19-3461; Rev 0; 11/04
VAILABLE
TION KIT A
EVALUA
1.2A White LED Regulating Charge Pump for
Camera Flashes and Movie Lights
General Description
The MAX1577Y/MAX1577Z charge pumps drive white
LEDs, including camera strobes, with regulated current
up to 1.2A (guaranteed to 800mA). The very low open-
loop output resistance allows high flash brightness,
even from a low battery input voltage. The adaptive
1x/2x regulating charge-pump operation provides high
efficiency (up to 92%) while in movie mode or back-
lighting. Fast (1MHz) switching allows the use of tiny
external components.
The MAX1577Y/MAX1577Z use an external resistor to
set the full-scale LED current. Two enable inputs (EN1
and EN2) provide simple on/off control and LED current
of 20%, 33%, or 100% full scale. If there is less than
24mV across the external resistor, the output voltage is
regulated. The MAX1577Z has fixed 5.1V output-volt-
age regulation, while the MAX1577Y has logic-con-
trolled output voltage of 3.4V, 4.6V, or 5.1V for
backlighting, keyboard, and RGB applications.
The MAX1577Y/MAX1577Z are available in an 8-pin,
3mm x 3mm TDFN package (0.8mm max height).
Features
♦
Up to 1.2A Output Drive Capability (800mA
Guaranteed)
♦
Up to 92% P
LED
/ P
BATT
Efficiency for Movie
Mode
♦
Flexible Brightness Control
Two-Bit Logic for 100%, 33%, 20%, and Off
PWM for 20% to 100%
♦
3% Current Regulation Over Line and
Temperature
♦
Current or Voltage Regulation for Flash and
Backlighting (MAX1577Y)
♦
Current Regulation for Flash (MAX1577Z)
♦
Low Ripple and EMI
♦
2.7V to 5.5V Supply Voltage Range
♦
Soft-Start Limits Inrush Current
♦
Output-Voltage Regulation Mode
♦
Thermal-Shutdown Protection
♦
8-Pin 3mm x 3mm TDFN Package
MAX1577Y/MAX1577Z
Applications
White LED Flashes, Strobes, and Movie Lights
LCD Backlighting
Camera Phones, Cell Phones, and Smart Phones
PDAs, Digital Cameras, and Camcorders
Ordering Information
PART
MAX1577YETA
TEMP RANGE
-40°C to +85°C
PIN-
PACKAGE
8 TDFN
(T833-2)
8 TDFN
(T833-2)
TOP
MARK
AMG
MAX1577ZETA
-40°C to +85°C
AMQ
Typical Operating Circuit
1µF OR 2.2µF
OUT
Pin Configuration
GND
5
4
EN2
TOP VIEW
CN
5.3V OVP
OUT
10µF
CS
7
2
CP
CP
2.7V TO 5.5V
IN
4.7µF
GND
UP TO 1.2A
8
MAX1577Z
100%,
33%, 20%,
AND
SHUTDOWN
EN1
EN2
CS
V
OUT
- (300mV OR
100mV OR 60mV)
1
EN1
MAX1577Y
MAX1577Z
TDFN
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
CN
IN
6
3
1.2A White LED Regulating Charge Pump for
Camera Flashes and Movie Lights
MAX1577Y/MAX1577Z
ABSOLUTE MAXIMUM RATINGS
IN, OUT, EN1, EN2 to GND ...................................-0.3V to +6.0V
OUT to GND During Shutdown....................-0.3V to (V
IN
+ 0.3V)
OUT to CS .............................................................-0.6V to +0.6V
CS to GND................................................-0.3V to (V
OUT
+ 0.3V)
CN to GND...................................................-0.3V to (V
IN
+ 0.3V)
CP to GND .....-0.3V to the Greater of (V
OUT
+ 1V) or (V
IN
+ 1V)
OUT Short Circuit to GND ..........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
8-Pin TDFN (derate 18.2mW/°C above +70°C) ..........1455mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated 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
(V
IN
= 3.6V, circuit of Figure 2, EN1 = EN2 = IN, R
CS
= 60Ω, C
IN
= 4.7µF, C1 = 2.2µF, C
OUT
= 10µF, T
A
= -40°C to +85°C, unless
otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
IN Operating Voltage
Undervoltage-Lockout Threshold
Undervoltage-Lockout Hysteresis
Supply Current
Shutdown Supply Current
Soft-Start Time
OUT Overvoltage Protection
MAX1577Z, T
A
= +25°C,
I
OUT
= 100mA
OUT Voltage Regulation Mode
MAX1577Y, T
A
= +25°C,
I
OUT
= 100mA
CS Voltage-Mode Threshold
(V
OUT
- V
CS
)
EN1 = GND, EN2 = IN
CS Regulation Voltage
(V
OUT
- V
CS
)
CS Threshold Accuracy
Maximum OUT Current
Open-Loop OUT Resistance
OUT Internal Pulldown in
Shutdown
Switching Frequency
EN1 = IN, EN2 = GND
EN1 = EN2 = IN
T
A
= +25°C
V
IN
= 2.7V to 5.5V, TA = -40°C to +85°C
V
LED
= 4.1V, EN1 = EN2 = IN
1x LDO mode
2x mode, V
IN
= 3.4V
EN1 = EN2 = GND
0.80
V
IN
= 3.1V
V
IN
= 3.4V
-2
-3
600
800
900
1200
0.6
2
5
1.0
1.25
3
EN1 or EN2 = IN
EN1 = GND, EN2 = IN
EN1 = IN, EN2 = GND
EN1 = EN2 = IN
4.95
3.17
4.40
4.95
1MHz switching, no load
1x LDO mode, no switching
EN1 = EN2 = GND
T
A
= +25°C
T
A
= +85°C
V
IN
rising
CONDITIONS
MIN
2.7
2.3
2.45
35
5
0.225
0.01
0.2
0.5
5.3
5.10
3.40
4.60
5.10
24
60
100
300
±0.5
+2
+3
%
mA
Ω
kΩ
MHz
mV
5.25
3.60
4.80
5.25
mV
V
0.3
1
TYP
MAX
5.5
2.6
UNITS
V
V
mV
mA
µA
ms
V
2
_______________________________________________________________________________________
1.2A White LED Regulating Charge Pump for
Camera Flashes and Movie Lights
MAX1577Y/MAX1577Z
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3.6V, circuit of Figure 2, EN1 = EN2 = IN, R
CS
= 60Ω, C
IN
= 4.7µF, C1 = 2.2µF, C
OUT
= 10µF, T
A
= -40°C to +85°C, unless
otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
EN_ Logic-High Voltage
EN_ Logic-Low Voltage
Logic Input Current
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
V
IN
= 4.2V to 5.5V
V
IN
= 2.7V to 4.2V
V
IN
= 2.7V to 5.5V
V
EN
_ = 0V or 5.5V
T
J
rising
T
A
= +25°C
T
A
= +85°C
0.02
0.02
+160
20
CONDITIONS
MIN
1.6
1.4
0.4
1
TYP
MAX
UNITS
V
V
µA
°C
°C
Note 1:
Limits are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by design.
Typical Operating Characteristics
(V
IN
= 3.6V, circuit of Figure 2, R
CS
= 0.27Ω, Luxeon LXCL-PWF1 LED, T
A
= +25°C, unless otherwise noted.)
LED CURRENT vs. SUPPLY VOLTAGE
MAX1577 toc01
EFFICIENCY vs. SUPPLY VOLTAGE
MAX1577 toc02
BATTERY CURRENT vs. SUPPLY VOLTAGE
R
CS
= 0.27Ω
2000
BATTERY CURRENT (mA)
1100mA AT 3.78V
F
1500
370mA AT 3.33V
F
220mA AT 3.15V
F
500
MAX1577 toc03
1200
1000
1100mA AT 3.78V
F
LED CURRENT (mA)
800
600
400
200
R
CS
= 0.27Ω
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
220mA AT 3.15V
F
370mA AT 3.33V
F
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
220mA AT 3.15V
F
370mA AT 3.33V
F
1100mA AT 3.78V
F
R
CS
= 0.27Ω
2500
1000
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
5.5
SUPPLY VOLTAGE (V)
LED CURRENT vs. SUPPLY VOLTAGE
MAX1577 toc04
EFFICIENCY vs. SUPPLY VOLTAGE
90
80
EFFICIENCY (%)
70
60
50
40
30
20
150mA AT 3.06V
F
250mA AT 3.21V
F
770mA AT 3.66V
F
MAX1577 toc05
BATTERY CURRENT vs. SUPPLY VOLTAGE
1600
BATTERY CURRENT (mA)
1400
1200
1000
800
600
400
200
250mA AT 3.21V
F
150mA AT 3.06V
F
770mA AT 3.66V
F
R
CS
= 0.39Ω
MAX1577 toc06
900
800
700
LED CURRENT (mA)
600
500
400
300
200
100
0
2.7
3.1
3.5
3.9
R
CS
= 0.39Ω
150mA AT 3.06V
F
4.3
4.7
5.1
250mA AT 3.21V
F
770mA AT 3.66V
F
100
1800
10
0
5.5
2.7
3.1
3.5
3.9
4.3
SUPPLY VOLTAGE (V)
R
CS
= 0.39Ω
4.7
5.1
5.5
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
3
1.2A White LED Regulating Charge Pump for
Camera Flashes and Movie Lights
MAX1577Y/MAX1577Z
Typical Operating Characteristics (continued)
(V
IN
= 3.6V, circuit of Figure 2, R
CS
= 0.27Ω, Luxeon LXCL-PWF1 LED, T
A
= +25°C, unless otherwise noted.)
