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19-3135; Rev 0; 1/04
KIT ATION EVALU E AILABL AV
White LED Camera-Flash Boost Converter
General Description Features
Supports Up to Five LEDs for Strobe or Flash Four Operational Modes Strobe: Up to 300mA Precharge: With POK Indicator Movie: Up to 100mA Shutdown: 0.01A (typ) Quiescent Current Input Current Limiting 1A (MAX1583X) 500mA (MAX1583Y) 250mA (MAX1583Z) Small External Components 2.6V to 5.5V Input Range 24V Output Overvoltage Protection 80% Efficient (PLED / PIN) Movie Mode Thermal-Shutdown Protection 10-Pin 3mm x 3mm TDFN Package
MAX1583
The MAX1583 white LED boost converter drives up to five white LEDs with a constant current to provide camera flash/strobe in cell phones, PDAs, DSCs, and other hand-held devices. The MAX1583 includes a 24V boost converter and a high-voltage LDO current regulator for high efficiency and long battery life. Two logic inputs control four modes of operation: shutdown mode (0.5A max), movie mode for high-efficiency continuous lighting (programmable up to 100mA), precharge mode for charging a reservoir capacitor to 24V while the LEDs are off (POK output indicates a full reservoir capacitor), and strobe mode for firing the flash during an exposure with a regulated current programmable up to 300mA. The MAX1583X, MAX1583Y, and MAX1583Z offer high, medium, and low current limits, respectively, to allow tradeoff between reservoir capacitor size and peak input current. The MAX1583 is available in a 10-pin 3mm x 3mm TDFN package (0.8mm max height).
Applications
Camera Flashes/Strobes Cell Phones and Smart Phones PDAs and Digital Still Cameras
PART MAX1583XETB MAX1583YETB MAX1583ZETB
Ordering Information
TEMP RANGE -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 10 TDFN 3mm x 3mm 10 TDFN 3mm x 3mm 10 TDFN 3mm x 3mm
Typical Operating Circuit
PART
VIN 2.6V TO 5.5V
Selector Guide
CURRENT LIMIT 1A 500mA 250mA TOP MARK ACJ ACK ACL MAX1583XETB MAX1583YETB MAX1583ZETB
IN GND POK EN1 EN2 STB MOV
LX
MAX1583
ILED UP TO 300mA OUT
Pin Configuration
TOP VIEW
GND
LED EN1 0 0 1 1 EN2 0 1 0 1 SHUTDOWN PRECHARGE MOVIE STROBE
1 2 3 4 5
TDFN (3mm x 3mm)
10 9
LX LED OUT EN2 EN1
IN MOV STB POK
MAX1583
8 7 6
________________________________________________________________ Maxim Integrated Products
1
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White LED Camera-Flash Boost Converter MAX1583
ABSOLUTE MAXIMUM RATINGS
IN, EN1, EN2, POK to GND ......................................-0.3V to +6V LX, OUT to GND .....................................................-0.3V to +30V STB, MOV to GND .......................................-0.3V to (VIN + 0.3V) LED to GND..............................................-0.3V to (VOUT + 0.3V) ILX ...................................................................................1.2ARMS Continuous Power Dissipation (TA = +70C) 10-Pin 3mm x 3mm TDFN (derate 24.4mW/C above +70C) .............................1951mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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 in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = VEN1 = 3.0V, VEN2 = 0V, VOUT = 20V, COUT = 10F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C. Note 1)
