LM3565
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SNVS957 – JANUARY 2013
4MHz, High-Current Flash LED Driver
Check for Samples: LM3565
FEATURES
DESCRIPTION
•
•
•
The LM3565 is a 4 MHz fixed-frequency, current
mode synchronous boost converter designed to drive
two series flash LEDs at 930 mA. A high-voltage
current source allows the LEDs to be terminated to
the GND plane eliminating the need for an additional
return trace back to the IC.
1
•
•
•
•
•
•
•
•
High Efficiency Synchronous Boost Converter
Drives 2 LEDs in Series with up to 930 mA
External Strobe Pin for Hardware Enabled
Flash
External Torch Pin for Hardware Enabled
Torch
Dedicated Transmit Interrupt Pin
8-Bit ADC for LED Voltage and Input Voltage
Monitoring
Automatic Diode Current Scale Back
PWM Control in Flash and Assist Modes
Fault Detection and Reporting
400 kHz I2C-Compatible Interface
16-Bump, 1.990 mm x 1.990 mm x 0.6 mm
DSBGA Package (YZR0016AAA)
A dedicated Strobe pin provides a direct interface to
trigger the flash event, while an external Torch pin
provides an additional method for enabling the LEDs
in a constant current mode. The LM3565 can
adaptively scale the maximum flash level delivered to
the LEDs based upon the measured input voltage.
Multiple protection features are available on the
LM3565 ranging from over-voltage protection to
output short-circuit detection.
The LM3565 has four selectable inductor current
limits to help the user select an inductor that is
appropriate for the design.
APPLICATIONS
•
Camera Phone LED Flash
TYPICAL APPLICATION CIRCUIT
1 µH
CIN1
CIN2
10 µF
100 nF
VIN
SW
x2 V
OUT
+
VBAT
x2
-
LM3565
STROBE
COUT1
COUT2
10 µF
10 µF
VLED
x2
TORCH
ENABLE
WLED
SCL
SDA
Tx-MASK
PGND
AGND
x2
WLED
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
LM3565
SNVS957 – JANUARY 2013
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CONNECTION DIAGRAM
A1
A2
A3
A4
A4
A3
A2
A1
B1
B2
B3
B4
B4
B3
B2
B1
C1
C2
C3
C4
C4
C3
C2
C1
D1
D2
D3
D4
D4
D3
D2
D1
TOP VIEW
(BUMPS FACE DOWN)
BOTTOM VIEW
(BUMPS FACE UP)
PIN A1 LOCATION
PIN FUNCTIONS
PIN
INPUT/OUTPUT
(I/O)
DESCRIPTION
NO.
NAME
A1
PGND
A2
PGND
A3
VIN
I
Input voltage pin of the device. Connect input bypass capacitor very close to this pin.
A4
ENABLE
I
Chip Enable. High = Standby, Low = Shutdown.
B1
SW1
I
Inductor connection.
B2
SW2
I
Inductor connection.
B3
TORCH
I
Hardware Torch Enable Pin.
Power GND.
Power GND.
B4
TX-MASK
I
Hardware Transmit Interrupt Pin.
C1
VOUT1
O
Boost output. Connect output bypass capacitor very close to this pin.
C2
VOUT2
O
Boost output. Tie to VOUT1.
C3
STROBE
I
Strobe signal input pin to synchronize flash pulse in I2C-compatible mode. This signal
usually comes from the camera processor.
C4
SDA
I/O
Serial Data Pin for I2C-compatible Interface.
D1
LEDOUT1
I/O
LED Current Source Output.
D2
LEDOUT2
I/O
LED Current Source Output. Tie to LEDOUT1.
D3
AGND
D4
SCL
A/D Ground Pin.
I
Serial Clock Pin for I2C-compatible Interface.
2
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SNVS957 – JANUARY 2013
ABSOLUTE MAXIMUM RATINGS (1) (2)
If Military/Aerospace specified devices are required, contact the Texas Instruments Sales Office/ Distributors for availability
and specifications.
VALUE
MIN
VIN
–0.3
+6
V
TORCH, TX-MASK, STROBE, ENABLE, SDA, SCL
–0.3
(VIN +0.3V)
+6.0
V
+10
V
+150
°C
+150
°C
+2.5
kV
VOUT1, VOUT2, LEDOUT1, LEDOUT2, SW1, SW2
Continuous power dissipation
TJ-MAX
(3)
Internally Limited
Junction temperature
Storage temperature range
Maximum lead temperature (soldering)
–55
(4)
ESD rating, Human Body Model
(1)
(2)
(3)
(4)
UNIT
MAX
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 = 150°C (typ.) and
disengages at TJ = 115°C (typ). Thermal shutdown is specified by design.
For detailed soldering specifications and information, refer to Texas Instruments Application Note: AN-1112: DSBGA Wafer Level Chip
Scale Package for Recommended Soldering Profiles.
RECOMMENDED OPERATING CONDITIONS (1) (2)
MAX
UNIT
Input voltage range
+2.5
MIN
NOM
+5.5
V
Output voltage range
+5.5
+8.5
V
TJ
Junction temperature range
–30
+125
°C
TA
Ambient temperature range (3)
–30
+85
°C
THERMAL PROPERTIES
θJA
(1)
(2)
(3)
(4)
Thermal resistance junction-to-ambient (4)
+62.2
°C/W
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.
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).
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 2x1 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/3 µm (1.5 oz/1
oz/1 oz/1.5 oz). Ambient temperature in simulation is 22°C, still air. Power dissipation is 1.2W.
