View AT1450_1061775.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC
Features
* 2.5 to 13 V supply voltage operating range. * Low current consumption: 6 mA in operation, * 20 kHz to 1 MHz operation frequency range. * Provides a fixed output current with minimal supply voltage fluctuations by using an external resistor to set the output current. * Totem-pole output. * Built-in soft start circuit. * Built-in auto-discharge function.
General Description
The AT1450 is a single-channel PWM control IC for Photoflash capacitor charger with soft start function and auto-discharge circuit. Adjustable soft start is programmed with an external capacitor on SS pin.
Applications
*Digital Still Cameras flash unit
Block Diagram
Aimtron reserves the right without notice to change this circuitry and specifications.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 1
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC
Pin Configuration
Ordering Information
Part number AT1450S AT1450S_Green Package SOP8 SOP8,Green Marking AT1450S AT1450S, date code with one bottom line
Pin Description
Pin No. Symbol I/O Description
1 2 3 4 5 6 7 8
INSS VCC BR/CTL OUT GND OSC FB
I -- -- I O -- -- O
Error amplifier inverting input Soft start setting capacitor connection Power supply Output current setting Totem-pole type output Ground Capacitor and resistor connection pin for setting the oscillation frequency Error amplifier output
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 2
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC
Absolute Maximum Ratings
(Ta=+250C)
Parameter Power supply voltage Output source current Output sink current Allowable dissipation Operating temperature Storage temperature
ESD Classification
Symbol VCC IO+ IOPD PD TOP TSTG
Condition -- -- -- SOP-8, Ta +25C TSSOP-8, Ta +25C -- --
MIL-STD-883
Rated Value Min. Max. -- 15 -- -50 -- 50 -- 570 -- 430 -30 +85 -55 +125
Class 2
Unit V mA mA mW mW 0 C 0 C
* : When mounted on a 10 cm square double-sided epoxy board WARNING: Do not exceed these ratings. IC devices can be permanently damaged by stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings.
Recommended Operating Conditions
(Ta=+250C)
Parameter
Symbol
Values
Unit
Min. Typ. Max. Power supply voltage VCC 2.5 -13.5 Error amplifier input voltage VI -0.2 -1.0 BR/CTL pin input voltage VBR -0.2 -VCC Output source current IO+ -20 -- Output sink current IO--40 SS pin capacitance CPE -0.1 - Phase compensation capacitance CP -0.1 - Output current setting resistance RB 150 390 5000 Timing resistance RT 1.0 3.0 10.0 Timing capacitance CT 100 270 10000 pF Oscillation frequency fOSC 10 500 1000 kHz Operating temperature TOP -30 +25 +85 C WARNING: Recommended operating conditions are normal operating ranges for the IC device. All the device's electrical characteristics are warranted for operation within these ranges. Use IC devices only within the recommended operating conditions. Operation outside these ranges may adversely affect the reliability and can result in device failure.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 3
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC Electrical Characteristics
(VCC=+3.0V, Ta=+250C)
Parameter VCC Under voltage Reset voltage for Lockout falling Vcc. OUT (U.V.L.O.) remains off if Vcc is below this level. Startup voltage for rising Vcc. Soft start Charging current Voltage at soft start completion Invalid threshold voltage of SS Oscillation frequency
Symbol VR
Condition
Values Min. Typ. Max. -- 2.24 --
Unit V
-VTH ISS VSS VSS=0V --fOSC fV fT VT VTV VTT IB AV BW VOM+ VOM_ IOM+ IOM_ TDUTY VOH1 VOH2 VOL1 VOL2 RT=3k, CT=270pF VCC=2.5V to 13.5V Ta =-300C to 850C VFB = 450mV VCC=2V to 13.5V Ta = -300C to 850C VIN = 0V -AV = 0 dB -2.4 2.5 2.6 V
-1.5 -1.0 -0.7 A 1.000 1.150 1.260 V -400 --480 --0.8 500 2 5 500 5 1 -600 10 -520 20 -V kHz % % mV mV %
Sawtooth waveform oscillator (OSC) Frequency input Stability Frequency variation with temperature Input threshold Voltage VT input stability VT variation with Temperature Input bias current Voltage gain Frequency bandwidth Maximum output voltage range Output source current Output sink current Maximum duty cycle
Error amplifier
VFB = 450mV RT=3.3k, CT=270pF fOSC = 500KHz RB= 390, IO= -15 mA RB= 750, VCC = 3.0V IO= -10 mA RB= 390, IO= -15 mA RB= 750, VCC = 3.0V IO= -10 mA RB= 390, VO = 0.9V RB= 390, VO = 0.3V -RB= 390 --
Idle period adjustment section
-1.0 -0.2 70 100 -6 0.78 0.87 -- 0.05 --40 24 40 -85 1.0 0.8 --1.2 1.0 0.1 0.1