PARAMETER Supply Voltage Undervoltage-Lockout Threshold OUT Input Bias Current Quiescent-Current Precharge Mode Quiescent-Current Shutdown Mode Output Overvoltage-Lockout Threshold LED Regulation Voltage Threshold LED Input Leakage Current MOV, STB Regulation Voltage Current-Source Multiplier in Movie Mode Current-Source Accuracy, Movie Mode MOV Current-Source Dropout Voltage Current-Source Multiplier in Strobe Mode Current-Source Accuracy, Strobe Mode STB Current-Source Dropout Voltage Current Limit POK Low Voltage POK Leakage ILED / IMOV, IMOV up to 300A RMOV = 2k, VLED = 0.5V ILED = 25mA, RMOV = 2k ILED / ISTB, ISTB up to 300A RSTB = 2k, VLED = 3.0V ILED = 250mA, RSTB = 2k MAX1583X MAX1583Y MAX1583Z ISINK = 1mA TA = +25C TA = +85C 800 400 200 -10 -7 LX switching, LEDs off LX not switching, LEDs off EN1 = EN2 = GND TA = +25C TA = +85C 22.5 0.5 VIN rising, hysteresis = 40mV (typ) CONDITIONS MIN 2.6 2.10 4 2.38 10 2 0.32 0.01 0.1 24 0.6 0.01 0.1 600 100 1 0.1 1000 1.5 0.9 1000 500 250 0.05 0.01 0.1 1200 600 300 0.1 1 V A mA +10 +7 25.5 0.7 1 0.5 TYP MAX 5.5 2.55 15 UNITS V V A mA A V V A mV A/A % V A/A % V
VOUT rising, precharge or movie mode, hysteresis = 500mV (typ) VLED rising, movie mode Precharge mode TA = +25C TA = +85C
2
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White LED Camera-Flash Boost Converter
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VEN1 = 3.0V, VEN2 = 0V, VOUT = 20V, COUT = 10F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C. Note 1)
PARAMETER EN1 and EN2 Input High Threshold EN1 and EN2 Input Low Threshold EN1 and EN2 Input Leakage LX On-Resistance LX Leakage Operating Frequency Maximum Duty Cycle Minimum Duty Cycle CONDITIONS VIN = 2.6V to 5.5V VIN = 2.6V to 5.5V EN_ = IN ILX = 200mA VLX = 28V TA = 0C to +85C TA = -40C to +85C Switching Pulse skipping TA = +25C TA = +85C 0.8 0.75 90 94 0 TA = +25C TA = +85C 0.01 0.1 1.3 0.01 0.1 1.0 1.2 1.25 2.25 5 MIN 1.6 0.6 1 TYP MAX UNITS V V A A MHz % %
MAX1583
Note 1: All units are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed by design.
Typical Operating Characteristics
(VIN = 3.3V, CRES = 10F, MAX1583Y, 4 LEDs in a 2 x 2 array, TA = +25C, unless otherwise noted.)
EFFICIENCY vs. INPUT VOLTAGE (MOVIE MODE)
MAX1583 toc01
MAXIMUM BOOST OUTPUT CURRENT vs. INPUT VOLTAGE (MAX1583X)
MAX1583 toc02
MAXIMUM BOOST OUTPUT CURRENT vs. INPUT VOLTAGE (MAX1583Y)
A: 1 LED B: 2 LEDs C: 3 LEDs D: 4 LEDs
MAX1583 toc03
90 C 80 70 EFFICIENCY (%) 60 B
700 600 500 IOUT (mA)
A: 1 LED B: 2 LEDs C: 3 LEDs D: 4 LEDs
600 500 400
A
A
50 40 30
400 B 300 200 C D
IOUT (mA)
A
300 B 200 C 100 D 0
20 10 0
A: MAX1583X B: MAX1583Y C: MAX1583Z 3.0 3.3 3.6
100 ILOAD = 30mA 0 3.9 4.2 2.5 3.0 3.5 4.0 VIN (V) 4.5 5.0
5.5
2.5
3.0
3.5
4.0 VIN (V)
4.5
5.0
5.5
INPUT VOLTAGE (V)
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3
White LED Camera-Flash Boost Converter MAX1583
Typical Operating Characteristics (continued)
(VIN = 3.3V, CRES = 10F, MAX1583Y, 4 LEDs in a 2 x 2 array, TA = +25C, unless otherwise noted.)
MAXIMUM BOOST OUTPUT CURRENT vs. INPUT VOLTAGE (MAX1583Z)
400 350 300 IOUT (mA) 250 200 150 100 50 0 2.5 3.0 3.5 4.0 VIN (V) 4.5 5.0 B C D 5.5 A: 1 LED B: 2 LEDs C: 3 LEDs D: 4 LEDs
MAX1583 toc04
STROBE-MODE LED CURRENT vs. STB RESISTANCE
MAX1583 toc05
MOVIE-MODE LED CURRENT vs. MOV RESISTANCE
MAX1583 toc06
450
350 300 LED CURRENT (mA) 250 200 150 100 50 0 2 4 6 8 10
120 100 LED CURRENT (mA) 80 60 40 20 0
A
12
0
2
4
6 RMOV (k)
8
10
12
RSTB (k)
STROBE STANDBY-MODE INPUT CURRENT vs. INPUT VOLTAGE (PRECHARGE DONE)
MAX1583 toc07
SWITCHING WAVEFORMS IN MOVIE MODE
MAX1583 toc08
2500
2000 INPUT CURRENT (A)
MAX1583Z MAX1583Y
IL
200mA/div
1500
1000
VOUT AC-COUPLED
50mV/div
500 MAX1583X 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VLX
5V/div
4s/div
INPUT VOLTAGE (V)
SWITCHING WAVEFORMS DURING PRECHARGE MODE
MAX1583 toc09
SWITCHING WAVEFORMS IN STANDBY MODE
MAX1583 toc10
IL
500mA/div
IL
500mA/div
VOUT AC-COUPLED
500mV/div
VOUT AC-COUPLED
500mV/div
VLX
10V/div
VLX
10V/div
1s/div
4ms/div
4
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White LED Camera-Flash Boost Converter MAX1583
Typical Operating Characteristics (continued)
(VIN = 3.3V, CRES = 10F, MAX1583Y, 4 LEDs in a 2 x 2 array, TA = +25C, unless otherwise noted.)