3
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ELECTRICAL CHARACTERISTICS
Limits in standard typeface are for TA = +25°C. Limits in boldface type apply over the full operating ambient temperature
range (−30°C ≤ TA ≤ 85°C). Unless otherwise specified: 2.7V ≤ VIN ≤ 4.4V. (1) (2)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
CURRENT AND VOLTAGE SPECIFICATIONS
VOUT =7.5V
VLED = 7.2V
60 mA ≤ ILED ≤
930 mA
ILED-OUT
LED Current accuracy
VCSH
Current source headroom voltage
VOVP
Over-voltage protection range
ISD
Shutdown current
ISB
Standby current
IQ
Operating quiescent current
Part switching
UVLO
Under-voltage lock out
Falling VIN
2.3
2.4
2.5
V
UVLOHYST
UVLO Hysteresis
Rising VIN
50
100
150
mV
CL Reg value = 00
2.07
2.3
2.53
CL Reg value = 01
2.34
2.6
2.86
CL Reg value = 10
2.61
2.9
3.19
CL Reg value = 11
2.97
3.3
3.63
ILIM
Trip Point (Rising)
Peak current limit
(–5%)
9.0
(+5%)
300
350
9.5
10.0
V
1
µA
1
µA
10
mV
mA
A
RDSON_N
NFET pin-to-pin Resistance
88
mΩ
RDSON_P
PFET pin-to-pin Resistance
110
mΩ
OSCILLATOR AND TIMING SPECIFICATIONS (NON-I2C-COMPATIBLE INTERFACE TIMING)
fSW
Switching frequency
tR-STEP
LED current ramp up and down
tRU
Current ramp up time
tTORCH-DG
Torch deglitching time
3.8
(–5%)
From end of Command to ILED =
Fullscale
6.3
4.0
4.2
(+5%)
MHz
20
µsec
1.4
msec
9
11.7
msec
31.4
50
mV
1
Bits
ANALOG-TO-DIGITAL (A/D) CONVERTER SPECIFICATIONS
ADCRES
A/D Resolution
VOFF
Offset error
GE
Gain error
Average step size
VLED = 8 V
(–2%)
(+2%)
CONTROL INTERFACE VOLTAGE SPECIFICATIONS
VIL
Low-level threshold voltage (SCL SDA,
ENABLE, TX-MASK, TORCH)
VIH
High-level threshold voltage (SCL SDA,
ENABLE, TX-MASK, TORCH, STROBE
1.8V)
VOL
Low-level output threshold limit (SDA)
VIL
Low-level threshold voltage (STROBE 1.2V)
VIH
High-level threshold voltage (STROBE
1.2V)
(1)
(2)
0.54
1.26
ILOAD = 3 mA
0.84
V
V
0.4
V
0.36
V
V
Min and Max limits are specified 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.
Switching disabled.
4
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ELECTRICAL CHARACTERISTICS (continued)
Limits in standard typeface are for TA = +25°C. Limits in boldface type apply over the full operating ambient temperature
range (−30°C ≤ TA ≤ 85°C). Unless otherwise specified: 2.7V ≤ VIN ≤ 4.4V. (1)(2)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
250
500
µsec
CONTROL INTERFACE TIMING SPECIFICATIONS
TI2C-Start
I2C-Compatible Logic startup time
fSCL
SCL clock frequency
tLOW
Low period of SCL clock
1.3
µsec
tHIGH
High period of SCL clock
0.6
µsec
tHD-STA
Hold time (repeated) START condition
0.6
µsec
tSU-STA
Setup time for a repeated START condition
0.6
µsec
tHD-DAT
Data hold time
0
µsec
tSU-DAT
Data setup time
100
tR
Rise time for SCL and SDA
300
nsec
tF
Fall time for SCL and SDA
300
nsec
tSU-STO
Setup time for stop condition
0.6
µsec
tBUF
Bus free time between stop and start
condition
1.3
µsec
tVD-DAT
Data valid time
tVD-ACK
Data valid acknowledge time
CB
I2C/EN going high
400
20+0.1x
CB
Capacitive load for each bus line
kHz
nsec
0.9
µsec
0.9
µsec
400
pF
5
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TYPICAL CHARACTERISTICS
Unless otherwise specified: TA = 25°C; VIN = 3.6V; CIN1= 10 µF, CIN2= 0.1 µF, COUT1 = 10 µF, COUT2 = 10 µF, L = 1 µH.
1.0
0.78
0.9
0.77
ILED(A)
ILED(A)
0.8
0.7
0.76
0.75
0.6
0.5
0.4
0.74
+25°C
-30°C
+85°C
0.73
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 1. Flash Current vs Brightness Code
Figure 2. 750mA Flash LED Current vs Input Voltage
0.97
0.97
0.96
0.96
0.95
0.95
ILED(A)
ILED(A)
0 1 2 3 4 5 6 7 8 9 101112131415
BRC ( #)
0.94
0.93
0.92
0.91
0.94
0.93
0.92
+25°C
-30°C
+85°C
0.91
0.90
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 3. 930mA Flash LED Current vs Input Voltage
+25°C
-30°C
+85°C
0.90
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 4. LED Efficiency vs Input Voltage at 750mA
3.0
90
2.8
85
2.6
+25°C
-30°C
+85°C
2.4
80
IIN(A)
EFFICIENCY (%)
+25°C
-30°C
+85°C
75
2.2
2.0
1.8
70
65
1.6
+25°C
-30°C
+85°C
1.4
1.2
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 5. LED Efficiency vs Input Voltage at 930mA
Figure 6. Input Current vs Input Voltage at 750mA
6
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TYPICAL CHARACTERISTICS (continued)
Unless otherwise specified: TA = 25°C; VIN = 3.6V; CIN1= 10 µF, CIN2= 0.1 µF, COUT1 = 10 µF, COUT2 = 10 µF, L = 1 µH.
0.070
+25°C
-30°C
+85°C
3.1
0.068
0.066
2.9
0.064
0.062
ILED(A)
IIN(A)
2.7
2.5
0.060
0.058
2.3
0.056
2.1
0.054
1.9
+25°C
-30°C
+85°C
0.052
1.7
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 7. Input Current vs Input Voltage at 930mA
0.050
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 8. 60mA Torch LED Current vs Input Voltage
0.100
85
0.098
EFFICIENCY (%)
0.096
0.094
ILED(A)
0.092
0.090
0.088
0.086
0.084
0.082
80
75
70
+25°C
-30°C
+85°C
65
0.080
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 9. 90mA Torch LED Current vs Input Voltage
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 10. LED Efficiency vs Input Voltage at 60mA
3.6
85
80
3.2
ICL(A)
EFFICIENCY (%)
3.4
75
VOUT= 8.5V @ 930mA
CL = 2.3A
CL = 2.6A
CL = 2.9A
CL = 3.3A
3.0
2.8
2.6
70
65
+25°C
-30°C
+85°C
+25°C
-30°C
+85°C
2.4
2.2
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 11. LED Efficiency vs Input Voltage at 90mA
Figure 12. Inductor Current Limit vs Input Voltage
7
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TYPICAL CHARACTERISTICS (continued)
Unless otherwise specified: TA = 25°C; VIN = 3.6V; CIN1= 10 µF, CIN2= 0.1 µF, COUT1 = 10 µF, COUT2 = 10 µF, L = 1 µH.
