MAX1707ETG-T [MAXIM]
Liquid Crystal Driver, PQCC24, 4MM X 4MM , TQFN-24;
| 型号： | MAX1707ETG-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Liquid Crystal Driver, PQCC24, 4MM X 4MM , TQFN-24 闪光灯 泵 |
| 文件： | 总15页 (文件大小：793K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3744; Rev 0; 7/05
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
General Description
Features
The MAX1707 provides complete light management for
main display backlight, subdisplay backlight (or RGB
indicator), and white LED camera flash with regulated
constant current up to 610mA total. By utilizing adap-
tive 1x/1.5x/2x charge-pump modes and very-low-
dropout current regulators, it achieves high efficiency
over the full 1-cell Li+ battery input voltage range. The
1MHz fixed-frequency switching allows for tiny external
components while the regulation scheme is optimized
to ensure low EMI and low input ripple. An integrated
derating function protects the LEDs from overheating
during high ambient temperatures.
♦ Guaranteed 610mA Continuous Drive Capability
4 LEDs at 30mA Each for Main Display
3 LEDs at 30mA Each for Sub or RGB
400mA Total for Flash
♦ 2-Wire I2C Serial Port
5-Bit (32-Step) Linear Dimming
32k Colors
Ramp-Up/Down Rates
♦ 92% Peak/83% Avg Efficiency (P
/P
)
LED BATT
♦ Adaptive 1x/1.5x/2x Mode Switchover
♦ 0.3% (typ) LED Current Accuracy and Matching
♦ Low Input Ripple and EMI
The MAX1707 features an internally trimmed reference
†
to set the maximum LED current. An I2C serial port is
used for on/off control and setting the LED currents in
32 linear steps. When using the RGB indicator, the I2C
port provides 32k colors and programmable ramp-
up/down rates. The camera flash may be turned on/off
by the I2C port or a separate digital logic input.
♦ Low 0.1µA Shutdown Current
♦ Output Overvoltage Protection
♦ Thermal Derating Function Protects LEDs
♦ 24-Pin 4mm x 4mm Thin QFN Package
Applications
Ordering Information
Cell Phones and Smartphones
PDAs, Digital Cameras, Camcorders
Displays with Up to 11 LEDs
PKG
PIN-
PART
TEMP RANGE
CODE
PACKAGE
24 Thin QFN
4mm x 4mm
†
MAX1707ETG -40°C to +85°C
T2444-4
Purchase of I2C components from Maxim Integrated Products,
Inc., or one of its sublicensed Associated Companies, conveys
a license under the Philips I2C Patent Rights to use these com-
ponents in an I2C system, provided that the system conforms to
the I2C Standard Specification as defined by Philips.