SWITCHING WAVEFORMS IN STROBE MODE
MAX1583 toc11
PRECHARGE-CYCLE WAVEFORMS (MAX1583X)
MAX1583 toc12
PRECHARGE-CYCLE WAVEFORMS (MAX1583Y)
MAX1583 toc13
VPOK
5V/div 100mA/div
VPOK
5V/div
VPOK
5V/div
ILED IIN VOUT 10V/div 1A/div IIN 500mA/div
10V/div 500mA/div IIN 20s/div 500s/div VOUT VOUT 10V/div
500s/div
PRECHARGE-CYCLE WAVEFORMS (MAX1583Z)
MAX1583 toc14
STROBE-PULSE WAVEFORMS (MAX1583X)
MAX1583 toc15
VPOK
5V/div IIN 1A/div
ILED IIN 200mA/div VOUT 10V/div VOUT 500s/div 10ms/div
100mA/div
10V/div
STROBE-PULSE WAVEFORMS (MAX1583Y)
MAX1583 toc16
STROBE-PULSE WAVEFORMS (MAX1583Z)
MAX1583 toc17
IIN
500mA/div
IIN
200mA/div
ILED ILED 100mA/div 10V/div VOUT CRES = 100F 10ms/div 10ms/div VOUT CRES = 200F
100mA/div
10V/div
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5
White LED Camera-Flash Boost Converter MAX1583
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 -- NAME GND IN MOV STB POK EN1 EN2 OUT LED LX EP Ground. Connect to exposed paddle. Input Voltage Supply. Input voltage range is 2.6V to 5.5V. Bypass IN to GND with a 4.7F ceramic capacitor. Movie Current-Set Input. Connect a resistor from MOV to GND to set the LED current for movie-mode operation. RMOV = 60 / ILED (where RMOV > 600k). Strobe Current-Set Input. Connect a resistor from STB to GND to set the LED current for strobe-mode operation. RSTB = 600 / ILED (where RSTB > 2k). Power-OK Output. Pulled to GND during precharge mode. POK goes high impedance once VOUT reaches 24V. Enable 1. EN1 and EN2 are digital inputs that determine the operational mode of the MAX1583. See Table 1. Enable 2. EN1 and EN2 are digital inputs that determine the operational mode of the MAX1583. See Table 1. Output-Voltage Sense Input. The boost-converter circuit in the MAX1583 is disabled once VOUT is greater than 24V. When VOUT falls below 23.5V, the converter is enabled. LED Return Input. Connect to the cathode of the series LEDs. Regulates to 0.6V in movie mode. LED is high impedance during shutdown and precharge mode. Inductor Connection. Drain of the internal power MOSFET. Connect to the switched side of the inductor. LX is high impedance during shutdown. Exposed Paddle. Connect to the circuit ground plane. FUNCTION
Functional Diagram
CURRENT-LIMIT COMPARATOR CURRENT-LIMIT THRESHOLD
MAX1583
IN REFERENCE
THERMAL LIMIT
LX BOOST-CONVERTER CONTROL N POK
POK CIRCUITRY MOVIE-MODE FEEDBACK COMPARATOR
N OUT
POK COMPARATOR
EN1 EN2 MOV
ENABLE DECODE
CURRENT REGULATOR STB
N LED
GND
6
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White LED Camera-Flash Boost Converter
Detailed Description
The MAX1583 provides power and control for up to five white LEDs. The MAX1583 consists of a gated oscillator, a 24V boost converter, and an LED current-regulation circuit, and operates from 2.6V to 5.5V input supply voltages. The MAX1583 operates in one of four userselectable modes (Table 1). The precharge mode charges the output capacitor to 24V for quick transients to strobe mode. The POK output indicates the output has reached its regulation value of 24V and is ready for a strobe pulse. In movie mode, the LED current is regulated at a user-selectable level for constant lighting. Strobe mode regulates the LED current to a user-selectable high-intensity level for still picture use. When the MAX1583 is not in use, it can be put in shutdown mode, reducing the input current to 0.01A (typ).
Current Regulator
The MAX1583 controls the brightness by regulating the current through the external LEDs to a user-selectable level. In movie mode, the current into LED is regulated to 100 times the current set by the MOV resistor, RMOV. In strobe mode, the current into LED is regulated to 1000 times the current set by the STB resistor, RSTB.
MAX1583
Precharge Mode
Drive EN1 low and EN2 high to enable precharge mode. In this mode, the boost converter switches continuously until the output capacitor is charged to 24V. Once VOUT reaches 24V, POK goes high impedance and the MAX1583 does not switch again until VOUT falls below 23.5V. This results in a 500mV ripple on the output during this mode. LED is high impedance in precharge mode; therefore, the external LEDs are off.
Table 1. Enable Inputs
EN1 0 0 1 1 EN2 0 1 0 1 MODE Shutdown Precharge Movie Strobe
POK Output
An open-drain, power-OK output (POK) is low until V OUT reaches 24V. Once the threshold is reached, POK is latched in a high-impedance state. The latch is reset in strobe, precharge, or movie mode.
Strobe Mode
Drive EN1 and EN2 high to enable strobe mode. In this mode, the boost converter switches continuously to supply maximum current for the LEDs unless limited by overvoltage lockout. The current through the LEDs is regulated to 1000 times the current set by the STB resistor. See the Adjusting the LED Current section for details on setting the strobe-mode current. The time duration of the strobe mode must be set using external circuitry or software.
Boost Converter
The heart of the MAX1583 is a gated oscillator boost converter that is used to supply the LED current. The boost converter is active when the feedback input voltage (VLED) is below the regulation threshold (0.6V) and VOUT is below the overvoltage-lockout threshold (24V). During switching cycles, the 94% (typ) duty cycle, 1MHz oscillator switches an internal power MOSFET. On the rising edge of each clock cycle, the MOSFET is turned on, ramping up current and storing energy in the external inductor. On the falling edge of the oscillator, the MOSFET is turned off, allowing the energy stored in the inductor to be transferred to the output. Under normal operation, the MOSFET turns on or off only at the beginning or end of the oscillator cycle. This ensures there are no short-duration pulses. Exceeding the current limit or thermal limit, or pulling EN1 and EN2 low, immediately turns the MOSFET off.
Movie Mode
Drive EN1 high and EN2 low to enable movie mode. In this mode, the boost converter switches as necessary to maintain VLED at 0.6V, and the current regulator regulates the current through LED to 100 times the current set by the MOV resistor. See the Adjusting the LED Current section for details on setting the moviemode current.
Shutdown Mode
Drive EN1 and EN2 low to place the MAX1583 into a low-power shutdown mode. LED is high impedance during shutdown, eliminating the DC conduction path that exists in the typical boost topology.
_______________________________________________________________________________________
7
White LED Camera-Flash Boost Converter MAX1583
VIN 2.6V TO 5.5V L1 4.7H D1
2 R3 100k POWER-OK C1 22F 1 5 6 7 MODE CONTROL R1 6.04k 1% R2 3.01k 1%
IN GND POK EN1 EN2
LX
10
MAX1583X
C2 10F D2, D3, D4 WHITE LEDs OUT 8 C3 0.1F
4
STB LED
9
3 MOV
Figure 1. Typical Application Circuit
Design Procedure
Adjusting the LED Current
The LED current in the strobe and movie modes is programmable using external resistors. To set the LED current during strobe mode, connect a resistor (RSTB) from STB to GND. VSTB is regulated to 0.6V and the current sourced by STB is mirrored through LED with a gain of 1000. RSTB is calculated as: RSTB = 600 / ILED(DESIRED) To set the LED current during movie mode, connect a resistor (RMOV) from MOV to GND. VMOV is regulated to 0.6V and the current sourced by MOV is mirrored through LED with a gain of 100. RMOV is calculated as: RMOV = 60 / ILED(DESIRED)
nect a reservoir capacitor from OUT to GND to provide the extra LED current. The value of this capacitor is calculated as: (I -I ) x t STROBE CRES = LED BOOST 24 V - (n x VF ) where: ILED is the desired strobe current, IBOOST is the maximum current from the boost converter obtained from the Typical Operating Characteristics, tSTROBE is the time duration of the strobe, n is the number of LEDs, and VF is the forward voltage of the LEDs. For example, assume a minimum input voltage of 3.2V with the MAX1583Y (500mA current limit). The required strobe current is 100mA for 30ms through two series LEDs with a 4V forward voltage. The reservoir capacitor is determined as follows: I BOOST = 75mA from the Typical Operating Characteristics. CRES = (100mA - 75mA) x 30ms 24 V - (2 x 4 V) = 25mA x 30ms 16V = 47F
Reservoir Capacitance vs. Current Limit
During strobe mode, the current demands on the boost converter to maintain the desired LED strobe current may cause the MAX1583 to reach the preset current limit. The MAX1583 is available with three factory-preset current limits: 250mA, 500mA, and 1A. If the current limit is reached, the internal MOSFET terminates its ON cycle early, causing the output current to drop. See the Typical Operating Characteristics for the Maximum Boost IOUT vs. VIN for each current limit. If the required strobe current exceeds the maximum boost IOUT, con8
_______________________________________________________________________________________
White LED Camera-Flash Boost Converter
Input-Capacitor Selection
Bypass the input to GND using a ceramic capacitor. Place the capacitor as close to the IC as possible. The exact value of the input capacitor is not critical. The typical value for the input capacitor is 22F when using the MAX1583X, 10F when using the MAX1583Y, and 4F when using the MAX1583Z. Using these values reduces the input ripple to an acceptable level.
Applications Information
PC Board Layout
Due to fast-switching waveforms and high-current paths, careful PC board layout is required. An evaluation kit (MAX1583EVKIT) is available as an example to speed design. When laying out a board, minimize trace lengths between the IC and the inductor, the diode, the input capacitor, and the output capacitor. Keep traces short, direct, and wide. The IN bypass capacitor should be placed as close to the IC as possible. GND should be connected directly to the exposed paddle underneath the IC. The ground connections of CIN and COUT should be as close together as possible. The traces from IN to the inductor and from the Schottky diode to the LEDs can be longer.
MAX1583
Output-Capacitor Selection
The output capacitance required depends on the required LED current and the time duration of the pulse in strobe mode. See the Reservoir Capacitance vs. Current Limit section for details on determining this capacitance value. Note that the output capacitor must be rated for 25V or greater. In addition to the reservoir capacitor, bypass the output with a 0.1F, 25V capacitor from OUT to LED.
Inductor Selection
The recommended inductor values for use with the MAX1583 range from 4.7H to 47H. With input voltages near 5V, a larger value of inductance can be more efficient. To prevent core saturation, ensure that the inductor-saturation current rating exceeds the current limit of the MAX1583 (250mA, 500mA, or 1A).
Chip Information
TRANSISTOR COUNT: 1395 PROCESS: BiCMOS
Schottky-Diode Selection
The MAX1583 requires a high-speed rectification diode (D1) for optimum performance. A Schottky diode is recommended due to its fast recovery time and low forward-voltage drop. Ensure that the diode's average and peak current ratings exceed the average output current and the current limit (ILIMIT) of the MAX1583 (250mA, 500mA, or 1A). In addition, the diode's reverse breakdown voltage must exceed VOUT. The RMS diode current is calculated as: IDIODE(RMS) ILED(MAX) x ILIMIT
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9
White LED Camera-Flash Boost Converter MAX1583
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
L D A A2
PIN 1 ID
D2
1
N
1
b
PIN 1 INDEX AREA
C0.35 [(N/2)-1] x e REF. e
E
DETAIL A
E2
A1
k
C L
C L
L e A e
L
SEMICONDUCTOR
PROPRIETARY INFORMATION TITLE:
DALLAS
PACKAGE OUTLINE, 6, 8 & 10L, TDFN, EXPOSED PAD, 3x3x0.80 mm
NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY
APPROVAL DOCUMENT CONTROL NO. REV.
21-0137
D
1 2
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40
0.25 MIN. 0.20 REF.
PACKAGE VARIATIONS PKG. CODE T633-1 T833-1 T1033-1 N 6 8 10 D2 1.500.10 1.500.10 1.500.10 E2 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.65 BSC 0.50 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEED-3 b 0.400.05 0.300.05 0.250.05 [(N/2)-1] x e 1.90 REF 1.95 REF 2.00 REF
SEMICONDUCTOR
PROPRIETARY INFORMATION TITLE:
DALLAS
PACKAGE OUTLINE, 6, 8 & 10L, TDFN, EXPOSED PAD, 3x3x0.80 mm
APPROVAL DOCUMENT CONTROL NO. REV.
21-0137
D
2 2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
6, 8, &10L, DFN THIN.EPS

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