2.60
1.0
2.55
VOUT= 8.5V @ 930mA
2.50
0.8
ICL(A)
ILED(A)
0.9
VOUT= 8.5V
0.7
2.46
2.40
2.35
CL = 2.3A
CL = 2.6A
CL = 2.9A
CL = 3.3A
0.6
2.30
+25°C
-30°C
+85°C
2.25
0.5
2.20
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 13. LED Current vs Input Voltage in Current Limit
Figure 14. Inductor Current vs Input Voltage, CL = 2.3A
2.9
2.8
VOUT= 8.5V @ 930mA
3.0
ICL(A)
ICL(A)
2.7
2.6
2.5
+25°C
-30°C
+85°C
Figure 15. Inductor Current vs Input Voltage, CL = 2.6A
Figure 16. Inductor Current vs Input Voltage, CL = 2.9A
4.06
SWITCHING FREQUENCY (MHz)
VOUT= 8.5V @ 930mA
3.2
ICL(A)
3.0
2.8
2.6
2.2
+25°C
-30°C
+85°C
2.0
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
3.6
2.4
2.6
2.2
2.2
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
3.4
2.8
2.4
2.4
2.3
VOUT= 8.5V @ 930mA
3.2
+25°C
-30°C
+85°C
2.0
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 17. Inductor Current vs Input Voltage, CL = 3.3A
8
4.04
4.02
4.00
3.98
3.96
+25°C
-30°C
+85°C
3.94
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 18. Frequency vs Input Voltage
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TYPICAL CHARACTERISTICS (continued)
Unless otherwise specified: TA = 25°C; VIN = 3.6V; CIN1= 10 µF, CIN2= 0.1 µF, COUT1 = 10 µF, COUT2 = 10 µF, L = 1 µH.
0.5
512
448
0.4
TIME (ms)
ISB/ ISD( A)
384
0.3
0.2
256
192
128
+25°C
-30°C
+85°C
0.1
320
64
0.0
0
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VIN(V)
Figure 19. Standby/Shutdown Current vs Input Voltage
0
32
64
96 128 160 192 224 256
FTO (#)
Figure 20. Flash Timeout vs Flash Timeout Code
8
50
7
47
44
6
STEP (mV)
VLED(V)
41
5
4
3
38
35
32
29
2
26
+25°C
-30°C
+85°C
1
0
23
20
0
32
64
96 128 160 192 224 256
CODE (D)
0
Figure 21. ADC Linearity
64
96 128 160 192 224 256
CODE (D)
Figure 22. ADC Step Size
0.6
0.5
0.5
0.4
0.3
DNL (LSB)
0.4
INL (LSB)
32
0.3
0.2
0.1
0.2
0.1
0.0
-0.1
0.0
-0.2
-0.1
-0.3
0
32
64
96 128 160 192 224 256
CODE (D)
Figure 23. ADC INL
0
32
64
96 128 160 192 224 256
CODE (D)
Figure 24. ADC DNL
9
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TYPICAL CHARACTERISTICS (continued)
Unless otherwise specified: TA = 25°C; VIN = 3.6V; CIN1= 10 µF, CIN2= 0.1 µF, COUT1 = 10 µF, COUT2 = 10 µF, L = 1 µH.
5V/DIV
5V/DIV
5V/DIV
VOUT
VOUT
5V/DIV
VLED
VLED
IIN
IIN
1A/DIV
ILED
200
mA/DIV
1A/DIV
200 mA/
DIV
ILED
100 s/DIV
200 s/DIV
Figure 25. Flash Startup
VOUT
Figure 26. Flash Ramp-Up
5V/DIV
VIN
1V/DIV
200 mA/
DIV
ILED
VLED
IIN
ILED
5V/DIV
VOUT
2V/DIV
IIN
1A/DIV
1A/DIV
200 mA/
DIV
100 s/DIV
20 ms/DIV
Figure 27. Flash Ramp-Down
Figure 28. Line-Step During Flash
200 mV/
DIV
VOUT
VLED
200 mV/
DIV
IIN
100 mA/
DIV
VSTROBE
5V/DIV
VLED
5V/DIV
ILED
200 mA/
DIV
1A/DIV
IIN
10 mA/
DIV
ILED
2 ms/DIV
200 ns/DIV
Figure 29. LED Current Ripple at 750mA
10
Figure 30. Flash PWM
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TYPICAL CHARACTERISTICS (continued)
Unless otherwise specified: TA = 25°C; VIN = 3.6V; CIN1= 10 µF, CIN2= 0.1 µF, COUT1 = 10 µF, COUT2 = 10 µF, L = 1 µH.
5V/DIV
5V/DIV
VSTROBE
VLED
VTX
VLED
5V/DIV
5V/DIV
ILED
200 mA/
DIV
200
mA/DIV
ILED
1A/DIV
IIN
1A/DIV
IIN
1 ms/DIV
400 s/DIV
Figure 31. Flash PWM Ramp-Up & Ramp-Down
VTX
5V/DIV
VSTROBE
5V/DIV
200 mA/
DIV
ILED
Figure 32. Tx-Mask Event
VSTROBE
5V/DIV
VLED
5V/DIV
ILED
50 mA/
DIV
IIN
500
mA/DIV
2 ms/DIV
2 ms/DIV
Figure 33. PWM and Tx-Mask Event
Figure 34. Assist PWM
VSTROBE
5V/DIV
VSTROBE
5V/DIV
VLED
5V/DIV
VLED
5V/DIV
ILED
50 mA/
DIV
ILED
50 mA/
DIV
500 mA/
DIV
IIN
500 mA/
DIV
IIN
20 Ps/DIV
10 s/DIV
Figure 35. 60mA Assist PWM Ramp-Up
Figure 36. Assist PWM Down
11
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TYPICAL CHARACTERISTICS (continued)
Unless otherwise specified: TA = 25°C; VIN = 3.6V; CIN1= 10 µF, CIN2= 0.1 µF, COUT1 = 10 µF, COUT2 = 10 µF, L = 1 µH.
VSTROBE
2V/DIV
2V/DIV
VSTROBE
200 mA/
DIV
ILED
200 mA/
DIV
ILED
40 ms/DIV
20 ms/DIV
Figure 37. Edge-Sensitive Strobe
2V/DIV
VSTROBE
200 mA/
DIV
ILED
Figure 38. Level-Sensitive Strobe with Timeout
VTORCH
2V/DIV
ILED
50 mA/
DIV
20 ms/DIV
10 ms/DIV
Figure 39. Level-Sensitive Strobe without Timeout
ILED
IIN
Figure 40. Torch Deglitching Time
10 mA/
DIV
VOUT
1V/DIV
500 mA/
DIV
VLED
1V/DIV
VOUT
5V/DIV
IIN
VLED
5V/DIV
ILED
500 mA/
DIV
10 mA/
DIV
1 ms/DIV
1 ms/DIV
Figure 41. Over-Voltage Protection Fault (OVP)
12
Figure 42. VOUT Short to GND Fault
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TYPICAL CHARACTERISTICS (continued)
Unless otherwise specified: TA = 25°C; VIN = 3.6V; CIN1= 10 µF, CIN2= 0.1 µF, COUT1 = 10 µF, COUT2 = 10 µF, L = 1 µH.
