MT7655

Color/brightness Switching
Maximizing IC Performance Linear Constant Current LED driver

DESCRIPTION FEATURES
MT7655 is a linear constant current LED driver • Wall switch adjusting LED color
with color temperature and brightness switching temperature and brightness
functions, and the output current is • Color and brightness switching via SEL pin
programmable. • Programmable output current: 1mA~45mA
• High constant current accuracy: ±5%
With integrated high-voltage MOS and high-
• Inherent thermal regulation
voltage JFET, simple peripheral circuit and low
• No EMC issue
BOM cost are achieved.
• No VCC issue
MT7655 features thermal regulation function to • Suitable for DOB scheme
balance the output power and chip temperature. • Simple peripheral circuit with low BOM cost
Once the temperature exceeds the threshold, the • Available in ESOP8 package
chip gradually decreases the output current to
ensure system reliability.
APPLICATIONS
• Bulb
• Fluorescent light
• Downlight
• Ceiling lamp

TYPICAL APPLICATION CIRCUIT

R1 BD

VR

MT7655 R6
LEDs
NC VIN
R2
SEL NC

CS1 GND OUT1 Cool Warm

C1 R3 CS2 OUT2

R4 R5

Low PF, with electrolytic, color temperature switching circuit

R1 BD
VR

MT7655 R6
LEDs
NC VIN
R2
SEL NC

CS1 GND OUT1

C1 R3 R4
CS2 OUT2

R5

Low PF, with electrolytic, brightness switching circuit

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 MT7655
Color/brightness Switching
Maximizing IC Performance Linear Constant Current LED driver

ABSOLUTE MAXIMUM RATINGS

OUT pin voltage -0.5V ~ 500V
OUT pin current 1mA ~ 45mA
Lead temperature (soldering, 10 sec.) 260°C
Maximum power consumption (PDMAX) 1.2W
Storage temperature (TSTG) -55°C ~ 150°C
Operating junction temperature (TJ) -40°C ~ 150°C

THERMAL RESISTANCE①
Junction to ambient (RθJA) 85°C/W
Junction to case (RθJC) 50°C/W

Note:
① RθJA, RθJC are measured in the natural convection at T A = 25°C on a low effective single layer thermal
conductivity test board of JEDEC 51-3 thermal measurement standard. Test condition: Device mounted on 2” X
2” FR-4 substrate PCB, 2oz copper, with minimum recommended pad on top layer and thermal vias to bottom
layer ground plane.

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 MT7655
Color/brightness Switching
Maximizing IC Performance Linear Constant Current LED driver

ORDERING INFORMATION
Moisture
Part Number Package Packing Method Chip Mark
Sensitivity Level
MT7655
Tape
MT7655 ESOP8 3 YYWWXX
4,000pcs/Reel
XXXX

PIN CONFIGURATION

NC 1 8 VIN Chip Mark

YYWWXX
MT7655

SEL 2 7 NC MT7655: Part Number

XXXX

CS1 3 6 OUT1 Y: Year Code

GND
CS2 4 5 OUT2 W: Week Code
X: Manufacture code
(ESOP8)

PIN DESCRIPTION
Name Pin No. Description
SEL 2 Logic control pin, adjusting color temperature and brightness.
CS1 3 Current setting pin, setting OUT1 current.
CS2 4 Current setting pin, setting OUT2 current.
OUT2 5 Constant current output pin 2.
OUT1 6 Constant current output pin 1.
NC 1,7 Floating pin.
VIN 8 High voltage power supply pin of the chip.
Bottom plane Chip ground.

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 MT7655
Color/brightness Switching
Maximizing IC Performance Linear Constant Current LED driver

ELECTRICAL CHARACTERISTICS
Test conditions: TA=25°C, unless otherwise stated.

Symbol Parameter Conditions Min Typ Max Unit

IO Output current 1 45 mA
Breakdown voltage of OUT
VOUT_BV IOUT=0 500 V
pin
IQ Quiescent current VOUT=30V, CS floating 0.14 mA
ISEL SEL pin current 30 μA
VIN=30V,
VCS1=10V, VCS2=10V,
0.57 0.6 0.63 V
only OUT1 or OUT2
outputs
VCS CS pin voltage VIN=30V,
VCS1=10V,
VCS2=10V, 0.285 0.3 0.315 V
OUT1 and OUT2 output
simultaneously
AIOUT IOUT error IOUT=20mA ±5 %
TOTR Thermal regulation threshold 140 °C

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 MT7655
Color/brightness Switching
Maximizing IC Performance Linear Constant Current LED driver

APPLICATION INFORMATION
MT7655 is a linear constant current LED driver with color temperature and brightness switching
functions. The chip integrates high-voltage MOS and high-voltage JFET, which is mainly applicable to
high-voltage linear constant current applications.