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
1µF
1µF
INPUT
2.7V TO 5.5V
OUTPUT
UP TO 610mA
C1P
C1N
C2P
C2N
OUT
IN
FLASH
MAIN
SUB OR RGB
PIN
10µF
4.7µF
GND
M1
MAX1707
M2
M3
M4
S1
V
V
DD
LOGIC
0.1µF
S2
2
S3
I C PORT
ON/OFF AND
BRIGHTNESS
SCK
SDA
STB
F1
F2
F3
F4
STROBE
ON/OFF
PGND
________________________________________________________________ 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.
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
ABSOLUTE MAXIMUM RATINGS
Continuous Power Dissipation (T = +70°C)
A
V
, IN, PIN, SCK, SDA, STB, OUT to GND .........-0.3V to +6.0V
DD
24-Pin Thin QFN (derate 20.8mW/°C above +70°C)...1666mW
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
M_, S_, F_ to GND....................................-0.3V to (V
C1N, C2N to GND .......................................-0.3V to (V + 0.3V)
+ 0.3V)
OUT
IN
IN
C1P, C2P to GND ..-0.3V to greater of (V
+ 0.3V) or (V + 0.3V)
OUT
PGND to GND .......................................................-0.3V to +0.3V
OUT Short Circuit to GND ..........................................Continuous
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 = V
= V
= 3.6V, V
= V = 0V, temperature derating disabled, T = -40°C to +85°C, typical values are at T =
PGND A A
IN
PIN
DD
GND
+25°C, unless otherwise noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
2.7
TYP
MAX
5.5
UNIT
IN Operating Voltage
V
V
V
Operating Range
2.7
5.5
DD
Undervoltage-Lockout Threshold
Undervoltage-Lockout Hysteresis
Output Overvoltage-Protection Threshold
V
V
rising or falling
2.25
2.60
V
IN
50
5.00
4.0
0.35
0.7
0.8
0.1
0.1
0.5
1.0
1.5
mV
V
rising
4.75
5.25
6.5
OUT
1.5x or 2x mode
10% setting, 1x mode, flash off
IN + PIN No-Load Supply Current
IN + PIN Shutdown Supply Current
mA
µA
µA
T
T
T
T
= +25°C
= +85°C
= +25°C
= +85°C
5
1
A
A
A
A
All LEDs off, STB = SDA =
SCK = V , I C ready
DD
2
All LEDs off, STB = SDA =
SCK = V , I C ready
DD
V
Quiescent Current
DD
2
Startup into 1x mode
Startup into 1.5x mode
Startup into 2x mode
Soft-Start Time
ms
LED Current Derating Function Start
Temperature
Temperature derating enabled
= +40°C to +85°C, temperature derating
+40
°C
%/°C
%
T
A
LED Current Derating Function Slope
-1.7
0.3
enabled
Default current setting, T = +25°C
-2
-5
+2
+5
A
LED Current SUB Output Accuracy
(Note 2)
Default current setting, T = -40°C to +85°C
A
LED Current FLASH and MAIN Output
Accuracy
Default current setting (Note 2)
-5
0.3
+5
%
M_, S_
F_
28.5
95
30.0
100
40
Maximum M_, S_, F_ Sink Current
mA
M_, S_
90
90
LED Dropout Voltage
100% LED setting (Note 3)
F_
mV
mV
mV
40
1.5x and 2x Mode Regulation Voltage
150
1x to 1.5x and 1.5x to 2x Mode Transition
Threshold
V
, V , V falling
M_ S_ F_
100
2
_______________________________________________________________________________________
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
ELECTRICAL CHARACTERISTICS (continued)
(V = V
= V
= 3.6V, V
= V = 0V, temperature derating disabled, T = -40°C to +85°C, typical values are at T =
PGND A A
IN
PIN
DD
GND
+25°C, unless otherwise noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
150
0.01
0.1
5
MAX
UNIT
Input Voltage Mode Transition Hysteresis
mV
T
T
= +25°C
= +85°C
1
A
A
All LEDs off, STB =
M_, S_, F_ Leakage in Shutdown
µA
V
DD
OUT Pulldown Resistance in Shutdown
Maximum OUT Current
All LEDs off, STB = V
kΩ
DD
V
≥ 3.2V, V
= 3.9V
OUT
610
mA
IN
1x mode (V - V
) / I
0.5
1.5
2.0
1
2.5
3.5
4.1
IN
OUT
OUT
OUT
Open-Loop OUT Resistance
Switching Frequency
1.5x mode (1.5 x V - V
) / I
Ω
IN
OUT
2x mode (2 x V - V
IN
) / I
OUT
OUT
MHz
9
SDA = 111xxx00
SDA = 111xxx01
SDA = 111xxx10
SDA = 111xxx11
2
18
2
S1, S2, S3 (RGB) Full-Scale Ramp Time
µs
19
2
20
2
Logic-Input High Voltage
Logic-Input Low Voltage
V
V
= 2.7V to 5.5V
= 2.7V to 5.5V
V
/ 2
V
V
DD
DD
DD
0.4
1
T
T
= +25°C
= +85°C
0.01
0.1
A
A
V
5.5V
= 0V or V
=
IH
IL
Logic-Input Current
µA
SDA Output Low Voltage
I
= 3mA
0.03
0.4
V
kHz
µs
µs
µs
µs
µs
µs
ns
µs
°C
°C
SDA
2
I C Clock Frequency
400
Bus-Free Time Between START and STOP
Hold Time Repeated START Condition
SCK Low Period
t
t
t
t
t
t
t
t
1.3
0.6
1.3
0.6
0.6
0
BUF
0.1
0.2
HD_STA
LOW
SCK High Period
0.2
HIGH
Setup Time Repeated START Condition
SDA Hold Time
0.1
SU_STA
HD_DAT
SU_DAT
SU_STO
-0.01
50
SDA Setup Time
100
0.6
Setup Time for STOP Condition
Thermal Shutdown
0.1
+160
20
Thermal-Shutdown Hysteresis
Note 1: All devices are 100% production tested at T = +25°C. Limits over the operating temperature range are guaranteed
A
by design.
Note 2: LED current specification includes both accuracy and matching tolerance.
Note 3: Dropout voltage is defined as the M2 or F3 to GND voltage at which current into M2 or F3 drops 10% from the value at 0.2V.
All other current regulators are tested functionally by the accuracy test and guaranteed for low dropout by design.
