MAXIM MAX1707 Technical data

General Description

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 adap­tive 1x/1.5x/2x charge-pump modes and very-low­dropout 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.

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 ramp­up/down rates. The camera flash may be turned on/off
by the I2C port or a separate digital logic input.

Applications

Cell Phones and Smartphones

PDAs, Digital Cameras, Camcorders

Displays with Up to 11 LEDs

Features

♦ 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

LED/PBATT

)

♦ Adaptive 1x/1.5x/2x Mode Switchover

♦ 0.3% (typ) LED Current Accuracy and Matching

♦ Low Input Ripple and EMI

♦ Low 0.1µA Shutdown Current

♦ Output Overvoltage Protection

♦ Thermal Derating Function Protects LEDs

♦ 24-Pin 4mm x 4mm Thin QFN Package

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x

Charge Pump for Backlight/Flash/RGB LEDs

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

MAX1707

1µF1µF

10µF

0.1µF

IN
PIN

SDA

SCK

STB

GND

OUT

C1P C1N

PGND

C2P

FLASH

MAIN

C2N

4.7µF

I

2

C PORT

ON/OFF AND

BRIGHTNESS

INPUT

2.7V TO 5.5V

OUTPUT
UP TO 610mA

M1
M2

M3
M4

S1
S2
S3
F1
F2
F3
F4

STROBE

ON/OFF

V

LOGIC

V

DD

SUB OR RGB

Typical Operating Circuit

19-3744; Rev 0; 7/05

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.

Pin Configuration appears at end of data sheet.

EVALUATION KIT

AVAILABLE

PART

PIN­PACKAGE

PKG

CODE

MAX1707ETG

24 Thin QFN
4mm x 4mm

T2444-4

†

Purchase of I2C components from Maxim Integrated Products,
Inc., or one of its sublicensed Associated Companies, conveys
a license under the Philips I

2

C Patent Rights to use these com-

ponents in an I

2

C system, provided that the system conforms to

the I

2

C Standard Specification as defined by Philips.

查询MAX1707供应商

TEMP RANGE

-40°C to +85°C

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= V

PIN

= VDD= 3.6V, V

GND

= V

PGND

= 0V, temperature derating disabled, TA= -40°C to +85°C, typical values are at TA=

+25°C, unless otherwise noted.) (Note 1)

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.

VDD, IN, PIN, SCK, SDA, STB, OUT to GND .........-0.3V to +6.0V

M_, S_, F_ to GND ....................................-0.3V to (V

OUT

+ 0.3V)

C1N, C2N to GND .......................................-0.3V to (V

IN

+ 0.3V)

C1P, C2P to GND ..-0.3V to greater of (V

OUT

+ 0.3V) or (VIN+ 0.3V)

PGND to GND .......................................................-0.3V to +0.3V

OUT Short Circuit to GND ..........................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

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

PARAMETER CONDITIONS

UNIT

IN Operating Voltage 2.7 5.5 V

VDD Operating Range 2.7 5.5 V

Undervoltage-Lockout Threshold VIN rising or falling

V

Undervoltage-Lockout Hysteresis 50 mV

Output Overvoltage-Protection Threshold

V

OUT

rising

V

1.5x or 2x mode 4.0 6.5

IN + PIN No-Load Supply Current

10% setting, 1x mode, flash off

mA

TA = +25°C 0.7 5

IN + PIN Shutdown Supply Current

All LEDs off, STB = SDA =
SCK = V

DD

, I2C ready

T

A

= +85°C 0.8

µA

TA = +25°C 0.1 1

VDD Quiescent Current

All LEDs off, STB = SDA =
SCK = V

DD

, I2C ready

T

A

= +85°C 0.1

µA

Startup into 1x mode 0.5

Startup into 1.5x mode 1.0

Soft-Start Time

Startup into 2x mode 1.5

ms

LED Current Derating Function Start
Temperature

Temperature derating enabled

°C

LED Current Derating Function Slope

T

A

= +40°C to +85°C, temperature derating

enabled

%/°C

Default current setting, TA = +25°C -2

+2

LED Current SUB Output Accuracy
(Note 2)