Startup

After powered on, VIN pin charges the capacitor of VCC pin through the internal high-voltage JEFT.
When VCC pin voltage exceeds 8V, the chip starts to work.

Color Temperature Switching

MT7655 switches color temperature through the SEL pin. Their relationship is shown in the table below.
SEL Output Switching Order LED Working Mode
Floating OUT2→OUT1→(OUT1+OUT2) Single Color→Single Color→Double Color
Shorted to ground OUT2→(OUT1+OUT2)→OUT1 Single Color→Double Color→Single Color
100KΩ Resistor (OUT1+OUT2)→OUT2→OUT1 Double Color→Single Color→Single Color

If only OUT1 or OUT2 outputs, the internal reference voltage is 0.6V; if OUT1 and OUT2 output
simultaneously, the internal reference voltage is 0.3V.

Brightness Switching Mode

MT7655 switches brightness through the SEL pin. Their relationship is shown in table below.

LED Current
SEL Output Switching Order RCS’s Connection
Switching Order
Connect RCS2 to ground 100%-X%-50%
Floating OUT2→OUT1→(OUT1+OUT2)
Connect RCS1 to ground X%-100%-50%
Connect RCS2 to ground 100%-50%-X%
Shorted to ground OUT2→(OUT1+OUT2)→OUT1
Connect RCS1 to ground X%-50%-100%
Connect RCS2 to ground 50%-100%-X%
100KΩ Resistor (OUT1+OUT2)→OUT2→OUT1
Connect RCS1 to ground 50%-X%-100%

Where, RCS1 is the resistance of CS1; RCS2 is the resistance of CS2.

The relationship between brightness and output current is shown below:

Output Current
Brightness
Connect RCS1 to ground Connect RCS2 to ground
100% 0.6V/RCS1 0.6V/RCS2
50% 0.3V/RCS1 0.3V/RCS2
X% 0.6V/(RCS1+ RCS2) 0.6V/(RCS1+ RCS2)

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 MT7655
Color/brightness Switching
Maximizing IC Performance Linear Constant Current LED driver

System Switch Switching and Reset Time

The MT7655 achieves 0.1S switching, and the reset time of the system is controlled by the capacitor.
After the system is powered on, when the VIN pin voltage is less than 6V, the chip returns to its initial
state. The reset time increases with the increase of electrolytic capacity.

Multiple Chips Connected in Parallel to Improve System Power

For the application that requires large output power, it may cause the chip temperature to be too high,
under such conditions, multiple chips can be connected in parallel to improve system power. Refer to
the figure below.

R1 BD
VR

MT7655 R6
LEDs
NC VIN
R2
SEL NC
C1
CS1
GND OUT1 Cool Warm

R3 R4 CS2 OUT2

R5

MT7655 R11
NC VIN

SEL NC

CS1 GND OUT1

R7 CS2 OUT2

R8 R9

Figure 1 two MT7654 connected in parallel citcuit

PCB Precautions

1. NC pin is suspended to prevent high-voltage creepage;

2. The bonding pad at the bottom of the chip must be grounded and as far away from other pins as
possible.

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 MT7655
Color/brightness Switching
Maximizing IC Performance Linear Constant Current LED driver

PACKAGE OUTLINE AND DIMESION

Important Notice
• Maxic Technology Incorporated (Maxic) reserves the right to make correction, modifications,
enhancements, improvements and other changes to its products and services at any time and to
discontinue any product or service without notice. Customers should obtain the latest relevant
information before placing orders and should verify that such information is current and complete.
All products are sold subject to Maxic’s terms and conditions of sale supplied at the time of order
acknowledgement.
• Reproduction, copying, transferring, reprinting this paper without Maxic’s written permission is
prohibited.
• Maxic assumes no liability for applications assistance or the design of customers’ products. Maxic
warrants the performance of its products to the specifications applicable at the time of sale.
Customers are responsible for their products and applications using Maxic components. To
minimize the risks associated with customers’ products and applications, customers should provide
adequate design and operating safeguards.

Rev. 0.90 www.maxictech.com Page 7