MX881R [IXYS]

LED Driver, PDSO16, 3 X 5 MM, DFN-16;


型号：	MX881R
厂家：	IXYS CORPORATION
描述：	LED Driver, PDSO16, 3 X 5 MM, DFN-16 驱动光电二极管接口集成电路
文件：	总13页 (文件大小：296K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MX881

IXYS

Xenon Flash Controller & LED Torch Driver

Features:

General Description

The MX881 offers a highly integrated Xenon Flash

controller, providing an ideal solution for small form

• Highly Integrated Solution that includes:

Optimized Flyback Boost Converter

Controller, IGBT Driver, 100mA LED Torch

Driver, and Transformer Drive Transistor

• Small Size (3mm x 5mm DFN-16)

• High Efficiency

• 3.0 to 5.5 Volt Battery Operation

• 1.65 to 5.5 Volt Digital Interface Operation

• Low Shut Down Current: 0.1µA

• SPI and I²C Bus Compatibility

factor flash and torch lighting applications. The

MX881 integrates a user programmable Controller,

IGBT Driver, 100mA LED Torch Driver, and

Transformer Drive Transistor to significantly reduce

component count, solution size, and design

complexity.

The Boost Control Logic manages the peak primary

current and off time to optimize charge time and

control average battery current.

• Programmable Average Battery Current:

(50mA – 220mA)

The Charge Cycle Control starts the charge cycle on

a low to high transition of the CHARGE input. Then

detects when the output voltage has reached the

desired voltage and stops the Boost Control Logic,

while asserting the DONE output signal.

The SPI/I²C serial interface adds the flexibility of 6

programmable average battery currents and 4

programmable high voltage output levels for the

flash function.

• Programmable Output Voltage: (300V - 330V)

Applications:

• Camera Cell Phones, Digital Still Cameras, and

Optical Film Cameras

Ordering Information

Qty

Part No.

MX881R

Description

3mm X 5mm DFN-16

MX881RTR DFN-16 Tape & Reel

2000

Typical Application

VHV

500V Total

Switching

Diodes

1:10 min.

MX881

CONTROLLER / DRIVER

22 uF

SEC

VCC

TRIGGER

CAPACITOR

FLASH

TUBE

Boost Control

Logic

PEAK

DVCC

VFB

CHARGE

Charge

Cycle Logic

DONE

VOUT

BATT

IGBTGATE

IXYS

IGBT

FLASH

IGBT

DRIVER

SPI / I2C

Interface to

set VOUT

& IAVE

SPI / I2C

X 4

ISET

LED

LED_EN

Bandgap

REF

GND

MX881

Drawing No. 088109

7/30/07

www.claremicronix.com

MX881

IXYS

Boost Switch: When turned on, current flows in the primary of the flyback transformer. The energy

stored in the transformer is transferred to the secondary as high voltage when the boost switch is turned

off.

IGBT Driver: Switches the VCC supply to the IGBT gate when the FLASH signal is brought high. If

FLASH is low, the IGBT gate is driven to ground.

LED Driver: When LED_EN is high, the LED pin will sink 100mA to GND. If LED_EN is low, the LED

pin is high impedance.

Pin Description

Pin No.

Pin Name Description

VCC

Supply voltage from battery, (3.0V – 5.5V). Must be connected to VDVCC.

DVCC

Digital supply voltage for I/O logic (1.65V-5.5V)

Low level stops the charging cycle and puts the device into power down mode.

Charge remains on the high voltage capacitor. A high level starts a charging cycle.

Charging continues until either the correct voltage is reached or CHARGE is brought

low.

CHARGE

Open drain output that transitions high when the capacitor reaches the desired

voltage. This output is normally high except when charging so that standby current is

minimized. (Pull-up resistor not sourcing current).

Feedback voltage input from voltage divider that determines when the output has

reached the desired voltage.

DONE

VFB

A high level will cause the IGBT to turn on firing the flash. A low level will turn the

IGBT off. FLASH can be brought low to shorten the flash pulse for red-eye reduction.

High level enables the I²C interface, low level enables SPI interface.

FLASH

ISEL

Serial port chip enable. A low on this pin enables the SPI interface to receive data. If

SCEn is asserted low while in the I2C mode, the serial interface and control register

are reset.

SCEn

SCLK

Clock input for SPI and I²C interface.

Data input and output for SPI interface. Data input and acknowledge/data output for

I²C interface. This output is open drain for I²C output data.

SDATA

Connection to internal power transistor that drives the negative terminal of the

transformer primary coil.

Connection to negative terminal of the transformer secondary. This input is grounded

internally through a low impedance used to sense the secondary transformer current.

LSEC

IGBTGATE IGBT Gate driver output.

A high level will cause the 100mA LED current regulator to turn on.

V_F= V_BATT

100mA LED current regulator. Connect the cathode of the torch LED to this pin.

V_F= V_BATT

LED_EN

LED

Exposed

Pad

GND

N/C

Ground Terminal.

No Connect. Do not connect to any signal, ground or power source.

MX881

Drawing No. 088109

7/30/07

www.claremicronix.com

MX881

IXYS

Absolute Maximum Ratings

Symbol

VCC, DVCC

V_IN

V_SW

T_STG

Parameter

Rating

0.3 to 7.0

-0.3 to VCC+0.3

-0.3 to 55

-40 to +150

Unit

DC Supply Voltage

DC Input Voltage

Voltage On SW pad

Storage Temperature

^oC

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 under "recommended operating conditions" is not implied. Exposure to absolute-maximum-

rated conditions for extended periods may affect device reliability.

Recommended Operating Conditions

Symbol

VCC

DVCC

V_IN

V_SW

T_J

Parameter

Rating

3 to 5.5

1.65 to 5.5

0 to DVCC

0 to 40

Unit

Analog and Digital Supply Voltage

Digital I/O Supply Voltage

DC Input Voltage

Voltage On SW pad

Junction Temperature

-20 to +115

^oC

MX881

7/30/07

Drawing No. 088109

www.claremicronix.com

MX881

IXYS

DC Characteristics

Junction temperature range -20 to +115°C

Symbol Parameter

Condition

Min

Typ

3.6

3.3

Max

Unit

Supply Voltage – Analog and

voltage doubler

AVCC

5.5

DVCC

I_CC

Supply Voltage – Digital I/O

Supply Current (When Charging)

1.65

5.5

µA

@ 25° C

I_STANDBYSupply Current (Not Charging)

I_{SW_LEAK}SW pin Leakage Current

0.1

@ 25° C Vsw = 40V

Schmitt trigger, positive-going

threshold (All digital inputs)

1.65V < DVCC < 2.4V

V_T+

1.3

1.6

2.1

Schmitt trigger, negative-going

threshold (All digital inputs)

1.65V < DVCC < 2.4V

2.4V < DVCC < 3.6V

V_T-

0.4

0.15

V_hys

V_T+

Hysteresis, Schmitt trigger

Schmitt trigger, positive-going

threshold (All digital inputs)

Schmitt trigger, negative-going

threshold (All digital inputs)

Hysteresis, Schmitt trigger

Schmitt trigger, positive-going

threshold (All digital inputs)

Schmitt trigger, negative-going

threshold (All digital inputs)

Hysteresis, Schmitt trigger

Input Current

Output Low Voltage

Output High Voltage

SW Switch on resistance

LED drive current

2.4V < DVCC < 3.6V

3.6 < DVCC <5.5V

V_T-

0.65

0.16

V_hys

V_T+

3.6V < DVCC <5.5V

V_T-

0.9

0.17

-10

µA

Ω

3.6V < DVCC <5.5V

V_IN= DVCC or GND

2K to DVCC

V_hys

I_IN

0.15

V_OL

V_OH

R_SW

I_LED

I_PEAK

2K to Ground

DVCC-0.3

DVCC = 3.0V

.15

.19

.25

100

.50

.32

115

DVCC=3.0V, @ 25°C

V_LED> 0.5V

Primary Peak Current

OVS = 11

OVS = 10

OVS = 01

OVS = 00

1.20

1.16

1.12

1.10

1.23

1.19

1.15

1.12

1.26

1.22

1.18

1.14

V_TRIP

Output Voltage Trip Point

MX881

7/30/07

Drawing No. 088109

www.claremicronix.com

MX881

IXYS

AC Characteristics

Junction temperature range 0 to + 115°C

Symbol

Parameter

Condition

Min

Typ

Max

Unit

CHARGE High to Beginning of

Charge Cycle

T_START

110

µS

CHARGE Low to End of Charge

Cycle

T_END

100

CL = 6.8nF, 10% to

90%

CL = 6.8nF, 90% to

10%

T_IGBT-ON

T_IGBT-OFF

FLASH High to IGBTGATE High

FLASH Low to IGBTGATE Low

T_LED-ON

T_LED-OFF

LED_EN High to Iout > 90mA

LED_EN Low to Iout < 1mA

TBD

µS

Control Register

The MX881 control register is a 5 bit register that allows the user to program the maximum output

voltage and the maximum average battery current during the charge cycle. Table1 shows how the bits in

the control register are assigned. ABC(2:0) are used to set the average battery current and OVS(1:0) are

used to set the output voltage selection reference.

Table 1 – Control Register

BIT:

Control:

OVS1

OVS0

ABC2

ABC1

ABC0

Output Voltage Selection

The MX881 limits the high voltage placed on the external capacitor by comparing a divided down version

of the secondary flyback voltage to an internal voltage. This internal voltage is programmable to 4

discrete values to allow the user to change the flash energy. The external voltage divider ratio needed to

obtain 330V maximum output voltage should be 269 to 1. This external resistor divider network is also

used to form a low pass filter with an internal capacitor so it is important that the equivalent resistance of

the voltage divider network be 3K ohms. Table 2 shows the internal reference values used for possible

values of the capacitor charge voltage. The default value is 11.

Table 2 - Output Voltage Selection

OVS Value (Binary) Reference Voltage (V_TRIP

)

Capacitor Voltage

1.23

1.19

1.15

1.12

330

320

310

300

MX881

7/30/07

Drawing No. 088109

www.claremicronix.com

MX881

IXYS

Average Battery Current

The 3 bits (ABC2 – ABC0) of the control register are used to program the maximum average battery

current during a charge cycle. The MX881 does this by limiting the minimum off time during a switching

cycle. The off time compensates for variation of the battery voltage so that the average current is

independent of battery voltage. The default value of ABC is 101. With the default value of ABC, the

average battery current control circuits are disabled for maximum efficiency, and the maximum battery

current is approximately 220mA. The average current versus the output voltage is shown in Figure1.

The battery current peak value is preset internally to 0.7A. This current must be averaged by placing an

external bypass capacitor from VCC to ground. A 10uF capacitor is recommended for good current

smoothing and averaging.

Figure 1 - Average Battery Current

Average Battery Current Setting of 50mA (ABC = 000)

VCC = 3.0V

VCC = 5.5V

100

200

300

400

MX881

7/30/07

Drawing No. 088109

www.claremicronix.com

MX881

IXYS

Average Battery Current Setting of 100mA (ABC = 001)

140

120

100

VCC = 3.0V

VCC = 5.5V

100

200

300

400

Average Battery Current Setting of 150mA (ABC = 010)

200

150

100

VCC = 3.0V

VCC = 5.5V

100

200

300

400

MX881

Drawing No. 088109

7/30/07

www.claremicronix.com

MX881

IXYS

Serial Interface

The MX881 has a 4 wire serial interface that is capable of operating in two modes: I²C or SPI. Both

modes transfer 8 bits of information but only 5 bits are actually used to set the internal control register.

Table 3 - Interface Modes

ISEL

Active Interface

Standard I²C slave only serial interface

Standard 3-wire SPI

I²C Bus Interface

The I²C interface (follows the standard bus protocol and timing as defined by Philips). For complete

information on this bus, refer to

www.semiconductors.philips.com

The MX881 acts as a slave device on the I²C bus and is compatible with both the HS (High Speed)

Mode and Fast Mode formats. Its primary function is as a receiver, receiving data from a master device

that is used to set a single 5 bit register that determines the average battery current and the output

voltage. It will act as a transmitter after receiving a read command. During a read, the register data will

be output onto the I²C bus. When receiving a non-broadcast message, the MX881 will respond with an

acknowledge bit, in which it pulls the data bus low at the appropriate time. Data packets begin with the

Master issuing a START command (S) and end with the Master issuing a STOP command (P). A Restart

command is simply another START command that is issued before a STOP command. Note that with

START and STOP commands that SDATA transitions while SCLK is high. Conversely, for all other bits,

SDATA is only allowed to transition while SCLK is low.

Figure 2 - I²C Sequences

SDA TA

T_I2C-CP

T_I2C-CS

T_{I2C-S C}

T_I2C-DS

T_I2C-DH

T_{I2C-P C}

SCLK

DA TA is stable during high period

of SCLK

STA RT

STOP

Shaded boxes represent bits

sourced by the MX889.

Unshaded boxes represent bits

sourced by the master .

Write Sequence

Overview

Slave Address

Data Byte - Written to control

The slave address is internally

fixed to 0111111 b.

Status

Read

Sequence

Slave Address

Data Byte - Register contents

placed on bus by MX889

Slave address is 0111111b.

MX881

Drawing No. 088109

7/30/07

www.claremicronix.com

MX881

IXYS

To write to the MX881 register, the master device will first issue a Start Bit. It will then transmit a 7-bit

address. In the MX881, the address is internally set to 0111111b. If the address in the message

corresponds to the address of the MX881, the device will issue an acknowledge. The master will send 8

bits of data. These 8 bits will be written into the control register. Another Acknowledge will follow. The

write sequence is illustrated in Figure 2.

To read the control register the master issues a read command by setting the R/Wn bit. The master will

then tri-state the data bus while the MX881 outputs data. See the example in Figure 2.

3-Wire SPI (Serial Peripheral Interface)

A standard 3-wire bi-directional serial interface is available (Figure 3). The interface signals are the serial

clock: SCLK, the serial data line: SDATA, and the serial chip enable: SCEn. SDATA is bidirectional.

In write mode, the microcontroller is writing to the MX881 control register. Each packet sent contains an

8-bit command followed by 8 bits of data to be written into the register.

When SCEn goes low, the rising edge of SCLK clocks in 8 bits, MSB first. At the end of the first

transmission byte, the MX881 determines whether the first byte is a recognized command. The MX881

only recognizes one write command “00011110”. If the command is recognized, the next byte clocked

into the MX881 will be written into the control register. This sequence is illustrated in Figure 3.

In read mode, a command is received which tells the MX881 to output the control register contents. The

MX881 only recognizes one read command: “01011110”. If the correct command is recognized, the

MX881 will output 8 bits of data beginning on the first falling edge of SCLK after the rising edge of SCLK

in which the last transmission bit was clocked in. In this manner, the first control register bit will be

available to the microcontroller on the next rising edge of SCLK. SCEn must remain low while the

MX881 is outputting data, going high after the MX881 has output the last bit. While the device is

outputting data, the microcontroller must stop driving the SDATA line so that the MX881 can drive the

data onto this bus. This sequence is also illustrated in Figure 3.

Table 4 - Serial Interface Timing

Symbol

T_CYCS

T_HI, T_LO

T_DS

T_DH

T_SS

T_SH

T_ACCS

T_OHS

T_{I2C_CS}

T_{I2C_SC}

T_{I2C_DS}

T_{I2C_DH}

T_{I2C_CP}

T_{I2C_PC}

Parameter

Cycle Time

Pulse Width

Data Setup Time

Condition

Min

250

Max

Units

Data Hold Time

SCEn Setup Time, Write

SCEn Hold Time, Write

Read Access Time

Read Output Disable Time

I²C Clock High to Start Bit

I²C Start Bit to Clock Low

I²C Data Valid to Clock High

I²C Clock Low to Data Change

I²C Clock High to Stop Bit

I²C Stop Bit to Clock Low

C_L= 100pF

MX881

Drawing No. 088109

7/30/07

www.claremicronix.com

MX881

IXYS

Figure 3 – 3-WIRE SPI

SCEn

SCLK

SDATATo

MX881

WriteCycle

SCEn

T_F

T_SS

T_HI

T_DH

T_CYCS

SCLK

SDATA

T_DS

T_LO

WriteCycleTiming

SCEn

SCLK

SDATATo

MX881

SDATA

From

MX881

Control

ReadCycle

SCEn

SCLK

T_ACCS

T_OHS

SDATA

ReadCycleTiming-Detailed

MX881

Drawing No. 088109

7/30/07

www.claremicronix.com

MX881

IXYS

Layout Notes

LDT565620ST-201

BAV23S

VPRI

VCC

VHV

VSEC

1.0uF 10uF

133K, 1%

22uF/350V

137K, 1%

SCEn

ISEL

CHARGE

FLASH

SCEn

ISEL

SDATA

CHARGE

FLASH

LSEC

SCLK

LED_EN

DONE

DVCC

VFB

LED_EN

DONE

DVCC

PROG

VFB

1K, 1%

VCC

LED

VCC

LED

IGBTGATE

.1uF

MX881 16 PIN DFN

.1uF

VCC

MX881

Drawing No. 088109

7/30/07

www.claremicronix.com

MX881

IXYS

Layout Notes:

•

Parasitic capacitance on node VSEC or VPRI will cause loss of efficiency. Keep wires on this

node as short as possible.

•

Parasitic inductance on the transformer connections can cause overshoot during switching that

could damage the part. Keep connections from the capacitors and MX881 to the transformer

short.

•

Also keep the connection from pin 2 of D1 to C3 as short as possible.

The VFB node is sensitive to coupling from T1 and the VSEC node. The VSEC node ramps to

over 300 volts in just a few nano-seconds. Keep R1, R2, and R3 as far from T1 as possible. If

possible, shield resistors by placing on the other side of the board from T1.

VCC should be well bypassed to average charge current to the battery and reduce noise to

analog circuits within MX881.

VFB is a very fast and short pulse. Keep VFB connection to R7 short to minimize capacitance on

this node. If VFB has too much capacitance, the feedback voltage may be filtered so that the

output voltage does not stop at 330V but continues to a much higher voltage.

A good ground plane is extremely important. Large pulse currents of 0.7 amps will be flowing in

the ground. The large bottom pad of the MX881 is the only ground pad and requires a low

impedance return to C1, C2, and R7.

•

The ground plane must have adequate clearance from high voltage nodes VHV and VSEC to

avoid arcing. Also, the node connecting R1 to R2 will be at approximately 170V.

R1 and R2 must be at least 1206 size surface mount to withstand 200V each.

Transformer

For 330V charger, the transformer should have a turns ratio of approximately 10 to insure that the fly-

back voltage on the primary side of the transformer does not damage the power switch internal to the

MX881. The fly-back voltage should be equal to the output voltage divided by the turns ratio plus the

VCC supply voltage. The fly-back voltage will be greater than this due to the energy stored in the

transformer leakage inductance. The actual voltage will depend on the transformer leakage inductance

and the parasitic capacitance of the circuits and layout.

The MX881 is designed to work with a transformer having a primary inductance of approximately 10µH.

Larger values are acceptable as long as leakage inductance is small. Smaller primary inductance values

may cause feedback pulses that are too short and lead to higher than expected output voltage.

IXYS Corporation makes no representations or warranties with respect to the accuracy or completeness of the contents of this

publication and reserves the right to make changes to specifications and product descriptions at any time without notice. Neither

circuit patent licenses nor indemnity are expressed or implied. Except as set forth in IXYS’ Standard Terms and Conditions of Sale,

IXYS Corporation assumes no liability whatsoever, and disclaims any expressed or implied warranty, relating to its products

including, but not limited to, the implied warranty of merchantability, fitness for a particular purpose, or infringement of any

intellectual property right

MX881

7/30/07

Drawing No. 088109

www.claremicronix.com

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Santa Clara, CA 925054

Tel: 408-982-0700

Fax: 408-496-0670

e-mail:sales@ixys.net

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Tel: 44 1249 444524

Fax: 44 1249 659448

sales@ixys.co.uk

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Fax: 1-949-831-4628

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SALES OFFICES AMERICAS

Eastern Region

[Eastern North America, Mexico, South America]

IXYS Corporation

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Tel: 508-528-6883

Fax: 508-528-4562

wgh@ixys.net

Check the IXYS Website for the local sales

office nearest you. (www.ixys.com)

Central Region

[Central North America]

IXYS Corporation

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Tel: 724-836-8530

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European Headquarters

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Edisonstrasse 15

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Tel: 49-6206-503203

Fax: 49-6206-503286

marcom@ixys.de

IXYS cannot assume responsibility for use of any circuitry other than circuitry

entirely embodied in this IXYS product. No circuit patent licenses nor indemnity

are expressed or implied. IXYS reserves the right to change the specification and

circuitry, without notice at any time. The products described in this document are

not intended for use in medical implantation or other direct life support

applications where malfunction may result in direct physical harm, injury or death

to a person.

Specification: MX881

MX881

7/30/07

Drawing No. 088109

www.claremicronix.com

MX881R [IXYS]

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