0 = Disable (default)
1 = Enable
Bit [0]
Control A PWM Enable
0 = Disable (default)
1 = Enable
Table 15. Control A Brightness LSB (Address 0x20)
Bits [7:3]
Not Used
Bits [2:0]
Control A Brightness [2:0]
Reserved
Brightness LSB
Table 16. Control A Brightness MSB (Address 0x21)
Bits [7:0]
Control A Brightness [11:3]
Brightness MSB (Ramping starts when MSB is written)
When the Mapping Mode is set for exponential mapping (Control Bank_Brightness Configuration Register Bit [2] = 0), the current
approximates the equation:
ILED = ILED_FULLSCALE x 0.85
(44 -
Code + 1
5.8181818
)
x DPWM
(3)
When the Mapping Mode is set for linear mapping (Control Bank_Brightness Configuration Register Bit [2] = 1), the current approximates
the equation:
1
I
=I
x
x
LED
LED_ FULLSCALE 255 Code
(4)
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Table 17. Control B Brightness LSB (Address 0x22)
Bits [7:3]
Not Used
Bits [2:0]
Control B Brightness [2:0]
Reserved
Brightness LSB
Table 18. Control B Brightness MSB (Address 0x23)
Bits [7:0]
Control B Brightness [11:3]
Brightness MSB (Ramping starts when MSB is written)
When the Mapping Mode is set for exponential mapping (Control Bank_Brightness Configuration Register Bit [2] = 0), the current
approximates the equation:
ILED = ILED_FULLSCALE x 0.85
(44 -
Code + 1
5.8181818
)
x DPWM
(5)
When the Mapping Mode is set for linear mapping (Control Bank_Brightness Configuration Register Bit [2] = 1), the current approximates
the equation:
1
I
=I
x
x
LED
LED_ FULLSCALE 255 Code
(6)
Table 19. Control Bank Enables (Address 0x24)
Bit [1]
Control B
Enable
Bit [7:2]
Not Used
Reserved
0 = Disable
(default)
1 = Enable
Bit [0]
Control A
Enable
0 = Disable
(default)
1 = Enable
Table 20. HVLED Open Faults (Address 0xB0)
Bits [7:3]
Not Used
Bit [2]
HVLED3 Open
Bit [1]
HVLED2 Open
Bit [0]
HVLED1 Open
Reserved
0 = Normal Operation
1 = Open
0 = Normal Operation
1 = Open
0 = Normal Operation
1 = Open
Table 21. HVLED Short Faults (Address 0xB2)
Bits [7:3]
Not Used
Bit [2]
HVLED3 Short
Bit [1]
HVLED2 Short
Bit [0]
HVLED1 Short
Reserved
0 = Normal Operation
1 = Short
0 = Normal Operation
1 = Short
0 = Normal Operation
1 = Short
Table 22. LED Fault Enable (Address 0xB4)
Bits [7:2]
Not Used
Bit [1]
Short Faults Enable
Bit [0]
Open Faults Enable
Reserved
0 = Disable (default)
1 = Enable
0 = Disable (default)
1 = Enable
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APPLICATION INFORMATION
Boost Converter Maximum Output Power (Boost)
The LM3697's maximum output power is governed by two factors: the peak current limit (ICL = 880 mA min), and
the maximum output voltage (VOVP). When the application causes either of these limits to be reached it is
possible that the proper current regulation and matching between LED current strings will not be met.
Peak Current Limited
In the case of a peak current limited situation, when the peak of the inductor current hits the LM3697's current
limit, the NFET switch turns off for the remainder of the switching period. If this happens each switching cycle the
LM3697 will regulate the peak of the inductor current instead of the headroom across the current sinks. This can
result in the dropout of the boost output connected current sinks, and the LED current dropping below its
programmed level.
The peak current in a boost converter is dependent on the value of the inductor, total LED current in the boost
(IOUT), the boost output voltage (VOUT) (which is the highest voltage LED string + VHR ), the input voltage
(VIN), the switching frequency, and the efficiency (Output Power/Input Power). Additionally, the peak current is
different depending on whether the inductor current is continuous during the entire switching period (CCM), or
discontinuous (DCM) where it goes to 0 before the switching period ends. For Continuous Conduction Mode the
peak inductor current is given by:
IPEAK =
IOUT x VOUT
VIN x efficiency
+
VIN
2 x fSW x L
x 1-
VIN x efficiency
VOUT
(7)
For Discontinuous Conduction Mode the peak inductor current is given by:
2 u IOUT
IPEAK =
´
¶ SW
u L u efficiency
u §VOUT - VIN u efficiency·
©
¹
(8)
To determine which mode the circuit is operating in (CCM or DCM) it is necessary to perform a calculation to test
whether the inductor current ripple is less than the anticipated input current (IIN). If ΔIL is less than IIN then the
device will be operating in CCM. If ΔIL is greater than IIN then the device is operating in DCM.
IOUT u VOUT
VIN u efficiency
>
VIN
´
¶SW
uL
u §1 ©
VIN u efficiency ·
VOUT
¹
(9)
Typically at currents high enough to reach the LM3697's peak current limit, the device will be operating in CCM.
The following figures show the output current and voltage derating for a 10 µH and a 22 µH inductor. These plots
take equations (1) and (2) from above and plot VOUT and IOUT with varying VIN, a constant peak current of 880
mA (ICL_MIN), 500 kHz switching frequency, and a constant efficiency of 85%. Using these curves can give a good
design guideline on selecting the correct inductor for a given output power requirement. A 10 µH inductor will
typically be a smaller device with lower on resistance, but the peak currents will be higher. A 22 µH inductor
provides for lower peak currents but a larger sized device is required to match the DC resistance of a 10 µH
inductor.
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0.1
0.095
0.09
0.085
IOUT (A)
0.08
0.075
0.07
0.065
VOUT=22V
VOUT=24V
VOUT=26V
VOUT=30V
VOUT=34V
VOUT=38V
0.06
0.055
0.05
0.045
0.04
2.7
2.9
3.1
3.3
3.5
3.7
3.9 4.1
VIN (V)
4.3
4.5
4.7
4.9
5.1
5.3
5.5
4.9
5.1
5.3
5.5
Figure 49. Maximum Output Power (22 µH)
0.1
VOUT=22V
VOUT=24V
VOUT=26V
VOUT=30V
VOUT=34V
VOUT=38V
0.095
0.09
0.085
0.08
IOUT (A)
0.075
0.07
0.065
0.06
0.055
0.05
0.045
0.04
0.035
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
VIN (V)
Figure 50. Maximum Output Power (10 µH)
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Output Voltage Limited
In the case of an output voltage limited situation, when the boost output voltage hits the LM3697's OVP
threshold, the NFET turns off and stays off until the output voltage falls below the hysteresis level (typically 1V
below the OVP threshold). This results in the boost converter regulating the output voltage to the programmed
OVP threshold (16V, 24V, 32V, or 40V), causing the current sinks to go into dropout. The default OVP threshold
is set at 16V. For LED strings higher than typically 4 series LEDs, the OVP will have to be programmed higher
after power-up or after a HWEN reset.
Layout Guidelines and Component Selection (Boost)
The LM3697's inductive boost converter sees a high switched voltage (up to 40V) at the SW pin, and a step
current (up to 1A) through the Schottky diode and output capacitor each switching cycle. The high switching
voltage can create interference into nearby nodes due to electric field coupling (I = CdV/dt). The large step
current through the diode and the output capacitor can cause a large voltage spike at the SW pin and the OVP
pin due to parasitic inductance in the step current conducting path (V = Ldi/dt). Board layout guidelines are
geared towards minimizing this electric field coupling and conducted noise. Figure 51 highlights these two noisegenerating components.
Spike Voltage
VOUT + VF Schottky
Pulsed voltage at SW
Current through
Schottky and
COUT
IPEAK
Current
through
inductor
IAVE = IIN
Paracitic
Circuit Board
Inductances
Affected Node
due to capacitive coupling
Cp1
L
Lp1
D1
Lp2
LCD Display
Up to 40V
2.7V to 5.5V
C OUT
VLOGIC
SW
IN
10 k:
10 k:
Lp3
C IN
LM3697
SCL
OVP
SDA
HVLED1
HVLED2
HVLED3
GND
Figure 51. LM3697's Inductive Boost Converter Showing Pulsed Voltage at SW (High dV/dt) and Current
Through Schottky and COUT (High dI/dt)
The following list details the main (layout sensitive) areas of the LM3697’s inductive boost converter in order of
decreasing importance:
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1. Output Capacitor
– Schottky Cathode to COUT+
– COUT− to GND
2. Schottky Diode
– SW Pin to Schottky Anode
– Schottky Cathode to COUT+
3. Inductor
– SW Node PCB capacitance to other traces
4. Input Capacitor
– CIN+ to IN pin
Boost Output Capacitor Selection and Placement
The LM3697's inductive boost converter requires a 1 µF output capacitor. The voltage rating of the capacitor
depends on the selected OVP setting. For the 16V setting a 16V capacitor must be used. For the 24V setting a
25V capacitor must be used. For the 32V setting, a 35V capacitor must be used. For the 40V setting a 50V
capacitor must be used. Pay careful attention to the capacitor's tolerance and DC bias response. For proper
operation the degradation in capacitance due to tolerance, DC bias, and temperature, should stay above 0.4µF.
This might require placing two devices in parallel in order to maintain the required output capacitance over the
device operating range, and series LED configuration.
Because the output capacitor is in the path of the inductor current discharge path it will see a high-current step
from 0 to IPEAK each time the switch turns off and the Schottky diode turns on. Any inductance along this series
path from the cathode of the diode through COUT and back into the LM3697's GND pin will contribute to voltage
spikes (VSPIKE = LP_ × dI/dt) at SW and OUT. These spikes can potentially over-voltage the SW pin, or feed
through to GND. To avoid this, COUT+ must be connected as close as possible to the Cathode of the Schottky
diode, and COUT− must be connected as close as possible to the LM3697's GND bump. The best placement for
COUT is on the same layer as the LM3697 in order to avoid any vias that can add excessive series inductance.
Schottky Diode Placement
The Schottky diode must have a reverse breakdown voltage greater than the LM3697’s maximum output voltage
(see Over-Voltage Protection (Inductive Boost) section). Additionally, the diode must have an average current
rating high enough to handle the LM3697’s maximum output current, and at the same time the diode's peak
current rating must be high enough to handle the peak inductor current. Schottky diodes are required due to their
lower forward voltage drop (0.3V to 0.5V) and their fast recovery time.
In the LM3697’s boost circuit the Schottky diode is in the path of the inductor current discharge. As a result the
Schottky diode sees a high-current step from 0 to IPEAK each time the switch turns off and the diode turns on.
Any inductance in series with the diode will cause a voltage spike (VSPIKE = LP_ × dI/dt) at SW and OUT. This
can potentially over-voltage the SW pin, or feed through to VOUT and through the output capacitor and into
GND. Connecting the anode of the diode as close as possible to the SW pin and the cathode of the diode as
close as possible to COUT+ will reduce the inductance (LP_) and minimize these voltage spikes.
Inductor Placement
The node where the inductor connects to the LM3697’s SW bump has 2 issues. First, a large switched voltage (0
to VOUT + VF_SCHOTTKY) appears on this node every switching cycle. This switched voltage can be
capacitively coupled into nearby nodes. Second, there is a relatively large current (input current) on the traces
connecting the input supply to the inductor and connecting the inductor to the SW bump. Any resistance in this
path can cause voltage drops that can negatively affect efficiency and reduce the input operating voltage range.
To reduce the capacitive coupling of the signal on SW into nearby traces, the SW bump-to-inductor connection
must be minimized in area. This limits the PCB capacitance from SW to other traces. Additionally, highimpedance nodes that are more susceptible to electric field coupling need to be routed away from SW and not
directly adjacent or beneath. This is especially true for traces such as SCL, SDA, HWEN, and PWM. A GND
plane placed directly below SW will dramatically reduce the capacitance from SW into nearby traces.
Lastly, limit the trace resistance of the VIN-to-inductor connection and from the inductor-to-SW connection, by
use of short, wide traces.
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27
LM3697
SNOSCS2A – NOVEMBER 2013 – REVISED DECEMBER 2013
www.ti.com
Boost Input Capacitor Selection and Placement
The input capacitor on the LM3697 filters the voltage ripple due to the switching action of the inductive boost and
the capacitive charge pump doubler. A ceramic capacitor of at least 2.2 µF must be used.
For the LM3697’s boost converter, the input capacitor filters the inductor current ripple and the internal MOSFET
driver currents during turn on of the internal power switch. The driver current requirement can range from 50 mA
at 2.7V to over 200 mA at 5.5V with fast durations of approximately 10 ns to 20 ns. This will appear as high di/dt
current pulses coming from the input capacitor each time the switch turns on. Close placement of the input
capacitor to the IN pin and to the GND pin is critical since any series inductance between IN and CIN+ or CIN−
and GND can create voltage spikes that could appear on the VIN supply line and in the GND plane.
Close placement of the input bypass capacitor at the input side of the inductor is also critical. The source
impedance (inductance and resistance) from the input supply, along with the input capacitor of the LM3697, form
a series RLC circuit. If the output resistance from the source (RS) is low enough the circuit will be underdamped
and will have a resonant frequency (typically the case). Depending on the size of LS the resonant frequency
could occur below, close to, or above the LM3697's switching frequency. This can cause the supply current ripple
to be:
1. Approximately equal to the inductor current ripple when the resonant frequency occurs well above the
LM3697's switching frequency;
2. Greater than the inductor current ripple when the resonant frequency occurs near the switching frequency; or
3. Less than the inductor current ripple when the resonant frequency occurs well below the switching frequency.
Figure 52 shows the series RLC circuit formed from the output impedance of the supply and the input
capacitor.
The circuit is redrawn for the AC case where the VIN supply is replaced with a short to GND and the LM3697 +
Inductor is replaced with a current source (ΔIL). Equation 1 is the criteria for an underdamped response.
Equation 2 is the resonant frequency. Equation 3 is the approximated supply current ripple as a function of LS,
RS, and CIN.
As an example, consider a 3.6V supply with 0.1Ω of series resistance connected to CIN through 50 nH of
connecting traces. This results in an under-damped input-filter circuit with a resonant frequency of 712 kHz.
Since both the 1 MHz and 500 kHz switching frequency options lie close to the resonant frequency of the input
filter, the supply current ripple is probably larger than the inductor current ripple. In this case, using equation 3,
the supply current ripple can be approximated as 1.68 times the inductor current ripple (using a 500 kHz
switching frequency) and 0.86 times the inductor current ripple using a 1 MHz switching frequency. Increasing
the series inductance (LS) to 500 nH causes the resonant frequency to move to around 225 kHz, and the supply
current ripple to be approximately 0.25 times the inductor current ripple (500 kHz switching frequency) and 0.053
times for a 1 MHz switching frequency.
28
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LM3697
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SNOSCS2A – NOVEMBER 2013 – REVISED DECEMBER 2013
'IL
ISUPPLY
30200328
RS
LS
L
SW
+
IN
VIN Supply
LM3697
-
CIN
ISUPPLY
LS
RS
CIN
'IL
2
1.
RS
1
>
LS x CIN 4 x LS2
2. f RESONANT =
1
2S LS x CIN
3. I SUPPLYRIPP LE | 'IL x
1
2S x 500 kHz x CIN
2
·
§
1
2
¸
RS + ¨¨2S x 500 kHz x LS ¸
2
S
x
500
kHz
x
C
IN
¹
©
Figure 52. Input RLC Network
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29
LM3697
SNOSCS2A – NOVEMBER 2013 – REVISED DECEMBER 2013
www.ti.com
REVISION HISTORY
Changes from Original (November 2013) to Revision A
Page
•
Added captions to graphs ..................................................................................................................................................... 6
•
Changed condition for two-string LED Efficiency vs VIN, 20.2 mA/String graph ................................................................. 7
•
Added graph ....................................................................................................................................................................... 15
•
Added Auto-Frequency Threshold Settings table ............................................................................................................... 15
•
Added graphic ..................................................................................................................................................................... 16
30
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PACKAGE OPTION ADDENDUM
www.ti.com
5-Feb-2014
PACKAGING INFORMATION
Orderable Device
Status
(1)
LM3697YFQR
ACTIVE
Package Type Package Pins Package
Drawing
Qty
DSBGA
YFQ
12
3000
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Green (RoHS
& no Sb/Br)
SNAGCU
Level-1-260C-UNLIM
Op Temp (°C)
Device Marking
(4/5)
-40 to 125
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
5-Feb-2014
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
20-Dec-2013
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
LM3697YFQR
Package Package Pins
Type Drawing
SPQ
DSBGA
3000
YFQ
12
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
178.0
8.4
Pack Materials-Page 1
1.35
B0
(mm)
K0
(mm)
P1
(mm)
1.75
0.76
4.0
W
Pin1
(mm) Quadrant
8.0
Q1
PACKAGE MATERIALS INFORMATION
www.ti.com
20-Dec-2013
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LM3697YFQR
DSBGA
YFQ
12
3000
210.0
185.0
35.0
Pack Materials-Page 2
MECHANICAL DATA
YFQ0012xxx
D
0.600
±0.075
E
TMD12XXX (Rev B)
D: Max = 1.64 mm, Min = 1.58 mm
E: Max = 1.29 mm, Min = 1.23 mm
4215079/A
NOTES:
A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994.
B. This drawing is subject to change without notice.
www.ti.com
12/12
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