1.0 A 145 V/V -- MHz -V 0.2 V -24 A -- A 87 % --0.2 0.2 V V V V
Output voltage Output section
Output current Setting section/ Control section
Output source current Output sink current Pull down resistance Pin voltage Input off condition Input on condition Pin current range
IO+ IORO VBR IOFF ION IBR
--40 -30 mA 40 70 -mA 20 30 40 0.10 0.19 0.25 V -20 -0 A ---45 A -1.8 --0.1
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 4
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC
Stand-by current Entire device Average supply current ICCS ICC BR/CTL pin open or VCC RB= 390, VCC =2.5~13.5V ---6 200 A
10.0
Timing Chart
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 5
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC CH1:SS CH2:OUT Soft-Start and Auto Dis-Charge function
CSS=1F
CSS=10F
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 6
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC
Typical Application Schematic
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 7
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC
Functional Description
Soft Start At power-on, the AT1450 enters the soft-start mode to prevent current spike and overshoot. The capacitor CS is charged from 0.2V at a constant current of 1A. The soft-start time for the duty cycle
t S ( s ) = 0.8 x CS ( F )
Setting Oscillating Frequency The oscillator circuit generates a triangular sawtooth wave with a peak of 0.8V and a trough of 0.1V using the timing capacitor (CT) and the timing resistor (RT) that are connected to the OSC pin. This oscillator can provide oscillating frequency in the range from 20KHz to 1MHz. The waveform of the OSC pin is shown as Figure 2.
Figure 2 Oscillator Waveform The cycle (T) can be determined as follows:
VX = VHe
VX ) VH T = -CT x RT x log e (0.1 / 0.8) = 2.1 x CT x RT [s ]
- t CT x RT
t = -CT x RT x log e (
Switching Regulator Function (1) Reference voltage circuit A temperature-compensated reference voltage (~1.25V) is generated by the reference voltage circuit from the voltage supplied by the power supply pin (pin 3). The circuit also sets the idle period besides providing the reference voltage for the switching regulator. 2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 8
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC
(2) Error amplifier The error amplifier detects the output voltage of the switching regulator and sets the PWM control signal. The voltage gain is fixed. The system is made stable by connecting a phase compensation capacitor to the FB pin (pin 8). (3) PWM comparator The voltage comparator includes one inverting and three non-inverting inputs. The comparator is a voltage to pulse width converter that controls the ON time of the output pulse depending on the level of input voltage. The output level remains high when the sawtooth wave is lower than the error amplifier output voltage, the soft start setting voltage, and the idle period setting voltage. (4) Output circuit The output circuit can drive an external NPN transistor directly and has a totem pole configuration. The value of the ON/OFF current can be set by a resistor connected to the BR/CTL pin (pin 4). Stand-by mode (supply current 1A or less) can be set by connecting the BR/CTL pin (pin4) to VCC or by making the pin open. (5) Under-Voltage Lockout (UVLO) Transients during powering on or instantaneous glitches in the supply voltage can cause the control IC to malfunction and damage the system. To prevent malfunction at low input voltage, the circuit compares the supply voltage to the internal reference voltage to detect a low input voltage. Once detected, the circuit sets the output pin low. To cancel the status, set VCC below the reset voltage VR (0.9V) and then set VCC up to the recommended operation range and the latch will be restored to operate normally.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 9
AT1450
Preliminary Product Information Photoflash Capacitor Charger for DSC
Small Outline
8-pin Plastic SOL
SYMBOL A B C D E F H J K M L e1
INCHES MIN MAX 0.188 0.197 0.149 0.158 0.228 0.244 0.050 BSC 0.013 0.020 0.004 0.010 0.053 0.069 0.011 0.019 0.007 0.010 0.016 0.050 0.150 REF 450 0 80 0
MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 5.80 6.20 1.27 BSC 0.33 0.51 0.10 0.25 1.35 1.75 0.28 0.48 0.19 0.25 0.40 1.27 3.81 REF 450 0 0 80
NOTES -
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 10

▲Up To Search▲

Price & Availability of AT1450

	To Download AT1450 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .