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LT3486 Dual 1.3A White LED Step-Up Converters with Wide Dimming FEATURES

DESCRIPTIO

Wide (1000:1) PWM Dimming Range with No ColorShift Independent Dimming and Shutdown Control of the LED Drivers Drives Up to 16 White LEDs at 25mA (8 per Driver) from a Single Li-Ion Cell Drives Up to 16 White LEDs at 100mA (8 per Driver) from 12V Supply 3% LED Current Programming Accuracy Open LED Protection: 36V Clamp Voltage Fixed Frequency Operation: Up to 2MHz Wide Input Voltage Range: 2.5V to 24V Low Shutdown Current: ICC < 1A Overtemperature Protection Available in (5mm x 3mm x 0.75mm) 16-Pin DFN and 16-Pin Thermally Enhanced TSSOP Packages
The LT (R)3486 is a dual step-up DC/DC converter specifically designed to drive up to 16 White LEDs (8 in series per converter) at constant current from a single Li-Ion cell. Series connection of the LEDs provides identical LED currents resulting in uniform brightness. The two independent converters are capable of driving asymmetric LED strings. The dimming of the two LED strings can be controlled independently via the respective CTRL pins. An internal dimming system allows the dimming range to be extended up to 1000:1 by feeding a PWM signal to the respective PWM pins. The LT3486 operating frequency can be set with an external resistor over a 200kHz to 2MHz range. A low 200mV feedback voltage (3% accuracy) minimizes power loss in the current setting resistor for better efficiency. Additional features include output voltage limiting when LEDs are disconnected and overtemperature protection. The LT3486 is available in a space saving 16-pin DFN (5mm x 3mm x 0.75mm) and 16-pin thermally enhanced TSSOP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Patent Pending.
APPLICATIO S

Notebook PC Display LED Camera Light for Cell Phones Car Dashboard Lighting Avionics Displays
TYPICAL APPLICATIO
Li-Ion Powered Driver for Camera Flash and LCD Backlighting
VIN 3V TO 4.2V
10F 2.2F LED1 AOT3218 DIMMING 1 OFF ON SW1 OVP1 CTRL1 SHDN PWM1 OFF ON RFB1 0.62 0.1F FB1 VC1 100k RT 63.4k LT3486 L1 10H VIN L2 10H SW2 OVP2 CTRL2 REF PWM2 FB2 VC2 2.8k 4.7nF RFB2 8.06
3486 TA01a
90 2.2F 8 LEDs EFFICIENCY (%) MOVIE MODE ILED1 = 175mA 85 FLASH MODE ILED1 = 320mA
DIMMING 2
25mA
80
75
0.1F 70 8 LEDS/25mA 3 3.2 3.4 3.6 VIN (V) 3.8 4 4.2
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Efficiency vs VIN
3486 TA01b
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LT3486 ABSOLUTE AXI U RATI GS (Note 1)
Operating Temperature Range (Note 2) ...-40C to 85C Storage Temperature Range DFN ...................................................-65C to 125C TSSOP ............................................... -65C to 150C Maximum Junction Temperature .......................... 125C Lead Temperature (Soldering, 10sec, TSSOP) ...... 300C Input Voltage (VIN) ...................................................25V SHDN Voltage ..........................................................25V SW1, SW2 Voltages .................................................40V OVP1, OVP2 Voltages ...............................................40V CTRL1, CTRL2 Voltages ...........................................10V PWM1, PWM2 Voltages ...........................................10V FB1, FB2 Voltages .....................................................10V
PACKAGE/ORDER I FOR ATIO
SW1 VIN OVP1 RT VC1 FB1 CTRL1 PWM1 1 2 3 4 5 6 7 8 17 16 SW2 15 REF 14 OVP2 13 SHDN 12 VC2 11 FB2 10 CTRL2 9 PWM2
ORDER PART NUMBER LT3486EDHC
DHC PART MARKING 3486
DHC PACKAGE 16-LEAD (5mm x 3mm) PLASTIC DFN EXPOSED PAD (PIN 17) IS GND MUST BE SOLDERED TO PCB TJMAX = 125C, JA = 43C/W, JC = 4C/W
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER Minimum Operating Voltage Maximum Operating Voltage Feedback Voltage (FB1, FB2) Offset between FB1 and FB2 Feedback Pin Bias Current (FB1, FB2) Quiescent Current Switching Frequency Oscillator Frequency Range Nominal RT Pin Voltage
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 3V, VCTRL1 = 3V, VCTRL2 = 3V, VPWM1 = 3V, VPWM2 = 3V, VSHDN = 3V, unless otherwise noted.
CONDITIONS MIN 2.5
VOS = |FB1-FB2| VFB1 = VFB2 = 0.2V (Note 3) VFB1 = VFB2 = 1V SHDN = 0V, CTRL1 = CTRL2 = 0V RT = 53.6k (Note 4) RT = 53.6k
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TOP VIEW SW1 1 VIN 2 OVP1 3 RT 4 VC1 5 FB1 6 CTRL1 7 PWM1 8 17 16 SW2 15 REF 14 OVP2 13 SHDN 12 VC2 11 FB2 10 CTRL2 9 PWM2
ORDER PART NUMBER LT3486EFE
FE PART MARKING 3486EFE
FE PACKAGE 16-LEAD PLASTIC TSSOP EXPOSED PAD IS GND (PIN 17) MUST BE SOLDERED TO PCB
TJMAX = 125C, JA = 38C/W, JC = 10C/W
TYP
MAX 24 206 6 100 14 1 1.25 2000
UNITS V V mV mV nA mA A MHz kHz V
194 0 10
0.75 200
200 3 45 9 0.1 1 0.54
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LT3486
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 3V, VCTRL1 = 3V, VCTRL2 = 3V, VPWM1 = 3V, VPWM2 = 3V, VSHDN = 3V, unless otherwise noted.
PARAMETER Maximum Duty Cycle CONDITIONS RT = 53.6k RT = 20.5k RT = 309k ISW1 = ISW2 = 0.75A VSW1 = VSW2 = 10V I = 5A
ELECTRICAL CHARACTERISTICS
MIN 90
TYP 96 90 98 1.3 300 0.1 220 120 0.85 1.5 25 25 1 36
MAX
UNITS % % % A mV A A/V V V A A nA V mV mV V A V V A V V A V A
Switch Current Limit (SW1, SW2) Switch VCESAT Switch Leakage Current Error Amplifier Transconductance Error Amplifier Voltage Gain VC1, VC2 Switching Threshold VC1, VC2 Clamp Voltage VC1, VC2 Source Current VC1, VC2 Sink Current VC1, VC2 Pin Leakage Current OVP1, OVP2 Overvoltage Threshold Voltage CTRL1, CTRL2 Voltages to Turn Off LED1, 2 Currents CTRL1, CTRL2 Voltages to Turn On LED1, 2 Currents CTRL1, CTRL2 Voltages for Full LED1, 2 Currents CTRL1, CTRL2 Pin Bias Current PWM1, PWM2 Voltage High PWM1, PWM2 Voltage Low PWM1, PWM2 Pin Bias Current SHDN Voltage High SHDN Voltage Low SHDN Pin Bias Current REF Voltage REF Source Current
1
5
VFB1 = VFB2 = 0V VFB1 = VFB2 = 1V VC1 = VC2 = 1V, VPWM1 = VPWM2 = 0V 34
10 38 75
VCTRL1 = VCTRL2 = 3V

150 1.8 20 0.9
30
40 0.4 1 0.4
VPWM1 = VPWM2 = 3V 1.6 VSHDN = 3V IREF = 10A
0.1
1.2 50
20 1.25 80
1.3
Note 1: Absolute maximum ratings are those beyond which the life of a device may be impaired. Note 2: The LT3486E is guaranteed to meet specified performance from 0C to 70C and is designed, characterized and expected to meet these extended temperature limits, but is not tested at -40C and 85C.
Note 3: Current flows out of the pin. Note 4: Guaranteed by design and test correlation, not production tested.
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LT3486 TYPICAL PERFOR A CE CHARACTERISTICS
Switching Waveforms
VSW2 50V/DIV IL2 500mA/DIV VSW1 10V/DIV IL1 1A/DIV 0.5s/DIV VIN = 3.6V 8 LEDs/25mA 2 LEDs/320mA CIRCUIT OF FRONT PAGE APPLICATION
3486 G17
LED Current vs PWM Duty Cycle Wide Dimming Range (1000:1)
100 VIN = 12V 8/8 LEDs PWM FREQ = 100Hz FEEDBACK VOLTAGE (mV) 250
10 ILED (mA)
FEEDBACK VOLTAGE (mV)
1
0.1
0.01 0.01
1 10 0.1 PWM DUTY CYCLE (%)
SHDN Pin Bias Current (CTRL1 = CTRL2 = 3V)
140 VIN = 3.6V SHDN PIN BIAS CURRENT (A) 120 100 80 60 40 20 0 0 4 16 12 8 SHDN PIN VOLTAGE (V) 20 24
3486 G05
OUTPUT CLAMP VOLTAGE (V)
OUTPUT CLAMP VOLTAGE (V)
TA = 50C TA = 25C TA = 100C 36
4
UW
3486 G01
TA = 25C unless otherwise specified.
PWM Dimming Wavforms
ILED 200mA/DIV IL 500mA/DIV PWM 5V/DIV VIN = 12V 0.2ms/DIV 8/8 LEDs PWM FREQ = 1kHz
3486 G18
VFB vs VCTRL
250 VIN = 3.6V TA = 25C 200 200
VFB vs VCTRL (Temperature Variation)
5mV TA = 85C
150
150
TA = -50C
TA = 25C
100
100
50
50
100
0
0
1 0.5 1.5 CONTROL VOLTAGE (V)
0 2
3486 G03
0
1 0.5 1.5 CONTROL VOLTAGE (V)
2
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Open-Circuit Output Clamp Voltage vs Temperature
37 37 VIN = 3.6V RT = 63.4k VOUT2 VOUT1 35 36
Open-Circuit Output Clamp Voltage vs VIN
VIN = 3.6V RT = 63.4k
VOUT1 35 VOUT2
34
34
33 -50
33 -25 75 0 25 50 TEMPERATURE (C) 100 125
2
4
6
8 10 12 14 16 18 20 22 24 VIN (V)
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LT3486 TYPICAL PERFOR A CE CHARACTERISTICS
Input Current with Output 1 and Output 2 Open Circuit
20 TA = 25C RT = 63.4k 1000 OSCILLATOR FREQUENCY (kHz)
INPUT CURRENT (mA)
15
RT (k)
10
5
0
2
4
6
8 10 12 14 16 18 20 22 24 VIN (V)
3486 G08
Oscillator Frequency vs Temperature
10000 OSCILLATOR FREQUENCY (kHz) 12 10 QUIESCENT CURRENT (mA) RT = 22.1k RT = 53.6k 8 6 4 2 0 -25 0 25 50 75 TEMPERATURE (C) 100 125
PWM PIN CURRENT (A)
1000
RT = 309k
100 -50
Switch Current Limit vs Duty Cycle
1800 1700 CURRENT LIMIT (mA) 1600 1500 1400 1300 1200 20 30 40 REF VOLTAGE (V) 1.30
VIN = 3.6V
1.28
REF VOLTAGE (V)
50 60 70 80 DUTY CYCLE (%)
UW
90
TA = 25C unless otherwise specified.
RT vs Oscillator Frequency
1100
Oscillator Frequency vs VIN
RT = 53.6k
1050
100
1000
950
10
900 0 500 1000 1500 2000 OSCILLATOR FREQUENCY (kHz) 2500
3486 G09
2
4
6
8 10 12 14 16 18 20 22 24 VIN (V)
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Quiescent Current vs VIN
1.0
PWM Pin Input Bias Current
VIN = 3.6V
UVLO
0.5
PWM 1
0
PWM 2
-0.5
SHDN = 3V CTRL1 = CTRL2 = 3V
0 2 4 6 8 10 12 14 16 18 20 22 24 VIN (V)
3486 G12
-1.0
0
2
6 8 4 PWM PIN VOLTAGE (V)
10
3486 G13
3486 G11
REF Voltage vs Temperature
1.30
REF Voltage Load Regulation
1.25 1.20 TA = 85C 1.15 1.10 1.05 1.00 TA = 25C TA = -50C
VIN = 3.6V
1.26
1.24
1.22 0.95 1.20 -50 0.90 -25 50 25 0 75 TEMPERATURE (C) 100 125 0 20 40 60 80 100 120 140 160 180 200 REF LOAD CURRENT (A) 3468 G16
VIN = 3.6V TA = 25C
100
3486 G14
3486 G15
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LT3486 PI FU CTIO S
SW1, SW2 (Pins 1, 16): The SW Pins are the Collectors of the Internal Power Transistors. Connect the inductors and Schottky diodes to these pins. Minimize trace area at these pins to minimize EMI. VIN (Pin 2): Input Supply Pin. Must be locally bypassed with an X5R or X7R type ceramic capacitor. OVP1, OVP2 (Pins 3, 14): Output Overvoltage Protection Pins. Connect these pins to the output capacitors. The on-chip voltage detectors monitor the voltages at these pins and limit it to 36V (typ) by turning off the respective switcher and pulling its VC pin low. RT (Pin 4): Timing Resistor to Program the Switching Frequency. The switching frequency can be programmed from 200kHz to 2MHz. VC1, VC2 (Pins 5, 12): The VC Pins are the Outputs of the Internal Error Amplifier. The voltages at these pins control the peak switch currents. Connect a resistor and capacitor compensation network from these pin to ground. FB1, FB2 (Pins 6, 11): The LT3486 regulates the voltage at each feedback pin to 200mV. Connect the cathode of the lowest LED in the string and the feedback resistor (RFB) to the respective feedback pin. The LED current in each string can be programmed by: ILED 200mV/RFB, when VCTRL > 1.8V ILED VCTRL/(5RFB), when VCTRL < 1V CTRL1, CTRL2 (Pins 7, 10): The CTRL pins are used to provide dimming and shutdown control for the individual switching converters. Connecting these to ground shuts down the respective converter. As the voltages on these pins is ramped from 0V to 1.8V, the LED current in each converter ramps from 0 to ILED = (200mV/RFB). Any voltage above 1.8V does not affect the LED current. PWM1, PWM2 (Pins 8, 9): The PWM control pins can be used to extend the dimming range for the individual switching converter. The LED current in each string can be controlled down to A levels by feeding a PWM signal to these pins. When the PWM pin voltage is taken below 0.4V, the respective converter is turned off and its VC pin is disconnected from the internal circuitry. Taking it higher than 0.9V resumes normal operation. Connect these pins to 0.9V supply or higher, if not in use. SHDN (Pin 13): Shutdown Pin for the Device. Connect it to 1.6V or higher to enable device; 0.4V or less to disable device. REF (Pin 15): The internal bandgap reference (1.25V) is available at this pin. Bypass with a 0.1F X5R or X7R ceramic capacitor. Draw no more than 50A from this pin. Exposed Pad (Pin 17): The exposed pad of the package provides an electrical contact to ground and good thermal connection to the printed circuit board (PCB). Solder the exposed pad to the PCB system ground.
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LT3486 BLOCK DIAGRA
OVP1 3
OVERVOLT DETECTION
OVERVOLT DETECTION
OV1
EN1
PWM LOGIC
OSC
RSNS1
A2
A1
VC1 5
OV1
+ - +
REF 1.25V
+ - +
A1
12 VC2
EN1
CONVERTER1 CONTROL
SHDN 80k
20k
START-UP CONTROL
20k
80k
CONVERTER 2 CONTROL
10
9
8
7
6
13
15
11
PWM1 CTRL1
FB1
SHDN
REF
FB2
CTRL2 PWM2
Figure 1. LT3486 Block Diagram
-
EA
0.2V
0.2V
EA
+
-
+
PWM COMP
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SW1 1
RT
4
VIN
2
SW2 16
14 OVP2
CONVERTER1
OSC
OSC
CONVERTER2
DRIVER
Q1 Q2
OV2
+
A3
RAMP GEN
A3
PWM LOGIC
EN2
+
RSNS2 OSC
-
-
+ +
A2 PWM COMP
EN2
OV2
17
3486 F01
EXPOSED PAD
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LT3486 OPERATIO
Main Control Loop The LT3486 uses a constant frequency, current mode control scheme to provide excellent line and load regulation. It incorporates two identical, but fully independent PWM converters. Operation can be best understood by referring to the block diagram in Figure 1. The oscillator, start-up bias and the bandgap reference are shared between the two converters. The control circuitry, power switch, dimming control etc., are all identical for both converters. At power-up, the output capacitors of both converters are charged up to VIN (input supply voltage) via their respective inductor and the Schottky diode. If the SHDN pin is taken above 1.6V, the bandgap reference, start-up bias and the oscillator are turned on. Grounding the SHDN pin shuts down the part. The CTRL1 and CTRL2 pins perform independent dimming and shutdown control for the two converters. Taking the CTRL pins high, enables the respective converters. Connecting these pins to ground, shuts down each converter by pulling their respective VC pin low. Working of the main control loop can be understood by following the operation of converter 1. At the start of each oscillator cycle, the power switch Q1 is turned on. A voltage proportional to the switch current is added to a stabilizing ramp and the resulting sum is fed into the positive terminal of the PWM comparator A2. When this voltage exceeds the level at the negative input of A2, the PWM logic turns off the power switch. The level at the negative input of A2 is set by the error amplifier A1, and is simply an amplified version of the difference between the feedback voltage and the 200mV reference voltage. In this manner, the error amplifier A1 regulates the feedback voltage to 200mV reference voltage. The output of the error amplifier A1 sets the correct peak current level in inductor L1 to keep the output in regulation. The CTRL1 pin voltage is used to adjust the reference voltage. The PWM1, 2 control pins are used to extend the dimming range for the individual converter. The LED current in each string can be controlled down to A levels by feeding a PWM signal to these pins. Refer to the Applications Information section for more detail.
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If only one of the converters is turned on, the other converter will stay off and its output will remain charged up to VIN (input supply voltage). Minimum Output Current The LT3486 can drive an 8-LED string at 4mA LED current without pulse skipping. As current is further reduced, the device may begin skipping pulses. This will result in some low frequency ripple, although the LED current remains regulated on an average basis down to zero. The photo in Figure 2 shows circuit operation with 8 white LEDs at 4mA current driven from 3.6V supply. Peak inductor current is less than 200mA and the regulator operates in discontinuous mode implying that the inductor current reached zero during the discharge phase. After the inductor current reaches zero, the switch pin exhibits ringing due to the LC tank circuit formed by the inductor in combination with switch and diode capacitance. This ringing is not harmful; far less spectral energy is contained in the ringing than in the switch transitions. The ringing can be damped by application of a 300 resistor across the inductors, although this will degrade efficiency.
VOUT2 10mV/DIV VSW2 20V/DIV IL2 200mA/DIV VIN = 3.6V 0.5s/DIV ILED2 = 4mA (8 LEDs) CIRCUIT OF FRONT PAGE APPLICATION
3486 F02
Figure 2. Switching Waveforms
Open-Circuit Protection The LT3486 has internal open-circuit protection for both the converters. Connect the overvoltage protection pins (OVP1, OVP2) to the output of the respective converter. When the LEDs are disconnected from the circuit or fail open, the on-chip voltage detectors monitor the voltages at the OVP1 and OVP2 pins and limits these voltages to 36V (typ) by turning off the respective switcher. The converter will then switch at a very low frequency to minimize the input current. Output voltage and input current during
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LT3486 OPERATIO
output open circuit are shown in the Typical Performance Characteristics graphs. Figure 3a shows the transient response of switcher 1 with the LEDs disconnected from the output. When the LED1 string is disconnected from the output, the voltage at the feedback pin (FB1) drops to 0V. As a result, the error amplifier charges up the VC node to the clamp voltage level of 1.5V (typ). The converter starts switching at peak current limit and ramps up the output voltage. When the output voltage reaches the OVP clamp voltage level of 36V (typ), the LT3486 shuts off the converter by pulling the VC node to ground. The converter then regulates the output voltage at 36V (typ) by switching at a very low frequency. In the event one of the converters has an output opencircuit, its output voltage will be clamped at 36V (typ). However, the other converter will continue functioning properly. The photo in Figure 3b shows circuit operation with converter 1 output open-circuit and converter 2 driving
IL1 1A/DIV VOUT1 20V/DIV
VC1 2V/DIV VIN = 3.6V CIRCUIT OF FRONT PAGE APPLICATION 100s/DIV LED1 DISCONNECTED AT THIS INSTANT
3486 F03a
Figure 3a. Transient Response of Switcher 1 with LED1 Disconnected from the Output
IL1 1A/DIV VOUT1 1V/DIV AC COUPLED IL2 500mA/DIV VIN = 3.6V 2ms/DIV CIRCUIT OF FRONT PAGE APPLICATION LED1 DISCONNECTED
3486 F03b
Figure 3b. Switching Waveforms with Output 1 Open Circuit
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eight LEDs at 25mA. Converter 1 starts switching at a very low frequency, reducing its input current. Soft-Start The LT3486 has a separate internal soft-start circuitry for each converter. Soft-start helps to limit the inrush current during start-up. Soft-start is achieved by clamping the output of the error amplifier during the soft-start period. This limits the peak inductor current and ramps up the output voltage in a controlled manner. The converter enters into soft-start mode whenever the respective CTRL pin is pulled from low to high. Figure 4 shows the start-up waveforms with converter 2 driving eight LEDs at 25mA. The filtered input current, as shown in Figure 4, is well controlled. The soft-start circuit is more effective when driving a smaller number of LEDs. Undervoltage Lockout The LT3486 has an undervoltage lockout circuit which shuts down both the converters when the input voltage drops below 2.1V (typ). This prevents the converter to operate in an erratic mode when powered from low supply voltages. Overtemperature Protection The maximum allowable junction temperature for LT3486 is 125C. In normal operation, the IC's junction temperature should be kept below 125C at an ambient temperature of 85C or less. If the junction temperature exceeds 150C, the internal thermal shutdown circuitry kicks in and turns-off both the converters. The converters will remain off until the die temperature falls below 150C.
IIN 200mA/DIV VOUT2 10V/DIV VFB2 200mV/DIV CTRL2 5V/DIV VIN = 3.6V 0.5ms/DIV 8 LEDs, 25mA CIRCUIT OF FRONT PAGE APPLICATION
3486 F04
Figure 4. Start-Up Waveforms
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LT3486 APPLICATIO S I FOR ATIO
Duty Cycle The duty cycle for a step-up converter is given by: D= where: VOUT = Output voltage VD = Schottky forward voltage drop VCESAT = Saturation voltage of the switch VIN = Input battery voltage The maximum duty cycle achievable for LT3486 is 96% (typ) when running at 1MHz switching frequency. It increases to 98% (typ) when run at 200kHz and drops to 90% (typ) at 2MHz. Always ensure that the converter is not duty-cycle limited when powering the LEDs at a given switching frequency. Setting the Switching Frequency The LT3486 uses a constant frequency architecture that can be programmed over a 200kHz to 2MHz range with a single external timing resistor from the RT pin to ground. The nominal voltage on the RT pin is 0.54V, and the current that flows into the timing resistor is used to charge and discharge an internal oscillator capacitor. A graph for selecting the value of RT for a given operating frequency is shown in the Figure 5. VOUT + VD - VIN VOUT + VD - VCESAT
1000
RT (k)
100
10
0
500 1000 1500 2000 OSCILLATOR FREQUENCY (kHz)
2500
3486 G09
Figure 5. Timing Resistor (RT) Value
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Operating Frequency Selection The choice of operating frequency is determined by several factors. There is a tradeoff between efficiency and component size. Higher switching frequency allows the use of smaller inductors albeit at the cost of increased switching losses and decreased efficiency. Another consideration is the maximum duty cycle achievable. In certain applications the converter needs to operate at the maximum duty cycle in order to light up the maximum number of LEDs. The LT3486 has a fixed oscillator off-time and a variable on-time. As a result, the maximum duty cycle increases as the switching frequency is decreased. The circuit of Figure 6a is operated with different values of timing resistor (RT). RT is chosen so as to run the converters at 800kHz (RT = 63.4k), 1.25MHz (RT = 39.1k) and 2MHz (RT = 21.5k). The CTRL pins are used to provide dimming for the respective LED strings. The efficiency comparison for different RT values is shown in Figure 6b.
5V CIN 10F D2 L1 10H SW1 OVP1 25mA CTRL1 OFF ON REF SHDN PWM1 FB1 VC1 2.8k 8.06 4.7nF CIN: 10V, X7R COUT1, COUT2: 35V, X5R D1, D2: ZETEX ZHCS400 L1, L2: TOKO D53LC TYPE A RT RT LT3486 CTRL2 REF PWM2 FB2 VC2 2.8k 4.7nF 8.06
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D1 COUT1 2.2F L2 10H VIN SW2 OVP2
COUT2 2.2F
25mA 1.25V CREF 0.1F
Figure 6a. 5V to 8/8 White LEDs
LT3486 APPLICATIO S I FOR ATIO
90 80 RT = 63.4k EFFICIENCY (%) 70 RT = 21.5k 60 50 40 30 0 5 10 15 LED CURRENT (mA) 20 25
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VIN = 5V 8/8 LEDs
RT = 39.1k
Figure 6b. Efficiency Comparison for Different RT Resistors
Inductor Selection The choice of the inductor will depend on the selection of switching frequency of LT3486. The switching frequency can be programmed from 200kHz to 2MHz. Higher switching frequency allows the use of smaller inductors albeit at the cost of increased switching losses. The inductor current ripple (IL), neglecting the drop across the Schottky diode and the switch, is given by: IL = where: L = Inductor f = Operating frequency VIN(MIN) = Minimum input voltage VOUT(MAX) = Maximum output voltage The IL is typically set to 20% to 40% of the maximum inductor current. The inductor should have a saturation current rating greater than the peak inductor current required for the application. Also, ensure that the inductor has a low DCR (copper wire resistance) to minimize I2R power losses. Recommended inductor values range from 4.7H to 22H. VIN(MIN) * (VOUT (MAX) - VIN(MIN) ) VOUT (MAX) * f * L
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Several inductors that work well with the LT3486 are listed in Table 1. Consult each manufacturer for more detailed information and for their entire selection of related parts.
Table 1. Recommended Inductors
L (H) 15 22 4.7 6.8 10 10 15 10 15 MAX DCR () 0.150 0.190 0.045 0.068 0.090 0.098 0.149 0.048 0.145 CURRENT RATING (A) 1.40 1.20 2.49 2.01 1.77 1.22 0.94 1.30 0.97 PART LQH55DN150M LQH55DN220M A915AY-4R7M A915AY-6R8M A915AY-100M A918CY-100M A918CY-150M CDRH4D28-100 CDRH5D18-150 VENDOR Murata (814) 237-1431 www.murata.com Toko (847) 297-0070 www.toko.com Sumida (847) 956-0666 www.sumida.com
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Capacitor Selection The small size of ceramic capacitors make them ideal for LT3486 applications. Use only X5R and X7R types because they retain their capacitance over wider voltage and temperature ranges than other types such as Y5V or Z5U. A 4.7F or larger input capacitor is sufficient for most applications. Always use a capacitor with sufficient voltage rating. Table 2 shows a list of several ceramic capacitor manufacturers. Consult the manufacturers for detailed information on their entire selection of ceramic parts.
Table 2. Ceramic Capacitor Manufacturers
Taiyo Yuden AVX Murata (408) 573-4150 www.t-yuden.com (803) 448-9411 www.avxcorp.com (714) 852-2001 www.murata.com
Diode Selection Schottky diodes with their low forward voltage drop and fast reverse recovery, are the ideal choices for LT3486 applications. The diode conducts current only during the switch off time. The peak reverse voltage that the diode must withstand is equal to the regulator output voltage.
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LT3486 APPLICATIO S I FOR ATIO
The average forward current in normal operation is equal to the output current, and the peak current is equal to the peak inductor current. A Schottky diode rated at 1A is sufficient for most LT3486 applications. Some recommended Schottky diodes are listed in Table 3.
Table 3. Recommended Schottky Diodes
PART NUMBER MBR0530 MBRM120E ZLLS400 ZLLS1000 ZHCS400 ZHCS1000 VR (V) 30 20 40 40 40 40 IAVG (A) 0.5 1 0.4 1 0.4 1 MANUFACTURER On Semiconductor www.onsemi.com Zetex www.zetex.com
When the LT3486 is set up for PWM dimming operation, choose a Schottky diode with low reverse leakage current. During PWM dimming operation, the output capacitor is required to hold up the charge in the PWM "off" period. A low reverse leakage Schottky helps in that mode of operation. The Zetex ZLLS400 and ZLLS1000 are available in a small surface mount package and are a good fit for this application. MOSFET Selection The power MOSFET used in LT3486 applications with wide dimming range requirements should be chosen based on the maximum drain-source voltage. The maximum drain current ID(MAX) and gate-to-source voltages should also be considered when choosing the FET. Choose a MOSFET with maximum VDS (drain source) voltage greater than the output clamp voltage i.e., 36V (typ). Fairchild Semiconductor's FDN5630 (60V, 1.7A N-channel FET) is a good fit for most LT3486 applications. For dimming low current LEDs (~25mA), Fairchild 2N7002 is a good alternative. Programming LED Current The current in each LED string can be set independently by the choice of resistors RFB1 and RFB2 respectively (see front page application). The feedback reference is 200mV. In order to have accurate LED current, precision resistors are preferred (1% is recommended).
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200mV ILED1 200mV RFB2 = ILED2 RFB1 =
Table 4. RFB Value Selection
ILED (mA) 5 10 15 20 25 RFB () 40.2 20.0 13.3 10.0 8.06
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Most low power white LEDs are driven at maximum currents of 15mA to 25mA. The LT3486 can be used to power high power LEDs as well. Refer to the Typical Applications for more detail. Dimming Control The dimming of the two LED strings can be controlled independently by modulating the respective CTRL and PWM pins. There are two ways to control the intensity of the LEDs. Adjusting the LED Current Value Controlling the current flowing through the LEDs controls the intensity of the LEDs.This is the easiest way to control the intensity of the LEDs. The LED forward current can be controlled by modulating the DC voltage at the respective CRTL pin. The PWM pins are not in use when appying this scheme. They must be connected to a 0.9V supply or higher. The DC voltage at the CTRL pin can be modulated in two ways. (a) Using a DC Voltage Source For some applications, the preferred method of brightness control is a variable DC voltage fed to the CTRL pins. The CTRL1, CTRL2 pin voltage can be modulated to set the dimming of the respective LED string. As the voltage on the CTRL1, CTRL2 pin increases from 0V to 1.8V, the LED current increases from 0 to ILED. As the CTRL1, CTRL2 pin voltage increases beyond 1.8V, it has no effect on the LED current.
3486f
LT3486 APPLICATIO S I FOR ATIO
The LED current can be set by: ILED (200mV/RFB), when VCTRL > 1.8V ILED (VCTRL/5 * RFB), when VCTRL < 1V Feedback voltage variation versus control voltage is given in the Typical Performance Characteristics graphs. (b) Using a Filtered PWM Signal A variable duty cycle PWM can be used to control the brightness of the LED string. The PWM signal is filtered (Figure 7) by an RC network and fed to the CTRL1, CTRL2 pins. The corner frequency of R1, C1 should be much lower than the frequency of the PWM signal. R1 needs to be much smaller than the internal impedance in the CTRL pins, which is 100k.
PWM 10kHz TYP R1 10k C1 1F LT3486 CTRL1,2
3486 F07
Figure 7. Dimming Control Using a Filtered PWM Signal
12V (TYP) 9V TO 15V L1 10H COUT1 2.2F D1 5V C1 1F CIN 10F
L2 10H D2 COUT2 2.2F
SW1 LUXEON LEDs LXCL-PWF1 OVP1 VIN OFF ON 100mA PWM1 FB1 VC1
DIMMING INPUT 1
VIN
SW2 OVP2 CTRL2 VIN CREF 0.1F LUXEON LEDs LXCL-PWF1 ILED 200mA/DIV IL 500mA/DIV PWM 5V/DIV VIN = 12V 0.2ms/DIV 8/8 LEDs PWM FREQ = 1kHz PWM FREQ 1kHz RFB2 2
3486 TA10a 3486 G18
CTRL1 SHDN LT3486
REF PWM2 FB2
RT
VC2 22pF 3.65k
DIMMING INPUT 2
3.65k 21.5k Q1 2.2nF
PWM FREQ 1kHz 100k
2.2nF
RFB1 COUT1, COUT2: 35V, X5R OR X7R D1, D2: ZETEX ZLLS1000 2 CIN: 25V, X5R OR X7R L1, L2: TOKO D53LC (TYPE A) Q1, Q2: FAIRCHILD FDN5630 C1: 10V, X5R OR X7R CREF: 6.3V, X5R OR X7R
Figure 8a. 12V to 8/8 White LEDs
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Pulse-Width Modulation (PWM) Adjusting the forward current flowing in the LEDs changes the intensity of the LEDs, as explained in the previous section. However, a change in forward current also changes the color of the LEDs. The chromaticity of the LEDs changes with the change in forward current. Many applications cannot tolerate any shift in the color of the LEDs. Controlling the intensity of the LEDs via applying a PWM signal allows dimming of the LEDs without changing the color. Dimming the LEDs via a PWM signal essentially involves turning the LEDs on and off at the PWM frequency. The human eye has a limit of 60 frames per second. By increasing the PWM frequency to say, 80Hz, the eye can be deceived into believing that the pulsed light source is continously on. Additionally by modulating the duty cycle (amount of "on-time"), the intensity of the LEDs can be controlled. The color of the LEDs remains unchanged in this scheme since the LED current value is either zero or a constant value. Figure 8(a) shows a 12V to 8/8 white LED driver. The PWM dimming control method requires an external NMOS tied to the cathode of the lowest LED in the string, as shown in
100mA Q2
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Figure 8b. PWM Dimming Waveforms
100k
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LT3486 APPLICATIO S I FOR ATIO
the figure. A PWM logic input is applied to the gate of the NMOS and the PWM pin of the LT3486. When the PWM input is taken high, the LEDs are connected to the RFB resistor and a current ILED = 200mV/RFB flows through the LEDs. When the PWM input is taken low, the LEDs are disconnected and turn off. The low PWM input applied to the LT3486 ensures that the respective converter turns off and its VC pin goes high impedance. This ensures that the capacitor connected to the VC pin retains its voltage which in turn allows the LEDs to turn on faster, as shown in Figure 8(b). The CTRL pin is not used to modulate the LED current in the scheme. It can be connected to a supply voltage greater than 1.8V. The dimming control pins (PWM1, PWM2) can be used to extend the dimming range for the individual switching converters. The LED current can be controlled down to A levels by feeding a PWM signal with frequencies in the range of 80Hz to 50kHz. The LED current can be controlled by PWM frequencies above 50kHz but the controllable current decreases with increasing frequency. Pulling the PWM pins below 0.4V disables the respective switcher. Taking it higher than 0.9V resumes normal operation. Connect these pins to 0.9V or higher if not in use.
100
10 LED CURRENT (mA) VC1 1 VIN
0.1 PWM FREQ = 100Hz PWM FREQ = 1kHz PWM FREQ = 25kHz 1 10 0.1 PWM DUTY CYCLE (%) 100
0.01 0.01
3486 F09
Figure 9. LED Current Variation vs PWM Duty Cycle
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Figure 9 shows the LED current variation vs PWM duty cycle. The LED current is controlled by applying a PWM of frequency 100Hz, 1kHz and 25kHz to the circuit of Figure 8a. As seen in the curves, the LED string is able to get a wide (1000:1) dimming range with PWM frequency of 100Hz. The dimming range decreases as PWM frequency goes up. Board Layout Consideration As with all switching regulators, careful attention must be paid to the PCB board layout and component placement. To prevent electromagnetic interference (EMI) problems, proper layout of high frequency switching paths is essential. Minimize the length and area of all traces connected to the switching node pins (SW1 and SW2). Keep the feedback pins (FB1 and FB2) away from the switching nodes. The DFN and FE packages both have an exposed paddle that must be connected to the system ground. The ground connection for the feedback resistors should be tied directly to the ground plane and not shared with any other component, except the RT resistor, ensuring a clean, noise-free connection. Recommended component placement for the DFN package is shown in the Figure 10.
VIAs TO VIN PLANE VOUT1 OVP1 RT VOUT2 REF OVP2 SHDN VIN SW1
1 2 3 4 5 6 16 15 14
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SW2
VC2
17
13 12 11 10 9
FB1 LED1
7
CTRL1
8
CTRL2
LED2
FB2
PWM1 VIAs TO VIN PLANE
VIN
PWM2 VIAs TO GROUND PLANE
3486 F10
Figure 10. Recommended Layout for LT3486
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LT3486 TYPICAL APPLICATIO S
Li-Ion Cell Powered Driver for Camera Flash and LCD Backlighting
VIN 3V TO 5V CIN 10mF D1 COUT1 2.2mF SW1 OVP1 320mA DIMMING 1 OFF ON CTRL1 SHDN PWM1 FB1 5V OFF ON 0V 100k RFB1 0.62W 0.1mF Q1 VC1 63.4k RT LT3486 L1 10mH VIN L2 10mH SW2 OVP2 25mA CTRL2 REF PWM2 FB2 VC2 2.8k 4.7nF RFB2 8.06W
3486 TA02a
LED1 AOT3218
EFFICIENCY (%)
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D2 COUT2 2.2mF
DIMMING 2 CREF 0.1mF
CIN: 6.3V, X5R OR X7R DIELECTRIC COUT1, COUT2: 35V, X5R OR X7R D1: ZETEX ZHCS1000 D2: ZETEX ZHCS400
L1, L2: TOKO D53LC (TYPE A) Q1: FAIRCHILD FDN5630
Efficiency vs VIN
90 MOVIE MODE ILED1 = 175mA 85 FLASH MODE ILED1 = 320mA
80
75
70 8 LEDS/25mA 3 3.2 3.4 3.6 VIN (V) 3.8 4 4.2
65
3486 TA01b
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LT3486 TYPICAL APPLICATIO S
1 Li-Ion Cell to 8/8 White LEDs
3V TO 5V CIN 10F D1 COUT1 2.2F SW1 8 LEDs VIN OFF ON 25mA PWM1 FB1 VC1 2.8k PWM1 100Hz 5V Q1 4.7nF 63.4k RT OVP1 CTRL1 SHDN LT3486 L1 10H VIN L2 10H SW2 OVP2 CTRL2 REF PWM2 FB2 VC2 2.8k 4.7nF Q2 PWM2 100Hz 8.06 100k VIN CREF 0.1F 25mA 8 LEDs
100k
LED Current and Efficiency vs PWM Duty Cycle
85 80 75 EFFICIENCY (%) EFFICIENCY 70 65 LED CURRENT 60 55 50 0 20 40 60 80 PWM DUTY CYCLE (%)
3486 TA05b
VIN = 3.6V 8/8 LEDs
20 15 10 5 0 100
LED CURRENT (mA)
LED CURRENT 20mA/DIV
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D2 COUT2 2.2F
8.06
COUT1, COUT2: 35V, X5R OR X7R CIN: 10V, X5R OR X7R
D1, D2: ZETEX ZLLS400 L1, L2: TOKO D53LC (TYPE A) Q1, Q2: FAIRCHILD 2N7002
3486 TA05A
Wide (250:1) Dimming Range (LED Current 0.1mA to 25mA)
100 VIN = 3.6V 8/8 LEDs PWM FREQ = 100Hz 10
35 30 25 LED CURRENT (mA)
1
0.10
0.01 0.1 1 10 DUTY CYCLE (%) 100
3486 TA05d
PWM Dimming Waveforms
IL 200mA/DIV PWM 5V/DIV VIN = 3.6V CTRL1 = 3.6V 8 LEDs/25mA PWM FREQ = 100Hz 2ms/DIV
3486 TA05c
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LT3486 TYPICAL APPLICATIO S
5V to 16/16 White LEDs
D5 C3 1mF 16 LEDs C1 0.1mF L1 15mH L2 15mH C2 0.1mF 5V CIN 1mF D3 D4 D6 C4 1mF 16 LEDs
25mA
PWM FREQ 200Hz 100k
LED Current and Efficiency vs PWM Duty Cycle
85 80 75 EFFICIENCY (%) EFFICIENCY 70 65 LED CURRENT 60 55 50 0 20 40 60 80 PWM DUTY CYCLE (%)
3486 TA08b
VIN = 5V 16/16 LEDs
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COUT1 2.2mF
D1 SW1 OVP1 VIN CTRL1 SHDN PWM1 FB1 VC1 4.02k 63.4k RT LT3486 VIN SW2 OVP2 CTRL2 REF PWM2 FB2 VC2 4.02k
D2
COUT2 2.2mF
VIN CREF 0.1mF
25mA
OFF ON
22pF
Q1
4.7nF
4.7nF
Q2 100k
PWM FREQ 200Hz
8.06W CIN: 6.3V, X5R OR X7R COUT1, COUT2: 35V, X5R OR X7R C1-C4: 50V, X5R OR X7R CREF: 6.3V, X5R OR X7R
8.06W D1, D2: ZETEX ZLLS400 D3-D6: PHILIPS BAV99W L1, L2: TOKO D53LC (TYPE A) Q1, Q2: FAIRCHILD 2N7002
3486 TA08a
PWM Dimming Waveforms
35 30 25 20 15 10 5 0 100 LED CURRENT (mA) ILED 50mA/DIV
IL 500mA/DIV
PWM 5V/DIV L = 15H PWM FREQ = 200Hz 1ms/DIV
3486 TA08c
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LT3486 PACKAGE DESCRIPTIO U
DHC Package 16-Lead Plastic DFN (5mm x 3mm)
(Reference LTC DWG # 05-08-1706)
0.65 0.05 3.50 0.05 PACKAGE OUTLINE 0.25 0.05 0.50 BSC 4.40 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 5.00 0.10 (2 SIDES) R = 0.20 TYP R = 0.115 TYP 9 16 0.40 0.10 3.00 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) 8 0.200 REF 0.75 0.05 4.40 0.10 (2 SIDES) BOTTOM VIEW--EXPOSED PAD NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WJED-1) IN JEDEC PACKAGE OUTLINE MO-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 1 0.25 0.05 0.50 BSC 1.65 0.10 (2 SIDES) PIN 1 NOTCH
(DHC16) DFN 1103
1.65 0.05 2.20 0.05 (2 SIDES)
0.00 - 0.05
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LT3486 PACKAGE DESCRIPTIO U
FE Package 16-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1663)
Exposed Pad Variation BB
3.58 (.141)
4.90 - 5.10* (.193 - .201) 3.58 (.141) 16 1514 13 12 1110 9
6.60 0.10 4.50 0.10
SEE NOTE 4
2.94 (.116) 0.45 0.05 1.05 0.10 0.65 BSC 2.94 6.40 (.116) (.252) BSC
RECOMMENDED SOLDER PAD LAYOUT
12345678 1.10 (.0433) MAX
0 - 8
4.30 - 4.50* (.169 - .177)
0.25 REF
0.09 - 0.20 (.0035 - .0079)
0.50 - 0.75 (.020 - .030)
0.65 (.0256) BSC
NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 3. DRAWING NOT TO SCALE
0.195 - 0.30 (.0077 - .0118) TYP
0.05 - 0.15 (.002 - .006)
FE16 (BB) TSSOP 0204
4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE
3486f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LT3486 TYPICAL APPLICATIO
12V to 8/8 White LEDs
12V (TYP) 9V TO 15V L1 10H COUT1 2.2F D1 5V C1 1F CIN 10F
SW1 LUXEON LEDs LXCL-PWF1 OVP1 VIN OFF ON 100mA PWM1 FB1 VC1
DIMMING INPUT 1
EFFICIENCY (%)
CTRL1 SHDN LT3486
3.65k 21.5k Q1 2.2nF
PWM FREQ 1kHz 100k
RFB1 2
COUT1, COUT2: 35V, X5R OR X7R D1, D2: ZETEX ZLLS1000 L1, L2: TOKO D53LC (TYPE A) CIN: 25V, X5R OR X7R Q1, Q2: FAIRCHILD FDN5630 C1: 10V, X5R OR X7R CREF: 6.3V, X5R OR X7R
RELATED PARTS
PART NUMBER LT1618 LT1932 LT1937 LTC3200 LTC3200-5 LTC3201 LTC3202 LTC3205 DESCRIPTION Constant Current, Constant Voltage 1.24MHz, High Efficiency Boost Regulator Constant Current, 1.2MHz, High Efficiency White LED Boost Regulator Constant Current, 1.2MHz, High Efficiency White LED Boost Regulator Low Noise, 2MHz, Regulated Charge Pump White LED Driver MS Package Low Noise, 2MHz, Regulated Charge Pump White LED Driver ThinSOT Package Low Noise, 1.7MHz, Regulated Charge Pump White LED Driver MS Package Low Noise, 1.5MHz, Regulated Charge Pump White LED Driver MS Package High Efficiency, Multidisplay LED Controller COMMENTS Up to 16 White LEDs, VIN: 1.6V to 18V, VOUT(MAX) = 34V, IQ = 1.8mA, ISD < 1A, MS Package Up to 8 White LEDs, VIN: 1V to 10V, VOUT(MAX) = 34V, IQ = 1.2mA, ISD < 1A, ThinSOTTM Package Up to 4 White LEDs, VIN: 2.5V to 10V, VOUT(MAX) = 34V, IQ = 1.9mA, ISD < 1A, ThinSOT, SC70 Packages Up to 6 White LEDs, VIN: 2.7V to 4.5V, IQ = 8mA, ISD < 1A, Up to 6 White LEDs, VIN: 2.7V to 4.5V, IQ = 8mA, ISD < 1A, Up to 6 White LEDs, VIN: 2.7V to 4.5V, IQ = 6.5mA, ISD < 1A, Up to 8 White LEDs, VIN: 2.7V to 4.5V, IQ = 5mA, ISD < 1A, Up to 4 (Main), 2 (Sub) and RGB, VIN: 2.8V to 4.5V, IQ = 50A, ISD < 1A, QFN-24 Package Up to Six White LEDs, VIN: 2.7V to 16V, VOUT(MAX) = 34V, IQ = 1.9mA, ISD < 1A, ThinSOT Package Drives Up to 20 LEDs, VIN: 2.7V to 24V, VOUT(MAX) = 40V, IQ = 5mA, ISD < 16A, DFN Package
LT3465/LT3465A Constant Current, 1.2MHz/2.7MHz, High Efficiency White LED Boost Regulator with Integrated Schottky Diode LT3466 Dual Full Function White LED Boost Regulator with Integrated Schottky Diode
20 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2005
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L2 10H D2 COUT2 2.2F
LED Current and Efficiency vs PWM Duty Cycle
90 EFFICIENCY 85 100 LED CURRENT (mA) 80 LED CURRENT 75 70 65
3.65k 2.2nF Q2
DIMMING INPUT 2
120
VIN
SW2 OVP2 CTRL2 REF PWM2 FB2 VIN CREF 0.1F LUXEON LEDs LXCL-PWF1
80
60 40 20 VIN = 12V 8/8 LEDs 0 100
3486 TA10b
100mA
RT
VC2 22pF
60
PWM FREQ 1kHz
0
20
40 60 80 PWM DUTY CYCLE (%)
RFB2 2
3486 TA10a
100k
3486f LT/TP 0705 500 * PRINTED IN USA

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