_______________________________________________________________________________________
3
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
EFFICIENCY vs. SUPPLY VOLTAGE
INPUT CURRENT vs. SUPPLY VOLTAGE
DRIVING LUMILEDS LXCL-PWF1 FLASH
INPUT CURRENT vs. SUPPLY VOLTAGE
DRIVING 4 MAIN LEDs AND RGB LEDs
DRIVING 4 MAIN LEDs
100
900
800
700
600
500
400
300
200
100
0
450
400
350
300
250
200
150
100
50
SUPPLY VOLTAGE FALLING
30mA/LED
90
80
70
60
400mA
30mA/LED
15mA/LED
50
40
30
20
10
0
15mA/LED
1.9mA/LED
1.9mA/LED
200mA
100mA
SUPPLY VOLTAGE FALLING
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
SUPPLY VOLTAGE (V)
5.1 5.5
2.7 3.1 3.5 3.9 4.3 4.7
SUPPLY VOLTAGE (V)
5.1 5.5
SUPPLY VOLTAGE (V)
LED CURRENT MATCHING
vs. SUPPLY VOLTAGE
(MAIN AND RGB AT FULL CURRENT)
INPUT CURRENT vs. SUPPLY VOLTAGE
DRIVING 4 MAIN LEDs
INPUT CURRENT vs. SUPPLY VOLTAGE
DRIVING RGB LEDs
31.2
30.9
30.6
30.3
30.0
29.7
29.4
29.1
450
400
350
300
250
200
150
100
50
450
400
350
300
250
200
150
100
50
SUPPLY VOLTAGE FALLING
SUPPLY VOLTAGE FALLING
RED
V = 1.9V
F
4 WHITE
V = 3.4V
F
30mA/LED
30mA/LED
15mA/LED
1.9mA/LED
BLUE
V = 4.2V
GREEN
V = 2V
15mA/LED
1.9mA/LED
F
F
28.8
0
0
2.7 3.1 3.5 3.9 4.3 4.7
SUPPLY VOLTAGE (V)
5.1 5.5
2.7 3.1 3.5 3.9 4.3 4.7
SUPPLY VOLTAGE (V)
5.1 5.5
2.7 3.1 3.5 3.9 4.3 4.7
SUPPLY VOLTAGE (V)
5.1 5.5
LED CURRENT MATCHING
vs. SUPPLY VOLTAGE
(MAIN AND RGB AT 1.9mA/LED)
LED CURRENT vs. TEMPERATURE
1.96
1.94
1.92
1.90
1.88
1.86
1.84
1.82
30
25
20
15
10
5
THERMAL DERATING OFF
RED
V = 1.7V
F
4 WHITE
V = 2.9V
F
4 MAIN OR 4 FLASH LEDs
THERMAL DERATING ON
GREEN
V = 1.9V
BLUE
V = 3.4V
F
F
1.80
0
2.7 3.1 3.5 3.9 4.3 4.7
SUPPLY VOLTAGE (V)
5.1 5.5
-40
-15
10
35
60
85
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
OPERATING WAVEFORMS 1X MODE
OPERATING WAVEFORMS 1.5X MODE
MAX1707 toc09
MAX1707 toc10
50mV/div
50mV/div
V
V
OUT
OUT
(AC-COUPLED)
(AC-COUPLED)
V
IN
I
IN
50mV/div
(AC-COUPLED)
V
IN
I
IN
50mV/div
(AC-COUPLED)
100mA/div
0
100mA/div
0
1µs/div
1µs/div
MAIN BACKLIGHT STARTUP WAVEFORM
OPERATING WAVEFORMS 2X MODE
MAX1707 toc12
MAX1707 toc11
5V/div
1V/div
V
V
SDA
50mV/div
(AC-COUPLED)
V
OUT
OUT
50mV/div
(AC-COUPLED)
100mA/div
V
I
IN
IN
0
I
IN
200mA/div
0
0
1ms/div
1µs/div
MAIN STARTUP WITH RGB ALREADY ON
FLASH STARTUP WAVEFORM
MAX1707 toc13
MAX1707 toc14
5V/div
1V/div
5V/div
1V/div
V
V
V
V
SDA
OUT
SDA
OUT
0
0
I
IN
I
IN
200mA/div
0
200mA/div
0
1ms/div
1ms/div
_______________________________________________________________________________________
5
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
STROBE STARTUP WAVEFORM
WITH MAIN ALREADY ON
MAIN BRIGHTNESS CHANGE
(1.9mA/LED TO 30mA/LED)
MAX1707 toc15
MAX1707 toc16
5V/div
1V/div
V
V
V
5V/div
1V/div
STB
SDA
OUT
V
OUT
0
0
I
IN
200mA/div
0
100mA/div
0
I
OUT
1ms/div
1ms/div
LINE-TRANSIENT RESPONSE
(4V TO 3.3V TO 4V)
LINE-TRANSIENT RESPONSE WITH
MODE TRANSITION (3.3V TO 2.7V TO 3.3V)
MAX1707 toc17
MAX1707 toc18
1V/div
V
V
IN
IN
1V/div
4V
1V/div
4V
1V/div
V
V
OUT
OUT
200mA/div
0
I
I
OUT
OUT
200mA/div
0
100µs/div
100µs/div
RGB RAMP WAVEFORMS
RGB RAMP WAVEFORMS
(BLUE-TO-YELLOW TRANSITION)
(BLUE-TO-YELLOW TRANSITION)
MAX1707 toc19
MAX1707 toc20