LED CURRENT vs. TEMPERATURE
MAX1577 toc07
LED CURRENT vs. R
CS
MAX1577 toc08
TYPICAL OPERATING WAVEFORMS
IN 1x MODE
MAX1577 toc09
225
1.2
1.0
EN1 AND EN2 HIGH
LED CURRENT (A)
0.8
0.6
EN1 HIGH, EN2 LOW
0.4
EN1 LOW, EN2 HIGH
220
LED CURRENT (mA)
V
IN
50mV/div
(AC-COUPLED)
215
V
OUT
50mV/div
(AC-COUPLED)
50mV/div
(AC-COUPLED)
210
205
R
CS
= 0.27Ω
EN1 LOW
EN2 HIGH
-40
-15
10
35
60
85
V
CS
0.2
0
0.2
0.4
0.6
R
CS
(Ω)
0.8
1.0
400ns/div
TEMPERATURE (°C)
200
TYPICAL OPERATING WAVEFORMS
IN 2x MODE
MAX1577 toc10
STARTUP AND SHUTDOWN RESPONSE
MAX1577 toc11
V
IN
50mV/div
(AC-COUPLED)
V
EN1,
V
EN2
2V/div
V
OUT
50mV/div
(AC-COUPLED)
V
LED
2V/div
0V
V
CS
50mV/div
(AC-COUPLED)
I
LED
500mA/div
0mA
400ns/div
400µs/div
LED CURRENT vs. PWM DUTY CYCLE
MAX1577 toc12
EFFICIENCY vs. SUPPLY VOLTAGE
WITH PWM DIMMING
70
25%
60
EFFICIENCY (%)
MAX1577 toc13
DIMMING RESPONSE
MAX1577 toc14
1200
1000
LED CURRENT (mA)
800
600
400
200
0
0
20
40
60
80
R
CS
= 0.27Ω
EN1 PWM
EN2 HIGH
80
V
EN1
2V/div
50
40
50%
30
20
10
0
2.7
3.1
3.5
3.9
4.3
R
CS
= 0.27Ω
EN1 PWM
EN2 HIGH
4.7
5.1
5.5
I
LED
75%
V
LED
2V/div
0V
500mA/div
0mA
100µs/div
100
DUTY CYCLE (%)
SUPPLY VOLTAGE (V)
4
_______________________________________________________________________________________
1.2A White LED Regulating Charge Pump for
Camera Flashes and Movie Lights
Pin Description
PIN
1
2
3
4
5
6
7
8
—
NAME
EN1
CP
CN
EN2
GND
IN
CS
OUT
EP
Control Logic Input (see Table 1)
Transfer Capacitor Positive Connection. Connect a 1µF capacitor (or 2.2µF for I
OUT
> 600mA) from
CP to CN.
Transfer Capacitor Negative Connection. Connect a 1µF capacitor (or 2.2µF for I
OUT
> 600mA) from
CP to CN.
Control Logic Input (see Table 1)
Ground
Input Supply Voltage. Connect IN to a battery or supply voltage from 2.7V to 5.5V. Connect a 4.7µF
ceramic capacitor from IN to GND.
Current-Sense Input. Connect a current-sense resistor from OUT to CS to set the output current.
Connect the anodes of the LEDs to CS and the cathodes to GND.
Output. Connect a 10µF ceramic capacitor from OUT to GND. In shutdown, OUT is pulled to GND
with an internal 5kΩ resistor.
Exposed Pad. Connect the exposed pad to GND directly under the IC.
FUNCTION
MAX1577Y/MAX1577Z
Table 1. Enable, Dimming, Voltage Mode, and Overvoltage Protection
EN1
0
0
1
1
EN2
0
1
0
1
DIMMING LEVEL
Shutdown
20% Current
33% Current
100% Current
CS THRESHOLD
(V
OUT
- V
CS
)
—
60mV
100mV
300mV
VOLTAGE MODE
MAX1577Z
—
5.10V
5.10V
5.10V
MAX1577Y
—
3.40V
4.60V
5.10V
MAX1577Z
—
5.30V
5.30V
5.30V
OVP
MAX1577Y
—
5.15V
5.17V
5.30V
Note:
A “0” indicates EN_ is logic low or connected to GND. A “1” indicates EN_ is logic high or connected to IN.
_______________________________________________________________________________________
5
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