LDS9003-002-T2【PDF 18/30 页】IC TEMP/PWM CONTROLLER 16WQFN

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LDS9003 / 9001

?009 IXYS Corp.

Doc. No. 9003/9001_DS, Rev. N1.0

Characteristics subject to change without notice

50h to 5Fh, 60h to 6Fh, and 70h to 7Fh store the

correction profiles for LUT1, LUT2, and LUT3

respectively.

Figure 11: Global Dimming in Logarithmic Mode

in percent vs. register 04h data

(0% dimming = full LED brightness)

Each register stores a 4 bit adjustment code for two

5篊 temperature steps in its lower (bits 3:0) and

higher (bits 7:4) nibble. User loadable PWM

correction codes in the 1x scale mode represent 0 to

-7 PWM de-rating steps. In the 2 x scale mode the

correction codes represent 0 to -14 PWM steps.

Additionally, the IPWM current sources are disabled

(i.e. 0 DC current = 0% PWM duty cycle) if the

measured LED junction temperature exceeds a

preset value that is loaded in register 4Ah

The LED-Sense

engine periodically measures the

LED junction temperature on three TSENSEx

channels (just TSENSE for LDS9001) and encodes

the value into 5-bit T-codes representing 5

temperature intervals from -35 to +120

The measured T-code value addresses the stored

?PWM correction codes stored in the LUT registers

to adjust the PWM duty cycle. Therefore this reduces

the average current through the LEDs as defined by

the LUT table.

The user loads specific ?PWM correction codes into

the LUT(s) for every 5篊 temperature step from

35篊 to 120篊, as prior discussed, to meet desired

current and power vs LED junction temperature.

LUT correction codes are subtracted from the user-

set duty cycle/dimming code (dynamic mode) loaded

in registers 05h, 06h, and 07h and the global

dimming level code, if used, to maintain reliable LED

current levels.

The LDS9003/9001 includes a 10-bit ADC and digital

processing engine to determine LED temperatures

approximately every 2.5 seconds. The proprietary

LED-Sense

algorithm allows direct measurement of

LED junction temperatures on the TSENSEx sensing

channels, without the need for an external

temperature sensor. Additionally an on-chip silicon

temperature sensing diode is also measured to

enhance temperature estimation accuracy.

C Interface

The LDS9003/9001 uses a 2-wire serial I

C-bus

interface. The SDAT and SCLK lines comply with the

C electrical specification and should be terminated

with pull-up resistors to the logic voltage supply.

When the bus is not used, both lines are high. The

device supports a maximum bus speed of 400kbit/s.

The serial bit sequence is shown at REGISTER

DEFINITION AND PROGRAMMING section for read

and write operations into the registers. Read and

write instructions are initiated by the master

controller/CPU and acknowledged by the slave LED

driver.

The LDS9003/9001 allows user to choose between

two I

C addresses by connecting SADD pin (#3)

either to ground, or V

pin (see Table ).

Table 13: LDS9003/9001 I

C Slave Addresses

C Address

SADD pin

connected to

Binary code

Hex

Ground

001 0001

11h

101 0101

55h

For further details on the I

C protocol, please refer to

the I

C-Bus Specification, document number 9398-

393-40011, from Philips Semiconductors.

Over-Temperature Protection

If the die temperature exceeds +150癈, the driver will

enter shutdown mode. The LDS9003/9001 requires

restart after die temperature falls below 130癈.

OPTIONAL USE of EXTERNAL TEMPERATURE

DIODE

The LDS9003/9001 also provides the option for using

an external remote temperature-sensing diode device

such as a 2N3904. To use this option the diode

anode should be connected to the corresponding

TSENSEx channel. The cathode should be

connected to GND.

STANDBY MODE

The LDS9003/9001 has a soft standby or sleep

mode, which the customer may set by I

C interface

by addressing register 1Fh with bit 6 = 1 (see Table

4).

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