HALF-BRIGHTNESS
DEFAULT RAMP TIME
FULL-BRIGHTNESS
1048ms RAMP TIME
20mA/div
10mA/div
I
I
RED
RED
0
0
I
I
GREEN
20mA/div
10mA/div
GREEN
0
0
20mA/div
0
10mA/div
0
I
I
BLUE
BLUE
200ms/div
40ms/div
6
_______________________________________________________________________________________
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
Pin Description
PIN
NAME
FUNCTION
Power-Supply Voltage Input. Connect PIN to IN. Connect a 4.7µF ceramic capacitor from PIN to
PGND. The input voltage range is 2.7V to 5.5V. PIN is high impedance during shutdown.
1
PIN
Analog Supply Voltage Input. Connect IN to PIN. The input voltage range is 2.7V to 5.5V. IN is high
impedance during shutdown.
2
3
4
IN
Ground. Connect GND to system ground and the ground side of the input bypass capacitor as close
to the IC as possible.
GND
Logic-Input Supply Voltage. Connect V
to the logic supply driving SDA, SCK, and STB. Connect a
DD
V
DD
0.1µF ceramic capacitor from V
to GND.
DD
5
6
M4
M3
M2
M1
F4
2
LED Cathode Connections. Current flowing into these pins is based on the internal I C dimming
registers. The charge pump regulates the lowest LED cathode voltage to 0.15V. Grounding any of
these pins forces output overvoltage protection mode causing OUT to pulse on and off at
approximately 5V. To avoid constantly operating in overvoltage protection mode, any unused LED
cathode connection (M_, S_, or F_) must be connected to OUT. This disables the corresponding
current regulator. These pins are high impedance in shutdown.
7
8
9
10
11
12
13
14
15
F3
F2
M1 through M4 are for main display backlights.
S1 through S3 are for subdisplay backlights or one RGB LED indicator.
F1 through F4 are for LED flash.
F1
S3
S2
S1
Any combination of M_, S_, and F_ can be connected together to drive higher current LEDs.
Strobe Logic Input. Drive STB low to turn on the flash LEDs (F1, F2, F3, F4) at the current specified in
the internal strobe register. Drive STB high to turn off the flash LEDs. Connect to V
are turned on/off only by the I C interface.
if the flash LEDs
16
STB
DD
2
2
17
18
SCK
SDA
I C Clock Input. Data is read on the rising edge of SCK.
2
I C Data Input. Data is read on the rising edge of SCK.
Transfer Capacitor 1 Negative Connection. Connect a 1µF ceramic capacitor from C1N to C1P. C1N
is shorted to IN during shutdown.
19
20
21
22
23
C1N
C1P
Transfer Capacitor 1 Positive Connection. Connect a 1µF ceramic capacitor from C1N to C1P. During
shutdown, if V
> V , C1P is shorted to OUT. If V
< V , C1P is shorted to IN.
OUT IN
OUT
IN
Power Ground. Charge-pump switching ground. Connect to GND and EP as close to the IC as
possible.
PGND
OUT
C2P
Output. Connect a 10µF ceramic capacitor from OUT to PGND. The anodes of all the LEDs connect
to OUT. OUT is pulled to ground through an internal 5kΩ resistor in shutdown.
Transfer Capacitor 2 Positive Connection. Connect a 1µF ceramic capacitor from C2N to C2P. During
shutdown, if V
> V , C2P is shorted to OUT. If V
< V , C2P is shorted to IN.
OUT IN
OUT
IN
Transfer Capacitor 2 Negative Connection. Connect a 1µF ceramic capacitor from C2N to C2P. C2N
is shorted to IN during shutdown.
24
—
C2N
EP
Exposed Paddle. Connect to GND and PGND directly under the IC.
_______________________________________________________________________________________
7
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
C1
C2
1µF
1µF
INPUT
2.7V TO 5.5V
C1P C1N C2P C2N
PIN
IN
OUT
OUT
1x/1.5x/2x REGULATING
CHARGE PUMP
C
10µF
OUT
C
4.7µF
IN
ERROR
AMP 1
PGND
GND
OVP
MAX1707
REFERENCE
0.15V
0.6V
1.25V
SELECT
MIN
2
I C AND
SCK
SDA
STB
CONTROL
S1
S2
S3
D1
D2
D3
BRIGHTNESS CONTROL
STB CONTROL
V
DD
2.7V TO 5.5V
C
VDD
0.1µF
+
+
+
–
–
–
ERROR
AMP 2
M1
M2
M3
M4
D4
D5
D6
D7
R
SET
+
+
+
+
–
–
–
–
F1
F2
F3
F4
D8
D9
D10
D11
+
+
+
+
–
–
–
–
Figure 1. Functional Diagram
_______________________________________________________________________________________
8
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
When the MAX1707 is running in 1.5x mode and the
Detailed Description
input voltage is decreased, the lowest LED cathode
The MAX1707 charge pump operates in three modes to
voltage crosses the 100mV switchover threshold again.
maintain high efficiency over a wide supply voltage
At this point, the MAX1707 changes to the 2x charge-
range. The IC automatically selects between these
pump mode. With the input voltage rising and the
three modes as described in the 1x/1.5x/2x Mode
MAX1707 in 2x mode, the IC changes to 1.5x mode
Switchover section.
once V is greater than 2/3 of the output voltage.
IN
Current-sinking LED cathode connections are provided
to drive four main (M_) and three sub (S_) LEDs at a
regulated current up to 30mA each. The sub LED con-
nections can be used for either subdisplay backlighting
or one RGB indicator. The IC also contains four flash
LED connections (F_) that sink up to 100mA each.
These LED connections can be connected together in
any combination to provide increased current up to
610mA total.
An I2C serial port is used for on/off control and setting
the LED currents in 32 linear steps. When using the
RGB indicator, the I2C port provides 32k colors and
programmable ramp-up/down rates. The camera flash
can be turned on/off by the I2C port or a separate digi-
tal logic input with either method programmed to its
own brightness level.
Soft-Start
The MAX1707 includes soft-start circuitry to limit inrush
current at turn-on and mode transitions. When starting
up, the output capacitor is charged directly from the
input with a ramped current source (with no charge-
pump action) until the output voltage is near the input
voltage. After 512µs, if all the LED cathodes are not
above 100mV, the MAX1707 switches to 1.5x mode
with the LED output current ramped from 1/32 to the
programmed current in 1/32 steps. After another 512µs,
if all the LED cathodes are not above 100mV, the
MAX1707 switches to 2x mode, once again ramping
the LED current from 1/32 to the programmed current in
1/32 steps. Any time the output voltage is less than
1.25V, the soft-start routine is reset to the 1x state. Thus,
the startup time is 512µs, 1024µs, or 1536µs, depending
on what mode is required after the completion of startup.
1x/1.5x/2x Mode Switchover
When the input voltage is higher than the required out-
put voltage needed to drive the LEDs, the MAX1707
pulls OUT up to the input voltage (in 1x mode), while
still regulating the LED current with the current regula-
tors. As the input voltage drops, the lowest LED cath-
ode voltage falls below the 100mV switchover
threshold, and the MAX1707 starts switching in 1.5x
mode. When the input voltage is rising, the transition
Output-Current Settings
The output currents for the main, sub, and flash current
regulators are set using the I2C serial interface (see the
I2C Interface section). The current for the four main
LEDs is always equal and set with a single command.
The currents for the three sub LEDs are set indepen-
dently, allowing them to drive an RGB LED. The cur-
rent-level settings for both the main and sub LEDs
range from 0.9mA to 30mA, defaulting to 15mA each
(see Tables 1, 2, and 3).
from 1.5x to 1x is made when V is greater than V
IN
.
OUT
Table 1. Control Data Byte
SDA CONTROL BYTE
DATA
FUNCTION
COMMAND
C2
0
C1
0
C0
D4
D3
D2
D1
D0
On/Off Control
Main Brightness
Sub1 Brightness
Sub2 Brightness
Sub3 Brightness
Flash Brightness
Strobe Brightness
0
1
0
1
0
1
0
Main
Sub3
Sub2
Sub1
Flash
0
0
32 steps, 30mA/LED max
32 steps, 30mA max
32 steps, 30mA max
32 steps, 30mA max
0
1
0
1
1
0
2
1
0
32 steps, 100mA/LED max, I C enable
1
1
32 steps, 100mA/LED max, STB enable
Temp
Derate
Other Functions
1
1
1
X
X
RGB Ramp Rate
Note: C2 is MSB and D0 is LSB. X = Don’t care.
_______________________________________________________________________________________
9
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
Table 2. Data and LED Currents
DATA
D2
0
LED CURRENT (mA)
D4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
D3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
D1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
D0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
MAIN
0.9
SUB1
0.9
SUB2
0.9
SUB3
0.9
FLASH
3.3
STROBE
3.3
0
1.9
1.9
1.9
1.9
6.5
6.5
0
2.8
2.8
2.8
2.8
9.7
9.7
0
3.8
3.8
3.8
3.8
12.9
16.2
19.4
22.6
25.8
28.9
32.1
35.4
38.6
41.6
44.7
47.9
51.0
54.1
57.2
60.3
63.4
66.3
69.6
72.7
75.8
78.8
81.9
84.9
87.9
91.0
94.0
97.0
100.0
12.9
16.2
19.4
22.6
25.8
28.9
32.1
35.4
38.6
41.6
44.7
47.9
51.0
54.1
57.2
60.3
63.4
66.3
69.6
72.7
75.8
78.8
81.9
84.9
87.9
91.0
94.0
97.0
100.0
1
4.7
4.7
4.7
4.7
1
5.6
5.6
5.6
5.6
1
6.6
6.6
6.6
6.6
1
7.5
7.5
7.5
7.5
0
8.4
8.4
8.4
8.4
0
9.4
9.4
9.4
9.4
0
10.3
11.3
12.2
13.1
14.1
15.0
15.9
16.9
17.8
18.8
19.7
20.6
21.6
22.5
23.4
24.4
25.3
26.3
27.2
28.1
29.1
30.0
10.3
11.3
12.2
13.1
14.1
15.0
15.9
16.9
17.8
18.8
19.7
20.6
21.6
22.5
23.4
24.4
25.3
26.3
27.2
28.1
29.1
30.0
10.3
11.3
12.2
13.1
14.1
15.0
15.9
16.9
17.8
18.8
19.7
20.6
21.6
22.5
23.4
24.4
25.3
26.3
27.2
28.1
29.1
30.0
10.3
11.3
12.2
13.1
14.1
15.0
15.9
16.9
17.8
18.8
19.7
20.6
21.6
22.5
23.4
24.4
25.3
26.3
27.2
28.1
29.1
30.0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
Note: Defaults in bold.
10 ______________________________________________________________________________________
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
Table 3. Control Data Byte (Hexadecimal)
CONTROL BYTE (HEXADECIMAL)
FLASH STROBE
LED CURRENT (mA)
MAIN
20
21
22
23
24
25
26
27
28
29
2A
2B
2C
2D
2E
2F
30
31
32
33
34
35
36
37
38
39
3A
3B
3C
3D
3E
3F
SUB1
40
41
42
43
44
45
46
47
48
49
4A
4B
4C
4D
4E
4F
50
51
52
53
54
55
56
57
58
59
5A
5B
5C
5D
5E
5F
SUB2
60
61
62
63
64
65
66
67
68
69
6A
6B
6C
6D
6E
6F
70
71
72
73
74
75
76
77
78
79
7A
7B
7C
7D
7E
7F
SUB3
80
81
82
83
84
85
86
87
88
89
8A
8B
8C
8D
8E
8F
90
91
92
93
94
95
96
97
98
99
9A
9B
9C
9D
9E
9F
MAIN
0.9
SUB1
0.9
SUB2
0.9
SUB3
0.9
FLASH STROBE
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
AA
AB
AC
AD
AE
AF
B0
B1
B2
B3
B4
B5
B6
B7
B8
B9
BA
BB
BC
BD
BE
BF
C0
C1
C2
C3
C4
C5
C6
C7
C8
C9
CA
CB
CC
CD
CE
CF
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
DA
DB
DC
DD
DE
DF
3.3
6.5
3.3
6.5
1.9
1.9
1.9
1.9
2.8
2.8
2.8
2.8
9.7
9.7
3.8
3.8
3.8
3.8
12.9
16.2
19.4
22.6
25.8
28.9
32.1
35.4
38.6
41.6
44.7
47.9
51.0
54.1
57.2
60.3
63.4
66.3
69.6
72.7
75.8
78.8
81.9
84.9
87.9
91.0
94.0
97.0
100.0
12.9
16.2
19.4
22.6
25.8
28.9
32.1
35.4
38.6
41.6
44.7
47.9
51.0
54.1
57.2
60.3
63.4
66.3
69.6
72.7
75.8
78.8
81.9
84.9
87.9
91.0
94.0
97.0
100.0
4.7
4.7
4.7
4.7
5.6
5.6
5.6
5.6
6.6
6.6
6.6
6.6
7.5
7.5
7.5
7.5
8.4
8.4
8.4
8.4
9.4
9.4
9.4
9.4
10.3
11.3
12.2
13.1
14.1
15.0
15.9
16.9
17.8