D efaul t cur r ent setti ng , T

A

= - 40°C to + 85°C -5 +5

%

LED Current FLASH and MAIN Output
Accuracy

Default current setting (Note 2) -5

+5 %

M_, S_

Maximum M_, S_, F_ Sink Current

F_ 95

mA

M_, S_ 40 90

LED Dropout Voltage

F_ 40 90

mV

1.5x and 2x Mode Regulation Voltage

mV

1x to 1.5x and 1.5x to 2x Mode Transition
Threshold

V

M_

, VS_, V

F_

falling

mV

MIN TYP MAX

2.25 2.60

4.75 5.00 5.25

100% LED setting (Note 3)

28.5 30.0

0.35

+40

-1.7

±0.3

±0.3

100

150

100

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x

Charge Pump for Backlight/Flash/RGB LEDs

_______________________________________________________________________________________ 3

Note 1: All devices are 100% production tested at TA= +25°C. Limits over the operating temperature range are guaranteed

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.

ELECTRICAL CHARACTERISTICS (continued)

(VIN= V

PIN

= VDD= 3.6V, V

GND

= V

PGND

= 0V, temperature derating disabled, TA= -40°C to +85°C, typical values are at TA=

+25°C, unless otherwise noted.) (Note 1)

PARAMETER CONDITIONS

UNIT

Input Voltage Mode Transition Hysteresis

mV

TA = +25°C

1

M_, S_, F_ Leakage in Shutdown

All LEDs off, STB =
V

DD T

A

= +85°C 0.1

µA

OUT Pulldown Resistance in Shutdown All LEDs off, STB = V

DD

5kΩ

Maximum OUT Current VIN ≥ 3.2V, V

OUT

= 3.9V

mA

1x mode (VIN - V

OUT

) / I

OUT

0.5 2.5

1.5x mode (1.5 x VIN - V

OUT

) / I

OUT

1.5 3.5Open-Loop OUT Resistance

2x mode (2 x V

IN

- V

OUT

) / I

OUT

2.0 4.1

Ω

Switching Frequency 1

MHz

SDA = 111xxx00 2

9

SDA = 111xxx01 2

18

SDA = 111xxx10 2

19

S1, S2, S3 (RGB) Full-Scale Ramp Time

SDA = 111xxx11 2

20

µs

Logic-Input High Voltage VDD = 2.7V to 5.5V

V

Logic-Input Low Voltage VDD = 2.7V to 5.5V 0.4 V

TA = +25°C

1

Logic-Input Current

V

IL

= 0V or VIH =

5.5V

T

A

= +85°C 0.1

µA

SDA Output Low Voltage I

SDA

= 3mA

0.4 V

I2C Clock Frequency 400 kHz

Bus- Fr ee Ti m e Betw een S TART and S TOP

t

BUF

1.3 µs

Hold Time Repeated START Condition t

HD_STA

0.6 0.1 µs

SCK Low Period t

LOW

1.3 0.2 µs

SCK High Period t

HIGH

0.6 0.2 µs

Setup Time Repeated START Condition t

SU_STA

0.6 0.1 µs

SDA Hold Time t

HD_DAT

0

µs

SDA Setup Time t

SU_DAT

50 ns

Setup Time for STOP Condition t

SU_STO

0.6 0.1 µs

Thermal Shutdown

°C

Thermal-Shutdown Hysteresis 20 °C

MIN TYP MAX

150

0.01

610

VDD / 2

0.01

0.03

100

-0.01

+160

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs

4 _______________________________________________________________________________________

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

MAX1707 toc01

EFFICIENCY vs. SUPPLY VOLTAGE

DRIVING 4 MAIN LEDs

SUPPLY VOLTAGE (V)

EFFICIENCY (%)

4.33.93.53.1

20

10

0

30

40

50

60

70

80

90

100

2.7 5.55.14.7

SUPPLY VOLTAGE FALLING

30mA/LED

15mA/LED

1.9mA/LED

0

200

100

500

400

300

800

700

600

900

2.7 3.9 4.33.1 3.5 4.7 5.1 5.5

INPUT CURRENT vs. SUPPLY VOLTAGE
DRIVING LUMILEDS LXCL-PWF1 FLASH

MAX1707 toc02

SUPPLY VOLTAGE (V)

