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Technical content
The technical content of this austriamicrosystems datasheet is still valid. Contact information: Headquarters: ams AG Tobelbaderstrasse 30
8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0 e-Mail: ams_sales@ams.com Please visit our website at www.ams.com
1 General Description
flash/torch/assist (video/autofocus) and indicator mode. and simplifies production test procedures. over the -30ºC to +85ºC temperature range. Figure 1. Typical Operating Circuit
2 Key Features
3 Applications
4 Pinout
Figure 2. Pin Assignments (Top View) Table 1. Pin Description for AS3642
5 Absolute Maximum Ratings
Table 2. Absolute Maximum Ratings
- Depending on actual PCB layout and PCB used; for peak power dissipation during flashing see document
- PDERATE derating factor changes the total continuous power dissipation (PT) if the ambient temperature is not
6 Electrical Characteristics
+25ºC, unless otherwise specified. Table 3. Electrical Characteristics
1.26 VVIN-
Table 3. Electrical Characteristics (Continued)
Figure 3. I2C interface Timing Diagram
- Limited to max. 5V due to overvoltage protection circuit on pin VOUT
- Due to slope compensation of the current limit, ILIMIT changes with duty cycle - see Figure 16 on page 9.
- Due to the architecture (the supply of the AS3642 is connected to the output VOUT), the undervoltage lockout
- The logic input levels VIH and VIL allow for 1.8V supplied driving circuit (70%/30% of 1.8V)
- After this period, the first clock pulse is generated.
- A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the VIHMIN of the
SCL signal) to bridge the undefined region of the falling edge of SCL.
- A fast-mode device can be used in a standard-mode system, but the requirement tSU:DAT = to 250ns must then
tSU:DAT = 1000 + 250 = 1250ns before the SCL line is released.
7 Typical Operating Characteristics
Figure 4. DCDC Efficiency vs. VVIN Figure 5. Application Efficiency (PLED/PVIN) vs. VVIN Figure 6. ILED Startup (ILED_OUT=300mA) Figure 7. IVIN Startup (ILED_OUT=300mA) Figure 8. ILED Startup (ILED_OUT=51.6mA) Figure 9. VOUT / I LED_OUT ripple, ILED_OUT = 300mA
8 Detailed Description
frequency of 4MHz allows the use of tiny coils. Its output is connected to a flash LED by an internal current source.
- Flash mode (enabled by mode=11):
If SCL and SDA are L for more than tTIMEOUT, shutdown mode is automatically entered.
- Assist light mode (=video or torch light mode) (enabled by mode=10):
If SCL and SDA are L for more than tTIMEOUT, shutdown mode is automatically entered.
- Indicator light mode (enabled by mode=01):
- Shutdown mode (mode=00), SCL=0V, SDA=0V:
The DCDC and the current source is disabled and the AS3642 is configured to draw minimum current. Figure 16. AS3642 internal circuit
- The PWM modulation frequency is 31.25kHz to avoid audible noise on the external capacitors.
www.austriamicrosystems.com/AS3642 1.2-2 11 - 26 AS3642 Datasheet - Detailed Description Protection and Fault Detection Functions The protection functions protect the AS3642 and the LED(s) against physical damage. In most cases a register bit is set, which can be readout with the interface. The fault bits are cleared3 by a readout of the fault register. DCDC Overvoltage Protection In case of no or a broken LED at the pin LED_OUT and an enabled DCDC converter, the voltage on VOUT rises until it reaches VVOUTMAX (overvoltage condition) and the voltage across the current source does not reach regulation (VOUT-VLED < VILED_COMP). If this condition is detected, the DCDC converter is stopped, the current sources are dis- abled and the bit fault_ovp (see page 19)4 is set. DCDC Broken Coil Detection If the coil LDCDC is broken, the AS3642 is not powered by the pin SW connected to VOUT by the internal switch. Due to the protection diodes between SCL to VOUT and SDA to VOUT, the AS3642 can be powered through these diodes. The AS3642 detects this error condition by comparing the voltage on SCL and VOUT. If the voltage on VOUT is lower compared to the voltage on SCL, the AS3642 will ignore any I2C write commands. Therefore the application can simply detect this condition. Note: Due to the broken coil detection, the high levels of SDA and SCL should be always below the supply voltage. LED Short Circuit Protection After the startup of the DCDC converter, the voltage on LED_OUT is continuously monitored and compared against VLEDSHORT. If the voltage stays below VLEDSHORT, the DCDC is stopped (as a shorted LED is assumed), the current sources are disabled and the bit fault_led_short (see page 19) is set. Overtemperature Protection The junction temperature of the AS3642 is continuously monitored. If the temperature exceeds TOVTEMP, the DCDC is stopped, the current sources are disabled and the bit fault_overtemp (see page 19) is set. The driver cannot be re- enabled unless the junction temperature drops below TOVTEMP-TOVTEMPHYST. Flash Timer The duration of the flash is defined by the register flash_timer (see page 18). After the timer expires, the DCDC is stopped and the flash current source (on pin LED_OUT) is disabled. Supply undervoltage Protection If the voltage on the pin VOUT (=battery voltage) is or falls below VUVLO, the AS3642 is kept in shutdown state and in all registers are set to their default state. Note: During operation of the DCDC converter, the supply undervoltage protection will still monitor the DCDC output voltage only. Therefore the supply undervoltage protection will only monitor the battery voltage if the DCDC converter is switched off and the output capacitor is discharged down to the supply voltage. Wakeup Circuit - Power off detection In flash, assist light and indicator mode (register mode (page 18)=01, 10 or 11), if SCL and SDA are L for more than tTIMEOUT, shutdown mode is automatically entered. This feature automatically detects a power-off of the controlling cir- cuit driving SCL and SDA (VDD_I/F goes to 0V) - the internal circuit is shown in Figure 19: 3. Except overtemperature protection bit fault_overtemp: This bit can be cleared once the temperature drops below TOVTEMP-TOVTEMPHYST. 4. In indicator mode (mode=01) the register fault_ovpi s never set (the overvoltage protection is nevertheless operating) ams AG Technical content still valid
Figure 19. Device Shutdown and Wakeup open-drain I/O lines SDA and SCL. Data transfer may be initiated only when the bus is not busy. while the clock line is HIGH are interpreted as control signals. Both data and clock lines remain HIGH. A change in the state of the data line, from HIGH to LOW, while the clock is HIGH, defines a START condition. A change in the state of the data line, from LOW to HIGH, while the clock line is HIGH, defines the STOP condition. the HIGH period of the clock signal. The data on the line must be changed during the LOW period of the clock signal. There is one clock pulse per bit of data. information is transferred byte-wise and each receiver acknowledges with a ninth bit.
master device must generate an extra clock pulse that is associated with this acknowledge bit. enable the master to generate the STOP condition. Figure 20. Data Transfer on I2C Serial Bus
- Data transfer from a master transmitter to a slave receiver. The first byte transmitted by the master is the
byte. Data is transferred with the most significant bit (MSB) first.
- Data transfer from a slave transmitter to a master receiver. The master transmits the first byte (the slave
released. Data is transferred with the most significant bit (MSB) first.
- Slave Receiver Mode (Write Mode): Serial data and clock are received through SDA and SCL. After each
followed by the direction bit (R/W), which, for a write, is 0.
5 After receiving and decoding the slave address
write bit, the master transmits a register address to the AS3642. This sets the register pointer on the AS3642. The master may then transmit zero or more bytes of data, with the AS3642 acknowledging each byte received.
- The address for writing to the AS3642 is 60h = 01100000b
Figure 23. Data Read (Write Pointer, Then Read) - Slave Receive and Transmit
Table 4. Design Info Register Table 5. Version Control Register Table 6. Current Set Register
00 LED_OUT current is defined by ind_current,
01 LED_OUT current is defined by register 2, bits <7:3>
11 LED_OUT current is defined by register 2, bits <7:3>
0 Pulseskip operation is allowed for all modes -
00 I LED_OUT = 260mA
01 I LED_OUT = 280mA
10 ILED_OUT = 300mA
11 I LED_OUT = 320mA
- Before changing current_mode register, write 0xA1 to register 0x80h (password protection). This sequence is
Additionally do not change this register if the DCDC is operating.
- For currents above 320mA, the AS3642 will always enable pulseskip mode (register setting of freq_switch_on
Table 6. Current Set Register (Continued)
Table 7. Control Register
00 Shutdown mode
01 Indicator light mode with ind_current
10 Assist light mode2 with assist_current
external_strobe and ‘00’ to mode.
- Before changing mode register to 01, write 0xA1 to register 0x80h (password protection).
- Torch mode and assist light mode share the same operating mode and identical currents.
- Before changing external_strobe register to 01, write 0xA1 to register 0x80h (password protection).
Table 8. Fault Register
1 Junction temperature limit has been exceeded
1 A shorted LED is detected (pin LED_OUT)
1 An overvoltage condition is detected (pin VOUT)
Table 9. Register Map
9 Application Information
capacitors are required for input decoupling and should be located as close to the device as is practical. supply voltage. Larger capacitor values (C) may be used without limitations. Table 10. Recommended Input Capacitor Table 11. Recommended Output Capacitor Table 12. Recommended Inductor
If a different inductor is chosen, ensure similar DCR values and at least 0.7µH inductance at 0.9A input current. Use LED and optics as required by the system. between Loop1 and Loop2 and will not pass the ground plane) - see the ‘ground via’ in Figure 24. Table 13. Recommended LEDs Table 12. Recommended Inductor (Continued)
- Write 0x20 into register 0x03 (Control register) [Enable assist light with default 72mA].
- Read back7 register 0x03 - must return 0x20, otherwise LDCDC or I2C (SCL or SDA) is broken
- Write 0x00 into register 0x03 [Power off]
- Read register 0x04 (Fault register) - must return 0x00, otherwise the LED is open or shorted
- Alternative testing method: Instead of reading the in ternal registers, the current into the AS3642 can be
Table 14. How-to identify errors Table 15. I2C Programing Example - 500mA, 480ms flash pulse
Figure 26. 6pin WL-CSP Marking Figure 27. 6pin WL-CSP Package Dimensions The coplanarity of the balls is 40µm.
The devices are available as the standard products shown in Table 16. Note: All products are RoHS compliant and austriamicrosystems green. Table 16. Ordering Information
www.austriamicrosystems.com/AS3642 1.2-2 26 - 26 AS3642 Datasheet - Ordering Information Copyrights Copyright © 1997-2011, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, trans- lated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies. Disclaimer Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriami- crosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life- sustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location. The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the tech- nical data herein. No obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems AG rendering of technical or other services. Contact Information Headquarters austriamicrosystems AG Tobelbaderstrasse 30 Schloss Premstaetten A-8141 Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com/contact ams AG Technical content still valid