18.8
19.7
20.6
21.6
22.5
23.4
24.4
25.3
26.3
27.2
28.1
29.1
30.0
10.3
11.3
12.2
13.1
14.1
15.0
15.9
16.9
17.8
18.8
19.7
20.6
21.6
22.5
23.4
24.4
25.3
26.3
27.2
28.1
29.1
30.0
10.3
11.3
12.2
13.1
14.1
15.0
15.9
16.9
17.8
18.8
19.7
20.6
21.6
22.5
23.4
24.4
25.3
26.3
27.2
28.1
29.1
30.0
10.3
11.3
12.2
13.1
14.1
15.0
15.9
16.9
17.8
18.8
19.7
20.6
21.6
22.5
23.4
24.4
25.3
26.3
27.2
28.1
29.1
30.0
Note: Defaults in bold.
______________________________________________________________________________________ 11
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
mon anode RGB LED. Thirty-two programmable bright-
Table 4. RGB Ramp Rate
ness levels (5 bits) per LED provide a total of 32k col-
CONTROL BYTE RGB RAMP RAMP TIME FROM OFF TO
(HEXADECIMAL) RATE (A/s) FULL BRIGHTNESS (ms)
ors. To smooth the transition between different
color/brightness settings, a controlled ramp is used
when the sub LED current level is changed, when the
sub LEDs are enabled, and when the LEDs are dis-
abled. The ramp rate is set to one of four settings with
the I2C interface (see Table 4).
E0
58.6
0.512
262
E1
0.114
E2
E3
0.0572
0.0286
524
1048
Temperature-Derating Function
The MAX1707 contains a temperature-derating function
that automatically limits the LED current at high tempera-
tures in accordance with the recommended derating
curve of popular white LEDs. The derating function
enables the safe usage of higher LED current at room
temperature, thus reducing the number of LEDs required
to backlight the display. In camera-light applications, the
derating circuit protects the LEDs and PC board from
overheating. The derating circuit limits the LED current
by reducing the LED current above +40°C by approxi-
mately 1.7%/°C. The typical derating function character-
istic is shown in the Typical Operating Characteristics.
The temperature derating function is enabled/disabled
using the I2C interface and is off by default.
*Default in bold.
The flash LEDs are controlled either using the I2C inter-
face or by pulsing the STB input low. There are two reg-
isters in the MAX1707 to set the flash current level. The
FLASH register sets the LED current when the I2C inter-
face is used to pulse the flash LEDs, and the STROBE
register sets the LED current when the STB input is
pulsed. The current-level settings for the flash LEDs
range from 3.3mA to 100mA, with a default of 25.8mA
(see Tables 1, 2, and 3). The strobe register has priority
over the flash register when both strobe and flash are on.
The LED cathode connections (M_, S_, and F_) can be
connected together in any combination to allow the use
of higher current LEDs. For example, to drive a single
flash LED at up to 400mA, connect F1, F2, F3, and F4
together to the cathode of the flash LED.
I2C Interface
An I2C 2-wire serial interface is provided on the
MAX1707 to control LED brightness, flash, temperature
deration, and RGB ramp rate. The serial interface con-
sists of a serial data line (SDA) and a serial clock line
(SCK). Standard I2C write-byte commands are used.
Figure 2 shows a timing diagram for the I2C protocol.
The MAX1707 is a slave-only device, relying upon a
master to generate a clock signal. The master (typically
a microprocessor) initiates data transfer on the bus and
To avoid constantly operating in overvoltage protection
mode, any unused LED cathode connection (M_, S_, or
F_) must be connected to OUT. This disables the corre-
sponding current regulator.
RGB Color and Ramp-Rate Settings
The three sub LED currents are controlled indepen-
dently by the I2C interface, allowing for use of a com-
A
B
C
D
E
F
G
H
I
J
K
L
M
t
t
HIGH
LOW
SCK
SDA
t
t
SU:STO
t
t
BUF
SU:STA
t
HD:STA
t
SU:DAT
HD:DAT
A = START CONDITION
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE (OP/SUS BIT)
H = LSB OF DATA CLOCKED INTO SLAVE
J = ACKNOWLEDGE CLOCKED INTO MASTER
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION, DATA EXECUTED BY SLAVE
M = NEW START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
I = SLAVE PULLS SMBDATA LINE LOW
E = SLAVE PULLS SMBDATA LINE LOW
2
Figure 2. I C Timing Diagram
12 ______________________________________________________________________________________
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
generates SCK to permit data transfer. A master device
communicates to the MAX1707 by transmitting the
Applications Information
Input Ripple
In 1x mode, the input ripple of the MAX1707 is negligi-
ble. When the charge pump is switching in 1.5x or 2x
mode, the input ripple depends on the load current and
the output impedance of the source supply. The worst-
case ripple occurs when the charge pump is operating
in 1.5x mode. The switching waveforms in the Typical
Operating Characteristics show the typical input ripple.
For noise-sensitive applications, input ripple can be
reduced by increasing the input capacitance.
proper 8-bit address (0x9A) followed by the 8-bit con-
trol byte. Each 8-bit control byte consists of a 3-bit
command code and 5 bits of data (see Table 1). Each
transmit sequence is framed by a START (A) condition
and a STOP (L) condition (see Figure 2). Each word
transmitted over the bus is 8 bits long and is always fol-
lowed by an acknowledge clock pulse.
Shutdown Mode
When all the LEDs are off, the MAX1707 turns off the
charge pump and enters low-power shutdown mode.
When in shutdown, OUT is pulled to GND by an internal
5kΩ resistor, discharging the output capacitor. IN and
PIN are high impedance during shutdown, but the I2C
Capacitor Selection
Ceramic capacitors are recommended due to their small
size, low cost, and low ESR. Select ceramic capacitors
that maintain their capacitance over temperature and DC
bias. Capacitors with X5R or X7R temperature character-
istics generally perform well. Recommended values are
shown in the Typical Operating Circuit. Using a larger-
value input capacitor helps to reduce input ripple (see
the Input Ripple section).
interface (powered from V ) remains active. To enter
DD
shutdown, send control byte 0x00 to the I2C interface,
and drive STB high. To exit shutdown, enable any of
the LEDs with the I2C interface or STB input.
STB Logic Input
The STB input is used to control the flash LEDs without
accessing the I2C interface. When STB is driven low,
the flash LEDs are driven to the current set in the
STROBE register. Driving STB low overrides the flash
register settings. With STB high, the flash LEDs are
controlled by the I2C interface flash register and on/off
control.
PC Board Layout and Routing
The MAX1707 is a high-frequency switched-capacitor
regulator. For best circuit performance, use a solid
ground plane and place the capacitors as close to the
IC as possible. Connect the exposed pad to GND and
PGND, and allow sufficient copper area for cooling the
IC. Refer to the MAX1707 evaluation kit for an example
PC board layout.
Output Overvoltage Protection
In case an LED fails or the cathode is shorted to GND,
the output overvoltage protection limits the output to
5V. When the MAX1707 detects the output voltage ris-
ing above 5V, it shuts off the charge pump. The charge
pump restarts once the output voltage has dropped to
4.9V.
Pin Configuration
TOP VIEW
18
17
16
15
14
13
12
11
10
9
C1N 19
C1P 20
PGND 21
OUT 22
C2P 23
F1
F2
F3
To avoid constantly operating in overvoltage protection,
any unused LED cathode connection (M_, S_, or F_)
must be connected to OUT; this disables the corre-
sponding current regulator.
MAX1707ETG
F4
Thermal Shutdown
Thermal shutdown limits total power dissipation in the
MAX1707. When the junction temperature exceeds
+160°C, the MAX1707 turns off, allowing the IC to cool.
The MAX1707 turns on and begins soft-start after the junc-
tion temperature cools by 20°C. This results in a pulsed
output during continuous thermal-overload conditions.
8
M1
M2
24
7
C2N
1
2
3
4
5
6
THIN QFN
4mm x 4mm
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________ 13
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
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.)
PACKAGE OUTLINE,
12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
1
E
21-0139
2
14 ______________________________________________________________________________________
Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs
Package Information (continued)
(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.)
PACKAGE OUTLINE,
12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
2
E
21-0139
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
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