INPUT CURRENT (mA)

400mA

100mA

200mA

0

100

50

250

200

150

400

350

300

450

2.7 3.9 4.33.1 3.5 4.7 5.1 5.5

INPUT CURRENT vs. SUPPLY VOLTAGE

DRIVING 4 MAIN LEDs AND RGB LEDs

MAX1707 toc03

SUPPLY VOLTAGE (V)

INPUT CURRENT (mA)

SUPPLY VOLTAGE FALLING

30mA/LED

15mA/LED

1.9mA/LED

0

100

50

250

200

150

400

350

300

450

2.7 3.9 4.33.1 3.5 4.7 5.1 5.5

INPUT CURRENT vs. SUPPLY VOLTAGE

DRIVING 4 MAIN LEDs

MAX1707 toc04

SUPPLY VOLTAGE (V)

INPUT CURRENT (mA)

1.9mA/LED

SUPPLY VOLTAGE FALLING

30mA/LED

15mA/LED

0

100

50

250

200

150

400

350

300

450

2.7 3.9 4.33.1 3.5 4.7 5.1 5.5

INPUT CURRENT vs. SUPPLY VOLTAGE

DRIVING RGB LEDs

MAX1707 toc05

SUPPLY VOLTAGE (V)

INPUT CURRENT (mA)

SUPPLY VOLTAGE FALLING

30mA/LED

15mA/LED

1.9mA/LED

LED CURRENT MATCHING

vs. SUPPLY VOLTAGE

(MAIN AND RGB AT FULL CURRENT)

MAX1707 toc06

28.8

29.4

29.1

30.6

30.9

30.3

30.0

29.7

31.2

LED CURRENT (mA)

2.7 3.9 4.33.1 3.5 4.7 5.1 5.5
SUPPLY VOLTAGE (V)

4 WHITE
V

F

= 3.4V

RED
V

F

= 1.9V

GREEN
V

F

= 2V

BLUE
V

F

= 4.2V

LED CURRENT MATCHING

vs. SUPPLY VOLTAGE

(MAIN AND RGB AT 1.9mA/LED)

MAX1707 toc07

1.80

1.84

1.82

1.92

1.94

1.90

1.88

1.86

1.96

LED CURRENT (mA)

2.7 3.9 4.33.1 3.5 4.7 5.1 5.5
SUPPLY VOLTAGE (V)

4 WHITE
V

F

= 2.9V

RED
V

F

= 1.7V

GREEN
V

F

= 1.9V

BLUE
V

F

= 3.4V

0

10

5

20

15

25

30

-40 85

LED CURRENT vs. TEMPERATURE

MAX1707 toc08

TEMPERATURE (°C)

LED CURRENT (mA)

10-15 35 60

THERMAL DERATING OFF

THERMAL DERATING ON

4 MAIN OR 4 FLASH LEDs

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x

Charge Pump for Backlight/Flash/RGB LEDs

_______________________________________________________________________________________ 5

50mV/div
(AC-COUPLED)

100mA/div

0

I

IN

50mV/div
(AC-COUPLED)

V

OUT

V

IN

1µs/div

OPERATING WAVEFORMS 1X MODE

MAX1707 toc09

50mV/div
(AC-COUPLED)

100mA/div

0

I

IN

50mV/div
(AC-COUPLED)

V

OUT

V

IN

1µs/div

OPERATING WAVEFORMS 1.5X MODE

MAX1707 toc10

50mV/div
(AC-COUPLED)
100mA/div

0

I

IN

50mV/div
(AC-COUPLED)

V

OUT

V

IN

1µs/div

OPERATING WAVEFORMS 2X MODE

MAX1707 toc11

200mA/div
0

0

I

IN

5V/div

1V/div

V

OUT

V

SDA

1ms/div

MAIN BACKLIGHT STARTUP WAVEFORM

MAX1707 toc12

200mA/div
0

0

I

IN

5V/div
1V/div

V

OUT

V

SDA

1ms/div

MAIN STARTUP WITH RGB ALREADY ON

MAX1707 toc13

200mA/div
0

0

I

IN

5V/div

1V/div

V

OUT

V

SDA

1ms/div

FLASH STARTUP WAVEFORM

MAX1707 toc14

Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs

6 _______________________________________________________________________________________