1V/DIV
VLED
VOUT
VLED
1V/DIV
VOUT
2V/DIV
2V/DIV
500 mA/
DIV
10 mA/
DIV
IIN
ILED
200 mA/
DIV
20 mA/
DIV
IIN
ILED
400 s/DIV
1 ms/DIV
Figure 43. VLED Short to GND Fault
Figure 44. Indicator Short to GND Fault
VIN
2V/DIV
2V/DIV
VOUT
VOUT
VLED
2V/DIV
VLED
500 mA/
DIV
20 mA/
DIV
ILED
5V/DIV
5V/DIV
IIN
ILED
50 mA/
DIV
100 ms/DIV
400 s/DIV
Figure 45. Indicator Open Fault
Figure 46. Under-Voltage Lockout (UVLO)
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BLOCK DIAGRAM
VIN
8-Bit Analog to Digital
Converter
VREF
UVLO
LED
Open/Short
Detect
TX-MASK
TORCH/ASSIST CTRL
TORCH
2
STROBE
EN
I C INTERFACE/
CONTROL LOGIC/
REGISTERS
LED Current
Control
FLASH CTRL
VLED
TIME-OUT CTRL
gm
SCL
0.3V
RC
SDA
-
+
VOUT
SW
Driver
CC
OVP/Short
Detect
SW
PGND
SW
Driver
SWITCH
CONTROLLER
SGND
THERMAL
SHUTDOWN
OSC
4 MHz
RAMP
LM3565
CURRENT
LIMIT
gm
¦
IC
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FUNCTIONAL DESCRIPTION
Circuit Description
Overview
The LM3565 is a high-power white LED flash driver capable of delivering up to 930 mA of LED current into two
series LEDs. The device incorporates a 4 MHz constant frequency, synchronous, current mode PWM boost
converter, and a single high-side current source to regulate the LED current over the 2.5V to 5.5V input voltage
range.
Circuit Components
Synchronous Boost Converter
The LM3565 operates in boost mode in LED Flash or Assist operation. In LED boost mode, the PWM converter
switches and maintains at least 300 mV across the current source. This minimum headroom voltage ensures that
the current sink remains in regulation.
High-Side Current Source
The High-Side current source of the LM3565 is capable of driving two LEDs in series. The flash current range is
480 mA to 930 mA in 30 mA steps with a default current equal to 750 mA.
Additionally, the high-side current source is capable of supporting two Assist/Torch current levels (continuous
current) equal to 60 mA (default) or 90 mA.
A/D Converter
An internal 8-bit ADC can be utilized to measure the input voltage and the LED voltage during a flash or assist
event. If the ADC input voltage measurement bit is set to a '1' (IV bit in register 0x09), the digitized value of the
LM3565's input voltage can be read back from the Input Voltage ADC Register (0x0A). The input voltage is
sampled before the start of the flash or assist event if the FON bit in register 0x09 is set to a '0' and 2ms after the
LED current ramp up is completed if it is set to a '1'. The LED voltage can be read back from the LED Voltage
ADC Register (0x0B) if the ADC LED voltage measurement bit is set to a '1' (LV bit in register 0x09). The LED
voltage is sampled 2ms after the LED current is ramped up.
ENABLE Pin
The ENABLE pin on the LM3565 places the part into Shutdown Mode (low) or Standby Mode (high). In
Shutdown Mode, most of the control functionality is disabled. In shutdown, it is possible to enable the part
through the use of the Torch pin. In standby, the LM3565 can be controlled via the I2C-compatible interface or
the Torch and Strobe pins if the part has been configured to do so. The ENABLE pin must be held low before
power is applied to the LM3565.
SDA and SCL Pins
The SDA and SCL pins are the I2C-compatible control interface inputs for the LM3565. SDA is the interface data
input and SCL is the interface clock input.
STROBE Pin
The Strobe pin of the LM3565 provides an external method for initiating a flash or assist event. In most cases,
the Strobe pin is connected to an imaging module so that the image capture and flash event are synchronized.
The Strobe pin is only functional when the LM3565's Output Enable (OEN in 0x07) and Strobe Signal Mode
(SEN in 0x06) bits are set ('1'). The Strobe pin can be configured to be an edge-sensitive or level-sensitive input
by setting the Strobe Signal Usage bit (SSU in 0x06. '1' = Level, '0' = Edge). In edge-sensitive mode, a rising
edge transition ('0' to '1') will start the flash event and the internal flash timer will terminate the event. In levelsensitive mode, a rising edge transition ('0' to '1') will start the flash event and a falling edge transition ('1' to '0')
or the internal flash timer, which ever occurs first, will terminate the event.
Additionally, the Strobe pin can be used to pulse-width modulate (PWM) the diode current during a flash or assist
event. In flash mode, by setting the PWM bit in the Strobe signaling register (PWM in register 0x06) to a '1', and
toggling the Strobe pin high and low, the diode current will transition between the target flash current and a
reduced current value selected in register 0x06 (SPL3-SPL0). When the Strobe pin is high ('1'), the flash current
is equal to the target LED current. When the Strobe pin is low ('0'), the flash current is equal to the target LED
current minus the reduction current value, or 60 mA, whichever is higher. The diode current is ramped up and
down during the transitions between the full current state and the reduced current state.
15
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In assist mode, by setting the PWM bit in the Strobe signaling register (PWM in register 0x06) to a '1', and
toggling the Strobe pin high and low, the diode current will transition between the target assist current and 10
mA. When the Strobe pin is high ('1'), the assist current is equal to the target LED current. When the Strobe pin
is low ('0'), the assist current is equal to 10 mA. The diode current is always ramped up to 90 mA, then reduced
to 60 mA if the assist target current is set to 60 mA. The transition between the full-assist current and the 10 mA
current level is done in one step.
TORCH Pin
The Torch pin of the LM3565, depending on the state and configuration, allows the user to enable Torch/Assist
Mode without having to write the command through the I2C bus. In standby mode, the external torch mode bit
(ETEN bit in register 0x03) must be set to a '1' to allow an external torch (default value = '1'). The torch mode
current is equal to the Assist mode current level stored in register 0x02 (AS0 bit, default value = '0' or 60 mA). In
shutdown mode, driving the Torch pin high will enable the LM3565 and drive the flash LEDs at 60 mA.
TX-MASK Pin
The TX-Mask pin provides the RF PA a direct method to reduce the flash current by a predetermined value
stored in the TX-Mask register (0x03), to prevent a battery over-current fault. When the TX-Mask pin is set low,
the normal target current is realized. When the TX-Mask pin is set high, the flash current is reduced. The flash
current is not ramped during the transition from full-scale to the reduced level; the flash current is ramped when
transitioning back to the full-scale value from the reduced value. As in the Fflash PWM Mode, the lowest flash
current is set to 60 mA.
Fault Protections
The LM3565 has numerous internal fault protection mechanisms to help prevent damage to the LM3565 as well
as the system in the event of a fault. Most fault conditions will cause the LM3565 to enter Shutdown Mode and
will report a fault to the fault register (0x08) or (0x09). The faults that can be detected are as follows:
• Over-Voltage Protection (VOUT)
• Short-Circuit Protection (VOUT and VLED)
• Over-Temperature Protection
• Flash Time-Out
• TX-Mask Event
• Under-Voltage Lock-Out
• Input Low Voltage Detect
• Inductor Current Limit (not reported)
• Output Capacitor Open Protection
I2C Flash
Strobe
Flash
Shutdown
Standby
Output On
External
Torch
Assist Light
External
Torch
Figure 47. Mode Diagram
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I2C-Compatible Interface
Data Validity
The data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, the state
of the data line can only be changed when CLK is LOW.
SCL
SDA
data
change
allowed
data
valid
data
change
allowed
data
valid
data
change
allowed
Figure 48. Data Validity Diagram
A pull-up resistor between VIO and SDA must be greater than [ (VIO-VOL) / 3mA] to meet the VOL requirement
on SDA. Using a larger pullup resistor results in lower switching current with slower edges, while using a smaller
pull-up results in higher switching currents with faster edges.
Start and Stop Conditions
START and STOP conditions classify the beginning and the end of the I2C-compatible session. A START
condition is defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. A STOP condition is
defined as the SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C-compatible master always
generates START and STOP conditions. The I2C-compatible bus is considered to be busy after a START
condition and free after a STOP condition. During data transmission, the I2C-compatible master can generate
repeated START conditions. First START and repeated START conditions are equivalent, function-wise. The
data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, the state of
the data line can only be changed when CLK is LOW.
SDA
SCL
S
P
START condition
STOP condition
Figure 49. Start and Stop Conditions
Transferring Data
Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) being transferred first.
Each byte of data has to be followed by an acknowledge bit. The acknowledge related clock pulse is generated
by the master. The master releases the SDA line (HIGH) during the acknowledge clock pulse. The LM3565 pulls
down the SDA line during the 9th clock pulse, signifying an acknowledge. The LM3565 generates an
acknowledge after each byte has been received.
After the START condition, the I2C-compatible master sends a chip address. This address is seven bits long
followed by an eighth bit which is a data direction bit (R/W). The LM3565 address is 30h. For the eighth bit, a '0'
indicates a WRITE and a '1' indicates a READ. The second byte selects the register to which the data will be
written. The third byte contains data to write to the selected register.
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ack from slave
ack from slave
start
msb Chip Address lsb
w
ack
msb Register Add lsb
ack
start
Id = 0x30
w
ack
addr = 0x07
ack
ack from slave
msb
DATA
lsb
ack
stop
ack
stop
SCL
SDA
data = 0x0B
NOTE: w = write (SDA = "0"), ack = acknowledge (SDA pulled down by the slave), id = chip address, 30h for LM3565
Figure 50. Write Cycle
I2C-Compatible Chip Address
The chip address for LM3565 is 0110000, or 30hex.
MSB
LSB
ADR6
bit7
ADR5
bit6
ADR4
bit5
ADR3
bit4
ADR2
bit3
ADR1
bit2
ADR0
bit1
0
1
1
0
0
0
0
R/W
bit0
2
I C Slave Address (chip address)
Internal Registers of LM3565
Table 1. Summary of LM3565 Registers
REGISTER
INTERNAL HEX ADDRESS
POWER ON VALUE
Design Information Register
0x00
0011 0100
Version Control Register
0x01
0000 0110
Current Set Register
0x02
0000 1001
TX-Mask Register
0x03
0111 1011
Low Voltage Control Register
0x04
0100 0100
Timing Control Register
0x05
0010 0011
Strobe Signaling Register
0x06
1100 1000
Output Mode Register
0x07
0000 0000
Fault and Info Register
0x08
0000 0000
ADC Control Register
0x09
0000 0000
Input Voltage ADC Register
0x0A
0000 0000
LED Voltage ADC Register
0x0B
0000 0000
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Register Definitions (bold table values = default register settings)
Design Information Register
Address: 0x00
Definition: MN3 MN2 MN1 MN0 MO3 MO2 MO1 MO0
Default:
0
0
1
1
0
1
0
0
MN3–MN0: Manufacturer ID = 0011
MO3–MO0: Model ID = 0100
Version Control Register
Address: 0x01
Definition:
Default:
RF3
RF2
RF1
RF0
DR3
DR2
DR1
DR0
0
0
0
0
0
1
1
0
RF3–RF0: Unused
DR3–DR0: Design Revision = 0110
Current Set Register
Address: 0x02
Definition:
Default:
NA
NA
NA
AS0
FS3
FS2
FS1
FS0
0
0
0
0
1
0
0
1
AS0: Assist Current Level Bit. '0' = 60 mA, '1' = 90 mA
FS3-FS0: Flash Set Current bits. Refer to Table 2 for details.
Table 2. Flash Currents
FS3
FS2
FS1
FS0
Flash
Current
Level
0
0
0
0
480 mA
0
0
0
0
0
1
0
540 mA
0
0
1
1
570 mA
0
1
0
0
600 mA
0
1
0
1
630 mA
0
1
1
0
660 mA
0
1
1
1
690 mA
1
0
0
0
720 mA
1
0
0
1
750 mA
1
0
1
0
780 mA
1
0
1
1
810 mA
1
1
0
0
840 mA
1
1
0
1
870 mA
1
1
1
0
900 mA
1
1
1
1
930 mA
510 mA
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Tx-Mask Register
Address: 0x03
Definition: TXEN TXR3 TXR2 TXR1 TXR0 ICL1 ICL0 ETEN
Default:
0
1
1
1
1
0
1
1
TXEN: TX-Mask Enable Bit. '0' = TX-Mask Disabled. '1' = TX-Mask Enabled.
TXR3-TXR0: TX-Mask Current Reduction Bits. See TX-Mask Flash Current Reduction Levels table.
ICL1-ICL0: Inductor Peak Current Limit Bits. See Peak Inductor Current Limit Levels table.
ETEN: External Torch Enable Bit. '0' = External Torch Mode disabled in standby.
'1' = External Torch Mode allowed/enabled in standby.
Table 3. TX-Mask Flash Current Reduction Levels
TXR3
TXR2
TXR1
TXR0
Flash Reduction
Level
0
0
0
0
30 mA
0
0
0
1
60 mA
0
0
1
0
90 mA
0
0
1
1
120 mA
0
1
0
0
150 mA
0
1
0
1
180 mA
0
1
1
0
210 mA
0
1
1
1
240 mA
1
0
0
0
270 mA
1
0
0
1
300 mA
1
0
1
0
330 mA
1
0
1
1
360 mA
1
1
0
0
390 mA
1
1
0
1
420 mA
1
1
1
0
450 mA
1
1
1
1
480 mA
Table 4. Peak Inductor Current Limit Levels
ICL1
ICL0
0
0
Peak Inductor Current Limit
2.3A
0
1
2.6A
1
0
2.9A
1
1
3.3A
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LVEN: Flash Low Voltage Checking Enable Bit. '0' = Disabled, '1' = Enabled
LVL2-LVL0: Flash Low Voltage Detection Level. See Table 5.
LVR1-LVR0: Flash Low Voltage Current Reduction Level.
See Table 5.
LVRS: State Machine Reset Bit. '0' = Normal operation, '1' = RESET
Table 5. Flash Low Voltage Detection Levels
LVL2
LVL1
LVL0
Input Voltage
Level
0
0
0
3.0V
0
0
1
3.1V
0
1
0
3.2V
0
1
1
3.3V
1
0
0
3.4V
1
0
1
3.5V
1
1
0
3.6V
1
1
1
3.7V
Table 6. Flash Low Voltage Current Reduction Values
ICL1
ICL0
Peak Inductor Current Limit
0
0
150 mA
0
1
180 mA
1
0
210 mA
1
1
240 mA
Timing Control Register
Address: 0x05
Definition:
Default:
FT7
FT6
FT5
FT4
FT3
FT2
FT1
FT0
0
0
1
0
0
0
1
1
FT7-FT0: Flash Timeout Duration Bits.
Flash Time = (2 + N x 2)ms, where 0 ≤ N ≤ 255
'0x00' = 2ms, '0x01' = 4ms, '0x02' = 6ms, . . ., '0x22' = 126ms, . . ., '0xFF' = 512 ms.
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Strobe Signaling Register
Address: 0x06
Definition:
Default:
SEN SSU PWM SPL3 SPL2 SPL1 SPL0 SLL
1
1
0
0
1
0
0
0
SEN: = Strobe Enable Bit. '0' = Disabled, '1' = Enabled
SSU: Strobe Signal Usage Bit. '0' = edge-sensitive, '1' = Level Sensitive
PWM: Flash PWM w/ Strobe Signal Enable bit. '0' =Disabled, '1' = Enabled
SPL3-SPL0: Stobe PWM Flash Current Reduction Level.
See Strobe PWM Flash Current Reduction Levels table.
SLL: Strobe Logic Level Bit. '0' = 1.2V Logic, '1' = 1.8V Logic
Table 7. Strobe PWM Flash Current Reduction Levels
SPL3
SPL2
SPL1
SPL0
Flash Current Level
0
0
0
0
30 mA
0
0
0
1
60 mA
0
0
1
0
90 mA
0
0
1
1
120 mA
0
1
0
0
150 mA
0
1
0
1
180 mA
0
1
1
0
210 mA
0
1
1
1
240 mA
1
0
0
0
270 mA
1
0
0
1
300 mA
1
0
1
0
330 mA
1
0
1
1
360 mA
1
1
0
0
390 mA
1
1
0
1
420 mA
1
1
1
0
450 mA
1
1
1
1
480 mA
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Output Mode Register
Address: 0x07
Definition:
x
x
x
x
OEN
x
Default:
0
0
0
0
0
0
OM1 OM0
0
0
OEN: Output Enable Bit. '0' = Disabled, '1' = Enabled
OM1-OM0: Output Mode Bits. See Output Modes table.
Table 8. Output Modes
OM1
OM0
Output Mode
0
0
External Torch
0
1
Do Not Use
1
0
Assist Light
1
1
Flash
Fault and Info Register
Address: 0x08
Definition: OVP
Default:
0
SC
OTP
TO
0
0
0
TXM RFU
0
0
ILV UVLO
0
0
OVP: Over-Voltage Protection Fault Flag
SC: Short Circuit Fault Flag
OTP: Over Temperature Protection Flag
TO: Flash Timeout Flag TXM: TX-Mask Event Flag
ILV: Input Low Voltage Fault Flag
UVLO: Under Voltage Lock Out Fault Flag
ADC Control
Address: 0x09
Definition:
IV
LV
FON
CO
Default:
0
0
0
0
RFU RFU RFU RFU
0
0
0
0
IV: ADC Input Voltage Measurement Enable Bit. '0' = Disabled, '1' = Enabled
LV: ADC LED Voltage Measurement Enable Bit. '0' = Disabled, '1' = Enabled
FON: Input Voltage Measurement during Flash Bit. '0' = Without Flash Current, '1' = With Flash Current
CO: Open Output Capacitor Fault Bit. '0' = Normal Operation, '1' = Missing Output Capacitor
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Input Voltage ADC Register
Address: 0x0A
Definition: IVD7 IVD6 IVD5 IVD4 IVD3 IVD2 IVD1 IVD0
Default:
0
0
0
0
0
0
0
0
IVD7-IVD0: ADC Input Voltage Measurement Data
LED Voltage ADC Register
Address: 0x0B
Definition: LED7 LED6 LED5 LED4 LED3 LED2 LED1 LED0
Default:
0
0
0
0
0
0
0
0
LED7-LED0: ADC LED Voltage Measurement Data
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Control State Diagram
Shutdown
N
Y
Torch
Torch
High?
N
Y
EN Pin
High?
Standby
Low Vin
EN Bit
= µ1¶?
Y
N
Output EN
Bit = µ1¶?
Current
Reduction
N
N
Y
Y
Low Vin
Detected?
N
Start
Flash
Strobe EN
Bit = µ1¶?
Y
Strobe Pin
High?
Start
Timeout
Timer
N
Note 1
Y
External
Torch?
N
N
Assist?
Y
N
N
Y
Torch
High?
N
Start
Assist
Assist
Active
Strobe Pin
Low?
Y
N
Y
TX-Mask
Pin High?
Y
Current
Reduction
Y
Torch
Active
Y
Y
TX-Mask
EN Bit
= µ1¶?
Current
Reduction
Y
Torch
High?
Clear
Output
Enable
Bit
Y
Time-Out
Done?
Output
EN Bit
= µ1¶?
Strobe
Start?
N
Y
N
Output
EN Bit
= µ1¶?
PWM
Strobe
EN?
Y
N
N
Y
Strobe Pin
High?
Strobe
Start?
Y
PWM
Strobe
EN?
N
Level
Strobe?
Y
Strobe Pin
High?
N
Y
Strobe Pin
Low?
Y
Current
Reduction
N
Note 1: Flash time-out is always checked during flash.
Flash is terminated when time-out is done.
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I2C Mode Truth Table
OEN
OM1
OM0
ETEN
SEN
TORCH
STROBE
Mode
0
0
0
0
X
X
X
Standby
0
0
0
1
X
0
X
Standby
0
0
0
1
X
1
X
Ext Torch
0
0
1
X
X
X
X
Standby
0
1
0
X
X
X
X
Standby
0
1
1
X
X
X
X
Standby
1
0
0
X
X
0
X
Standby
1
0
0
1
X
1
X
Ext Torch
1
0
1
X
0
X
X
RFU
1
1
0
X
0
X
X
Assist
1
1
1
X
0
X
X
Internal Flash
1
0
0
X
1
X
0
Standby
1
0
1
X
1
X
1
RFU
1
1
0
X
1
X
1
Strobe Assist
1
1
1
X
1
X
1
Strobe Flash
26
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Product Folder Links: LM3565
LM3565
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SNVS957 – JANUARY 2013
APPLICATION INFORMATION
Torch or Assist (Continuous Current) Operation
There are two different continuous current modes on the LM3565: Torch and Assist.
Torch Mode is enabled through the use of the dedicated Torch pin. The Torch pin functionality can be enabled
and disabled by setting the value of the ETEN bit in the TX-Control Register (Address 0x03). ETEN = '1' allows
an external Torch while ETEN = '0' does not.
The primary method to enable Assist Mode is by setting the Output Mode bits (OM1 and OM0) to '10' and setting
the Output Enable bit (OEN) to a '1' in the Control Register (0x07). Assist Mode will remain active in I2Ccompatible Mode until the OEM bit is set to '0'.
The secondary Assist Mode enabling method involves using the Strobe pin. By setting the SEN bit in the Stobe
Signaling Register (Address 0x06) to a '1', then setting the Output Mode bits (OM1 and OM0) to '10' and setting
the Output Enable bit (OEN) to a '1' in the Control Register (0x07), the LM3565 will be configured to enable
Assist Mode upon the Strobe pin transitioning state from low to high. In this configuration, Assist Mode will
remain active until the OEN bit is set to '0'. Transitioning the Strobe pin from high to low does not automatically
clear the OEN. In Assist Mode, the Strobe Signal Usage bit (SSU in Strobe Signaling Register 0x06) is ignored,
and the Strobe pin is always set to be edge sensitive.
The LM3565 can drive two LEDs at continuous current levels of 60 mA or 90 mA. The current is set in the
Current Set Register utilizing the AS0 bit (Address 0x02, AS0). Writing a '0' (default) sets the assist current to 60
mA while writing a '1' sets the assist current to 90 mA.
In Torch or Assist Mode, the LED current is ramped up to 90 mA in 30 mA steps at 20 µs intervals, then reduced
to 60 mA if the assist target current is set to 60 mA. The assist current is terminated in one step.
Flash (Pulsed Current) Operation
A flash event using the LM3565 can be initiated though the I2C-compatible control interface, and through the use
of the Strobe pin.
When using the I2C-compatible Control Mode, a flash event is initiated when the Output Mode bits (OM1 and
OM0) are set to '11' and the Output Enable bit (OEN) is set to a '1' in the Control Register (0x07). In I2Ccompatible Mode, the flash event will remain active as long as the OEN bit is set to a '1' and will terminate upon
a time-out event. The safety timer duration can be set in 2 ms intervals ranging from 2 ms to 512 ms by writing
the desired value to the FT7-FT0 bits in the Timer Register (Address 0x05, with the default timer set to 72
msec.).
The Strobe pin provides added system flexibility in that it allows an additional external device (Camera Module,
GPU etc.) to trigger a flash event. To initiate a Strobe event in I2C-compatible Control Mode, the Strobe Enable
(SEN) bit in the Strobe Signaling Register (0x06) must first be set to a '1', and the Output Enable (OEN) bits and
Output Mode bits (OM1 and OM0) in the Control Register (Address 0x07) must be set to '1's.
Following the setting of the SEN and OEN bits, the user must choose to have an edge-sensitive or level-sensitive
strobe event. Writing a '1' to the Strobe Signal Usage (SSU) bit in the Control Register (Address 0x06), the
LM3565 will be configured to be level sensitive, while writing a '0' configures the part to be edge-sensitive. In
both cases, the strobe flash event is started upon the Strobe pin being driven high.
In an edge-sensitive event, the flash duration will stay active until the flash duration timer lapses regardless of
the state of the Strobe pin. If a level-sensitive strobe is used, the flash event will remain active as long as the
Strobe pin is held high and as long as the flash duration time has not lapsed.
In Flash Mode, the LED current is ramped up and down in 30 mA steps at 20 µs intervals.
At the end of a flash event, whether initiated through the Control Register or Strobe pin, the LM3565 will force
the OEN bit to a '0' and will place the LM3565 back into the Standby state.
27
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Fault Protections
The LM3565 has a number of fault protection mechanisms designed to not only protect the LM3565 itself, but
also to reset the system. Active fault protections include:
• Over-Voltage Protection (VOUT)
• Short-Circuit Protection (VOUT and VLED)
• Over-Temperature Protection
• Flash Time-Out
• Under-Voltage Lock-Out (UVLO)
• Output Capacitor Open Protection
In the event that any of these faults occur, the LM3565 will set a flag in the appropriate Fault Register (Address
0x08 or 0x09) and place the part into standby. Normal operation cannot resume until the fault has been fixed and
an I2C read of the fault register (0x08 and/or 0x09) has been completed. All faults are cleared upon reading the
Fault Registers (0x08 and 0x09).
Output Over-Voltage Protection (OVP)
An OVP fault is triggered when the output voltage of the LM3565 reaches a value greater than 9.5V (typ). The
OVP condition is cleared when the output voltage (VOUT) is able to operate below 9.5V. An output capacitor or an
LED that have become an open circuit can cause an OVP event to occur. This fault is reported to the OVP fault
bit in the Fault Register (bit7 in address 0x05).
Output and LED Short Circuit Protection (SC)
An SC fault is triggered when the output voltage (VOUT) and/or the LED voltage (VLED) does not reach 0.8V in
0.5 ms. The short circuit condition is cleared when the output (VOUT) is allowed to reach its steady state target
and when the LED voltage rises above 0.8V. A shorted output capacitor or a shorted LED could cause this fault
to occur. This fault is reported to the SC fault bit in the Fault Register (bit6 in address 0x08).
Over-Temperature Protection (OTP)
An OTP fault is triggered when the diode junction temperature of the LM3565 reaches an internal temperature of
around 150°C. The OTP condition is cleared when the junction temperature falls below 115°C and the fault
register is read. A printed circuit board (PCB) with poor thermal dissipation properties and very high ambient
temperatures (greater that 85°C) could cause this fault to occur. Refer to Texas Instruments Application Note:
AN-1112: DSBGA Wafer Level Chip Scale Package for more information regarding proper PCB layout. This fault
is reported to the OTP fault bit in the Fault Register (bit5 in address 0x08).
Flash Time-Out (TO)
The TO fault will be triggered whenever a flash is initiated with a level-sensitive Strobe event controlled by a
camera module and the Strobe pulse duration exceeds the selected Flash Time-out duration. This fault is
reported to the TO fault bit in the Fault Register (bit4 in address 0x08). This bit only gets set when PWM Mode is
disabled.
Under-Voltage Lock-Out (UVLO)
An Under-Voltage Lock-Out (UVLO) fault occurs when the input voltage at the LM3565 drops below 2.4V (typ).
When this fault occurs, the LM3565 will be forced into Standby Mode and the UVLO bit will be set to a '1'. To exit
a UVLO state, the input voltage to the LM3565 must increase by 100 mV (typ.) and the UVLO Fault bit must be
cleared. This fault is reported to the UVLO fault bit in the Fault Register (bit0 in address 0x08).
Output Capacitor Open Protection (CO)
An Output Capacitor Open fault is triggered when the LM3565 detects that the capacitance at the VOUT pin has
dropped below the acceptable value (typically 0.1 µF). This fault indicates that the output capacitors are either
disconnected or damaged and is reported to the Output Capacitor fault bit in the ADC Control Register (bit4 in
address 0x09). Once an Output Capacitor Open fault is detected, the State Machine Reset bit (LVRS) in the Low
Voltage Control register (0x04) has to bo toggled between a '1' and a '0' in order for normal operation to resume.
28
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Input Low Voltage Flag (ILV)
The LM3565 has an Input Low Voltage (ILV) detection mechanism that sets the ILV flag (bit1 in address 0x08)
when this feature is enabled (LVEN = 1, bit6 in address 0x04) and the input voltage is below the threshold set in
the Low Voltage Control Register (LVL2-LVL0 in address 0x04). The input voltage is only monitored before the
start of a flash event. This is a reporting flag bit and not a fault bit. The ILV flag bit does not halt or reset the
LM3565.
TX-Mask Flag (TXM)
The LM3565 has a Transmit Interrupt flag bit (TXM, bit 3 in address 0x08) that gets set if the TX-Mask feature is
enabled (TXEN = 1, bit7 in address 0x03) and if the TX-Mask pin is high, indicating a TX-Mask event. This is a
reporting flag bit and not a fault bit. The TXM flag bit does not halt or reset the LM3565.
Table 9. Application Circuit Components List
Component
Manufacturer
Value
Part Number
Current/Voltage Rating (Resistance)
L
Toko
1µH
1239AS-H-1R0N
ISAT = 3A (59 mΩ)
COUT1, COUT2
Murata
10 µF
GRM21BR61C106KE15
16 V
CIN1
Murata
10 µF
GRM188R60J106ME47
6.3 V
CIN2
Murata
0.1 µF
GRM155R71C104KA88
16 V
Inductor Current Limit
To prevent damage to the LM3565's inductor and to limit the power drawn by the LM3565 during a flash event,
an Inductor Current Limit circuit is present. The LM3565 monitors the current through the inductor during the
charge phase of the boost cycle. In the event that the inductor current reaches the current limit, the NFET of the
converter will terminate the charge phase for that cycle. The process will repeat itself until the flash event has
ended or until the input voltage increases to the point where the peak current is no longer reached. Hitting the
peak inductor current limit will not disable the part. It will however limit the output power delivery to the LEDs.
The inductor current limit can be set to 2.3A, 2.6A (default), 2.9A or 3.3A depending on the values of the ICL1
and ICL0 bits in the TX-Masking Register (Address 0x03). The peak inductor current limit value can be used to
help size the inductor to the appropriate saturation current level. For more information on inductor sizing, refer to
the INDUCTOR SELECTION section of this datasheet.
Inductor Selection
The LM3565 is designed to use a 1µH inductor. When the device is boosting (VOUT > VIN) the inductor is one of
the biggest sources of efficiency loss in the circuit. Therefore, choosing an inductor with the lowest possible
series resistance is important. Additionally, the saturation rating of the inductor should be greater than the
maximum operating peak current of the LM3565. This prevents excess efficiency loss that can occur with
inductors that operate in saturation and prevents over-heating of the inductor and possible damage. For proper
inductor operation and circuit performance ensure that the inductor saturation and the peak current limit setting of
the LM3565 (2.3A, 2.6A (default), 2.9A or 3.3A) is greater than IPEAK. IPEAK can be calculated by:
ILOAD
IPEAK =
K
VOUT
u
VIN
+ 'IL
where
VIN u
'IL =
( VOUT - VIN)
2 u fSW u L u VOUT
29
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Capacitor Selection
The LM3565 requires 3 external capacitors for proper operation (CIN = 10 µF recommended (4.7 µF min) and 2 ×
COUT = 10 µF ). An additional 0.1 µF input capacitor placed right next to the VIN pin is recommended. Surfacemount multi-layer ceramic capacitors are recommended. These capacitors are small, inexpensive, and have very
low equivalent series resistance (ESR
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