200mA/div
0

0

I

IN

5V/div

1V/div

V

OUT

V

STB

1ms/div

STROBE STARTUP WAVEFORM

WITH MAIN ALREADY ON

MAX1707 toc15

100mA/div
0

0

I

OUT

5V/div

1V/div

V

OUT

V

SDA

1ms/div

MAIN BRIGHTNESS CHANGE

(1.9mA/LED TO 30mA/LED)

MAX1707 toc16

200mA/div

0

I

OUT

1V/div

4V
1V/div

V

OUT

V

IN

100µs/div

LINE-TRANSIENT RESPONSE

(4V TO 3.3V TO 4V)

MAX1707 toc17

200mA/div
0

I

OUT

1V/div

4V
1V/div

V

OUT

V

IN

100µs/div

LINE-TRANSIENT RESPONSE WITH

MODE TRANSITION (3.3V TO 2.7V TO 3.3V)

MAX1707 toc18

20mA/div

0

0

I

BLUE

20mA/div

0

20mA/div

I

GREEN

I

RED

200ms/div

RGB RAMP WAVEFORMS

(BLUE-TO-YELLOW TRANSITION)

MAX1707 toc19

FULL-BRIGHTNESS
1048ms RAMP TIME

10mA/div

0

0

I

BLUE

10mA/div

0

10mA/div

I

GREEN

I

RED

40ms/div

RGB RAMP WAVEFORMS

(BLUE-TO-YELLOW TRANSITION)

MAX1707 toc20

HALF-BRIGHTNESS
DEFAULT RAMP TIME

Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x

Charge Pump for Backlight/Flash/RGB LEDs

_______________________________________________________________________________________ 7

Pin Description

PIN NAME FUNCTION

1PIN

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.

2IN

Analog Supply Voltage Input. Connect IN to PIN. The input voltage range is 2.7V to 5.5V. IN is high
impedance during shutdown.

3 GND

Ground. Connect GND to system ground and the ground side of the input bypass capacitor as close
to the IC as possible.

4V

DD

Logic-Input Supply Voltage. Connect VDD to the logic supply driving SDA, SCK, and STB. Connect a

0.1µF ceramic capacitor from V

DD

to GND.

5M4

6M3

7M2

8M1

9F4

10 F3

11 F2

12 F1

13 S3

14 S2

15 S1

LED Cathode Connections. Current flowing into these pins is based on the internal I

2

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.

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.

Any combination of M_, S_, and F_ can be connected together to drive higher current LEDs.

16 STB

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

DD

if the flash LEDs
are turned on/off only by the I

2

C interface.

17 SCK I2C Clock Input. Data is read on the rising edge of SCK.

18 SDA I2C Data Input. Data is read on the rising edge of SCK.

19 C1N

Transfer Capacitor 1 Negative Connection. Connect a 1µF ceramic capacitor from C1N to C1P. C1N
is shorted to IN during shutdown.

20 C1P

Transfer Capacitor 1 Positive Connection. Connect a 1µF ceramic capacitor from C1N to C1P. During
shutdown, if V

OUT

> V

IN

, C1P is shorted to OUT. If V

OUT

< V

IN

, C1P is shorted to IN.

21 PGND

Power Ground. Charge-pump switching ground. Connect to GND and EP as close to the IC as
possible.

22 OUT

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.

23 C2P

Transfer Capacitor 2 Positive Connection. Connect a 1µF ceramic capacitor from C2N to C2P. During
shutdown, if V

OUT

> VIN, C2P is shorted to OUT. If V

OUT

< VIN, C2P is shorted to IN.

24 C2N

Transfer Capacitor 2 Negative Connection. Connect a 1µF ceramic capacitor from C2N to C2P. C2N
is shorted to IN during shutdown.

—EPExposed Paddle. Connect to GND and PGND directly under the IC.

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs

8 _______________________________________________________________________________________

BRIGHTNESS CONTROL

STB CONTROL

SELECT

MIN

ERROR
AMP 1

I2C AND

CONTROL

MAX1707

SCK

S1

D1

S2

D2

S3

D3

+

–

+

–

+

–

INPUT

2.7V TO 5.5V

2.7V TO 5.5V

1.25V

OUT

OUT

OVP

C

IN

4.7µF

C

VDD

0.1µF

C

OUT

10µF

ERROR
AMP 2

R

SET

M1

D4

M2

D5

M3

D6

M4

D7

+

–

+

–

+

–

+

–

SDA

STB

V

DD

C1

1µF

C1P

PIN

PGND

IN

C1N C2P C2N

C2

1µF

1x/1.5x/2x REGULATING

CHARGE PUMP

GND

REFERENCE

0.15V

0.6V

F1

D8

F2

D9

F3

D10

F4

D11

+

–

+

–

+

–

+

–

Figure 1. Functional Diagram

Detailed Description

The MAX1707 charge pump operates in three modes to
maintain high efficiency over a wide supply voltage
range. The IC automatically selects between these
three modes as described in the 1x/1.5x/2x Mode
Switchover section.

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 con­nections 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 digi­tal logic input with either method programmed to its
own brightness level.

1x/1.5x/2x Mode Switchover

When the input voltage is higher than the required out­put 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 regula­tors. As the input voltage drops, the lowest LED cath­ode voltage falls below the 100mV switchover
threshold, and the MAX1707 starts switching in 1.5x
mode. When the input voltage is rising, the transition
from 1.5x to 1x is made when VINis greater than V

OUT

.

When the MAX1707 is running in 1.5x mode and the
input voltage is decreased, the lowest LED cathode
voltage crosses the 100mV switchover threshold again.
At this point, the MAX1707 changes to the 2x charge­pump mode. With the input voltage rising and the
MAX1707 in 2x mode, the IC changes to 1.5x mode
once VINis greater than 2/3 of the output voltage.

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 charge­pump 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.

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 indepen­dently, allowing them to drive an RGB LED. The cur­rent-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).

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x

Charge Pump for Backlight/Flash/RGB LEDs

_______________________________________________________________________________________ 9

Table 1. Control Data Byte

SDA CONTROL BYTE

COMMAND DATA

FUNCTION

C2 C1 C0 D4 D3 D2 D1 D0

On/Off Control 0 0 0 Main Sub3 Sub2 Sub1 Flash

Main Brightness 0 0 1 32 steps, 30mA/LED max

Sub1 Brightness 0 1 0 32 steps, 30mA max

Sub2 Brightness 0 1 1 32 steps, 30mA max

Sub3 Brightness 1 0 0 32 steps, 30mA max

Flash Brightness 1 0 1 32 steps, 100mA/LED max, I2C enable

Strobe Brightness 1 1 0 32 steps, 100mA/LED max, STB enable

Other Functions 1 1 1 X X

Temp

Derate

RGB Ramp Rate

Note: C2 is MSB and D0 is LSB. X = Don’t care.

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs

10 ______________________________________________________________________________________

Table 2. Data and LED Currents

DATA LED CURRENT (mA)

D4 D3 D2 D1 D0 MAIN SUB1 SUB2 SUB3

STROBE

000000.90.9 0.9 0.9 3.3 3.3

000011.91.9 1.9 1.9 6.5 6.5

000102.82.8 2.8 2.8 9.7 9.7

000113.8 3.8 3.8 3.8 12.9 12.9

001004.7 4.7 4.7 4.7 16.2 16.2

001015.6 5.6 5.6 5.6 19.4 19.4

001106.6 6.6 6.6 6.6 22.6 22.6

001117.57.5 7.5 7.5 25.8 25.8

010008.4 8.4 8.4 8.4 28.9 28.9

010019.4 9.4 9.4 9.4 32.1 32.1

0101010.3 10.3 10.3 10.3 35.4 35.4

0101111.3 11.3 11.3 11.3 38.6 38.6

0110012.2 12.2 12.2 12.2 41.6 41.6

0110113.1 13.1 13.1 13.1 44.7 44.7

0111014.1 14.1 14.1 14.1 47.9 47.9

0111115.0 15.0 15.0 15.0 51.0 51.0

1000015.9 15.9 15.9 15.9 54.1 54.1

1000116.9 16.9 16.9 16.9 57.2 57.2

1001017.8 17.8 17.8 17.8 60.3 60.3

1001118.8 18.8 18.8 18.8 63.4 63.4

1010019.7 19.7 19.7 19.7 66.3 66.3

1010120.6 20.6 20.6 20.6 69.6 69.6

1011021.6 21.6 21.6 21.6 72.7 72.7

1011122.5 22.5 22.5 22.5 75.8 75.8

1100023.4 23.4 23.4 23.4 78.8 78.8

1100124.4 24.4 24.4 24.4 81.9 81.9

1101025.3 25.3 25.3 25.3 84.9 84.9

1101126.3 26.3 26.3 26.3 87.9 87.9

1110027.2 27.2 27.2 27.2 91.0 91.0

1110128.1 28.1 28.1 28.1 94.0 94.0

1111029.1 29.1 29.1 29.1 97.0 97.0

1111130.0 30.0 30.0 30.0 100.0 100.0

Note: Defaults in bold.

FLASH

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x

Charge Pump for Backlight/Flash/RGB LEDs

______________________________________________________________________________________ 11

Table 3. Control Data Byte (Hexadecimal)

CONTROL BYTE (HEXADECIMAL) LED CURRENT (mA)

MAIN

STROBE

20 40 60 80 A0 C0 0.9 0.9 0.9 0.9 3.3 3.3

21 41 61 81 A1 C1 1.9 1.9 1.9 1.9 6.5 6.5

22 42 62 82 A2 C2 2.8 2.8 2.8 2.8 9.7 9.7

23 43 63 83 A3 C3 3.8 3.8 3.8 3.8 12.9 12.9

24 44 64 84 A4 C4 4.7 4.7 4.7 4.7 16.2 16.2

25 45 65 85 A5 C5 5.6 5.6 5.6 5.6 19.4 19.4

26 46 66 86 A6 C6 6.6 6.6 6.6 6.6 22.6 22.6

27 47 67 87 A7 C7 7.5 7.5 7.5 7.5 25.8 25.8

28 48 68 88 A8 C8 8.4 8.4 8.4 8.4 28.9 28.9

29 49 69 89 A9 C9 9.4 9.4 9.4 9.4 32.1 32.1

2A 4A 6A 8A AA CA 10.3 10.3 10.3 10.3 35.4 35.4

2B 4B 6B 8B AB CB 11.3 11.3 11.3 11.3 38.6 38.6

2C 4C 6C 8C AC CC 12.2 12.2 12.2 12.2 41.6 41.6

2D 4D 6D 8D AD CD 13.1 13.1 13.1 13.1 44.7 44.7

2E 4E 6E 8E AE CE 14.1 14.1 14.1 14.1 47.9 47.9

2F 4F 6F 8F AF CF 15.0 15.0 15.0 15.0 51.0 51.0

30 50 70 90 B0 D0 15.9 15.9 15.9 15.9 54.1 54.1

31 51 71 91 B1 D1 16.9 16.9 16.9 16.9 57.2 57.2

32 52 72 92 B2 D2 17.8 17.8 17.8 17.8 60.3 60.3

33 53 73 93 B3 D3 18.8 18.8 18.8 18.8 63.4 63.4

34 54 74 94 B4 D4 19.7 19.7 19.7 19.7 66.3 66.3

35 55 75 95 B5 D5 20.6 20.6 20.6 20.6 69.6 69.6

36 56 76 96 B6 D6 21.6 21.6 21.6 21.6 72.7 72.7

37 57 77 97 B7 D7 22.5 22.5 22.5 22.5 75.8 75.8

38 58 78 98 B8 D8 23.4 23.4 23.4 23.4 78.8 78.8

39 59 79 99 B9 D9 24.4 24.4 24.4 24.4 81.9 81.9

3A 5A 7A 9A BA DA 25.3 25.3 25.3 25.3 84.9 84.9

3B 5B 7B 9B BB DB 26.3 26.3 26.3 26.3 87.9 87.9

3C 5C 7C 9C BC DC 27.2 27.2 27.2 27.2 91.0 91.0

3D 5D 7D 9D BD DD 28.1 28.1 28.1 28.1 94.0 94.0

3E 5E 7E 9E BE DE 29.1 29.1 29.1 29.1 97.0 97.0

3F 5F 7F 9F BF DF 30.0 30.0 30.0 30.0

100.0

Note: Defaults in bold.

SUB1 SUB2 SUB3 FLASH STROBE MAIN SUB1 SUB2 SUB3 FLASH

100.0

MAX1707

The flash LEDs are controlled either using the I2C inter­face or by pulsing the STB input low. There are two reg­isters in the MAX1707 to set the flash current level. The
FLASH register sets the LED current when the I2C inter­face 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.

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.

RGB Color and Ramp-Rate Settings

The three sub LED currents are controlled indepen­dently by the I

2

C interface, allowing for use of a com-

mon anode RGB LED. Thirty-two programmable bright­ness levels (5 bits) per LED provide a total of 32k col­ors. 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 dis­abled. The ramp rate is set to one of four settings with
the I

2

C interface (see Table 4).

Temperature-Derating Function

The MAX1707 contains a temperature-derating function
that automatically limits the LED current at high tempera­tures 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 approxi­mately 1.7%/°C. The typical derating function character­istic is shown in the Typical Operating Characteristics.
The temperature derating function is enabled/disabled
using the I

2

C interface and is off by default.

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 con­sists 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

Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs

12 ______________________________________________________________________________________

Table 4. RGB Ramp Rate

CONTROL BYTE

(HEXADECIMAL)

RGB RAMP

R A M P TI M E FR O M OF F T O

F U L L BR I G H T N ESS ( m s )

E0 58.6 0.512

E1 0.114 262

E2 0.0572 524

E3 0.0286 1048

Figure 2. I2C Timing Diagram

*Default in bold.

RATE (A/s)

AB CDEFG HIJK

SCK

SDA

t

t

SU:STA

HD:STA

A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SMBDATA LINE LOW

t

t

LOW

HIGH

t

SU:DAT

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE (OP/SUS BIT)
H = LSB OF DATA CLOCKED INTO SLAVE
I = SLAVE PULLS SMBDATA LINE LOW

t

HD:DAT

L M

t

t

SU:STO

BUF

J = ACKNOWLEDGE CLOCKED INTO MASTER
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION, DATA EXECUTED BY SLAVE
M = NEW START CONDITION

generates SCK to permit data transfer. A master device
communicates to the MAX1707 by transmitting the
proper 8-bit address (0x9A) followed by the 8-bit con­trol 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 fol­lowed 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
interface (powered from VDD) remains active. To enter
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.

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 ris­ing above 5V, it shuts off the charge pump. The charge
pump restarts once the output voltage has dropped to

4.9V.

To avoid constantly operating in overvoltage protection,
any unused LED cathode connection (M_, S_, or F_)
must be connected to OUT; this disables the corre­sponding current regulator.

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 junc­tion temperature cools by 20°C. This results in a pulsed
output during continuous thermal-overload conditions.

Applications Information

Input Ripple

In 1x mode, the input ripple of the MAX1707 is negligi­ble. 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 worst­case 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.

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 character­istics 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).

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.

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x

Charge Pump for Backlight/Flash/RGB LEDs

______________________________________________________________________________________ 13

23

24

22

21

8

7

9

IN

V

DD

M4

M3

10

PIN

SCK

S1

S2

SDA

S3

12

OUT

456

1718 16 14 13

C2P

C2N

F3

F4

M1

M2

MAX1707ETG

GND

STB

3

15

PGND

20

11

F2

C1P

19

12

F1

C1N

THIN QFN

4mm x 4mm

TOP VIEW

Pin Configuration

Chip Information

PROCESS: BiCMOS

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x
Charge Pump for Backlight/Flash/RGB LEDs

14 ______________________________________________________________________________________

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

.)

24L QFN THIN.EPS

PACKAGE OUTLINE,

21-0139

2

1

E

12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm

MAX1707

Light-Management IC with Efficient 1x/1.5x/2x

Charge Pump for Backlight/Flash/RGB LEDs

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.

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,

21-0139

2

2

E

12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm