AIMTRON AT1454AM-GRE

AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Feature
• 2.5V to 5.5V Supply Voltage Operating
•
•
•
•
•
•
•
•
•
•
•
Range.
Low Current Consumption:1mA in operation.
Adjustable Output Voltage.
Adjustable Switch On-Time.
Charge Complete Indicator.
Built-in IGBT Driver.
Soft-Start Circuitry.
Thermal Protection
Charges Any Size Photoflash Capacitor.
AT1454 with Auto-Refresh Function.
AT1454A/B without Auto-Refresh Function.
Small 10-lead MSOP Package.
Application
• Digital / Film Camera Flash
• PDA / Cell Phone Flash.
Description
The AT1454 series is a charger IC for Photoflash
capacitor with soft-start function, an IGBT driver
for igniting flash tube, adjustable output voltage
and adjustable switch on-time to perform energy
transition on each charge cycle. The output voltage
can be adjusted by simply changing the turn ratio
of transformer. AT1454B is sensed by voltage
divider connecting to the anode of the rectifying
diode. The voltage sensing path is cut off when
charging function to be completed to maintain
minimum output voltage decay.
The device allows user to control automatic refresh
rate on Charge pin. While the Ready pin signals
that the capacitor is fully charged.
AT1454/AT1454A/AT1454B
MSOP-10 package.
is
available
in
Block Diagram
Aimtron reserves the right without notice to change this circuitry and specifications.
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
1
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Pin Configuration
1
0
9
8
7
6
4
5
1454
1
2
3
Ordering Information
Part number
AT1454M_GRE
AT1454AM_GRE
AT1454BM_GRE
Package
MSOP-10 , Green
MSOP-10 , Green
MSOP-10 , Green
Marking
AT1454, Date code with one bottom line
AT1454A, Date code with one bottom line
AT1454B, Date code with one bottom line
*For more marking information, contact our sales representative directly
Pin Description
Pin N0.
Symbol
1
CHARGE
2
FB
3
TRIGGER
I/O
I
I
I
4
ISEC
I
5
GND
P
6
LX
I
7
8
9
10
DRIVER
VCC
READY
Rsense
O
P
O
I
Description
Charge enable input
Comparator input
IGBT Trigger signal input.
Detecting transformer secondary current. Take care to use the
correct phasing of the transformer.
Ground
Power MOSFET N-channel Drain. Connect Primary transformer.
Take care to use the correct phasing of the transformer.
IGBT Driver output.
Power supply.
Charge ready open drain output.
A resistor from Rsense to VCC or VBAT sets the constant On-time.
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
2
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Absolute Maximum Ratings*1
Parameter
Rated Value
Unit
VCC , TRIGGER , DRIVER , CHARGE , FB and READY voltage
-0.3 to +6.0
V
LX voltage
+30
V
SEC Current
±300
mA
Continuous power dissipation (MSOP-10,Ta=+25 C)
555
mW
Junction Temperature
125
℃
Lead
260
℃
-40~125
℃
HBM
2
KV
MM
200
O
Temperature (Soldering 10 sec)
Storage Temperature
ESD Susceptibility*2
V
1. 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 in the operational sections of the specifications is not implied. Exposure
to absolute maximum rating conditions for extended periods may affect device reliability.
2. Device are ESD sensitive. Handling precaution recommended. The Human Body model is a 100pF
capacitor discharged through a 1.5KΩ resistor into each pin.
Recommended Operation Conditions
Parameter
Power supply voltage
Operating temperature
LX voltage
Symbol
VCC
Top
VLX
Min.
2.5
-30
VCC
Values
Typ.
―
+25
―
Max.
+5.5
+85
28
Unit
V
℃
V
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
3
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Electrical Characteristics
(VCC=3.3V, Ta=+25℃, unless otherwise noted)
Parameter
Symbol
Input operating voltage
VCC
Input under-voltage threshold
VUVLO
Test Condition
VCC falling
VCC UVLO hysteresis
Min.
Typ. Max. Units
2.5
―
5.5
V
―
2.1
―
V
―
100
―
mV
1.08
1.10
1.12
V
Feedback voltage
VFB
Ta=+25℃
Shutdown current
IOFF
CHARGE pin=GND
―
0.01
1
µA
Quiescent Current
Icc
No Switching , FB=1.2V
―
40
60
µA
Primary side current limit
Secondary side transit current
ILX(MAX)
Isec
―
2.5
―
A
―
5
―
mA
LX Switch On-Resistance
RLX(ON) ILX=2A
―
0.17
―
Ω
LX Leakage Current
ILC
VLX=28V
―
0.01
6
µA
IGBT Driver Rising time
tr
VCC=3.3V, CL=3900pF
―
55
―
ns
VCC=3.3V, CL=8200pF
―
90
―
ns
IGBT Driver Falling time
tf
VCC=3.3V, CL=3900pF
―
55
―
ns
VCC=3.3V, CL=8200pF
IGBT Trigger signal high
IGBT Trigger signal low
Charge input voltage high
VON
Charge input voltage low
VOFF
0.1V hysteresis
Charge pin Bias current
VCHARGE =3.3V
Ready output signal high
100kΩ from Vcc to Ready
pin
33µA into Ready pin
Ready output signal low
Thermal Shutdown
―
90
―
ns
0.45Vc
c
―
―
V
―
―
0.3Vcc
V
0.9
―
―
V
―
―
0.8
V
―
3
―
µA
―
3.27
―
V
―
1.0
0
mV
―
140
―
℃
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
4
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Timing Chart
Vcc
Trige
READY
VOUT
CHARGE
Charge On
Timing
Shutdown
Power OFF
Timing
Charging
Auto charge to Refresh
Storbe
AT1454 Auto-Refresh Mode
Vcc
Trige
READY
VOUT
CHARGE
Charge On
Timing
Shutdown
Power OFF
Timing
Charging
Toggling CHARGE to Refresh
Storbe
1.uP Detected READY pin Low ->High(Charge Complete)
-->allow enter refresh mode or strobe tube
2.Use uP to delay Photoflash Capacitor self-discharge time Ts
3.Toggling CHARGE pin high->low->high, force the IC into refresh
charging mode.
AT1454A/B Charge Toggle-Refresh (Soft-ware control)Mode
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
5
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Typical Operating Characteristics
VLX & Primary Current ,Time(1us/Div) [CH2:VLX; CH4:IPRI]
Vout=100V
VLX(5V/Div)
IPRI(1A/Div)
Vout=100
VLX & Primary Current ,Time(1us/Div) [CH2:VLX; CH4:IPRI]
Vout=300V
VLX(10V/Div)
IPRI(1A/Div)
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
6
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
VLX & Secondary Current ,Time(1us/Div)
[CH2:VLX; CH4:ISEC]
Vout=100V
VLX(5V/Div)
ISEC(50mA/Div
Charging waveform without auto-refresh function , Time(1 s/Div)
VCC=3.3V, VBAT=4.2V, C=120uF
CH1:READY CH2:CHARGE CH3:Output Voltage
CH4:Input Current
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
7
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Charging waveform with auto-refresh function , Time(1 s/Div)
VCC=3.3V, VBAT=3.0V, C=47uF
CH1:READY CH2:CHARGE
CH3:Output Voltage
CH4:Input Current
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
8
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Application Circuit
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
9
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
10
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
11
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Application Information
AT1454 series is designed to precise control of switching current to charge photoflash
capacitors quickly and efficiently. When the Charge pin is first driven high, a one shot
set SR latches in the correct state. The built-in power MOSFET turns on and primary
current ramps up linearly according to VBAT and primary inductance. Comparator
monitors the switch On-time and when the switch on-time reaches limit value,
MOSFET is turned off. During this phase, stored energy of primary transformer is
delivered to the photoflash capacitor via the secondary and diode. The secondary
current is decreased linearly at a rate determined by the secondary inductance. The
secondary current is monitored by the Isec pin. When the secondary current drops
below 10mA, the fires a one shot will turn on MOSFET. The charging cycle repeats to
deliver power to the output.
AT1454 series can adjust external resistance RSENSE to set N-MOS switch on-time, but
switch on-time value must match with electrical characteristic of transformer. It is
usually equal to or less than saturation current of transformer otherwise transformer
will be saturated. Therefore, efficiency will be reduced.
The output voltage is detected by a voltage divider connecting to output capacitor.
When the output voltage reaches the desired voltage set by resistive voltage-divider,
comparator output goes high which resets the master latch and disable the charging
block. The N-channel MOSFET is turned off pulling the Ready pin high, indicating
that the part has finished charging. Power delivery can be restarted automatically
when feedback voltage is less than 90% of reference voltage. Power delivery can only
be restarted by toggling the Charge pin. The Charge pin gives full control of the part
to the user. The IGBT buffer will provide a sufficient current to drive IGBT to ignite
flash tube.
Transformer Design
The Fly-back transformer is a key element for AT1454 series. It must be designed
carefully and checked that it does not cause excessive current or voltage on any pin of
the part. The first transformer parameter that needs to be set is the turns ratio N,
should be high enough so that the absolute maximum voltage rating for the NMOS
drain to source voltage is not exceeded. Choose the minimum turns ratio according to
following formula:
N MIN ≥
VOUT
V DS ( MAX ) − V BAT
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
12
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Vout: Target Output Voltage
VDS(MAX):Maximum drain to source voltage of NMOS.
Adjustable Output Voltage
The AT1454/1454A/B senses output voltage by a voltage divider connecting to output
terminal. R7 to (R8+R9) ratio determines the output voltage as shown in the
application circuit Figure 1. The feedback reference voltage is 1.1V. Calculate the
remaining resistors with following equations:
VOUT = V FB × (1 +
R8 + R9
)
R7
R8and R9 must be greater than 0805 size resistor for enduring secondary HV.
Rectifying Diode
The rectifying diode should be low capacitance type with sufficient reverse
recovery-voltage and forward current ratings. The peak reverse recovery-voltage that
diode is approximately:
VPK-R≅ VOUT + (N x VCC)
The peak current of the diode is simply:
IPK-SEC= IPK-PRI / N
Primary Inductance
A fly-back transformer needs to store substantial amounts of energy in the core during
each switching cycle. The transformer will generally require an air gap. The use of an
air gap in the core makes the energy storage. While the power switch is off, energy
transferred to the output capacitor is proportional to the primary inductance for a
constant primary current. The primary inductance needs to be equal or larger than a
certain minimum value to ensure that AT1454 series has adequate time to respond to
the fly-back waveform. The switch off time should be 500ns or larger for the AT1454
series. The minimum inductance can be calculated with the following formula:
500 × 10 −9 × VOUT
LPRI ≥
N × I PK − PRI
Vout: Target Output Voltage
N: Transformer Turns Ratio
IPK-PRI: Primary Peak Current
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
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3/24/2006 REV:1.2
Email: service@aimtron.com.tw
13
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Leakage Inductance and Parasitic Capacitance
The leakage inductance on the primary of the transformer results in the first spike
voltage when NMOS turns off. The spike voltage is proportional to the leakage
inductance. The spike voltage must not exceed the dynamic rating of the NMOS drain
to source voltage. It is important not to minimize the leakage inductance to a very
low level. Although this would result in a very low leakage spike, the parasitic
capacitance of the transformer will be high between windings. This will result in the
initial spike of current in the primary becoming excessively high while the NMOS
turns on. Therefore, trade off is necessary between leakage inductance and parasitic
capacitance.
Spike Voltage @Switching,Time(1us/Div)
Swing Current @Switching,Time(1us/Div)
VLX(5V/Div) , IPRI(1A/Div)
VLX(10V/Div) , IPRI(1A/Div)
Spike Voltage
CH1
Swing Current
CH2
CH1:VLX; CH2:Input Current
Transformer Secondary Capacitance
The total capacitance on the secondary of the transformer will severely affect the
efficiency of the circuit. Any secondary capacitance is multiplied by N2 when
reflected to the primary. Since this capacitance forms a resonant circuit with the
primary leakage inductance of the transformer. As such, both the primary leakage
inductance and secondary side capacitance should be minimized.
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
14
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Adjustable Input Current
The AT1454/1454A/B can adjust N-MOS switch on-time by a resistor connecting to
Rsense pin. This resistor determines the primary peak current and on-time of primary
N-MOS as the following equation:
I PK − PRI =
TON =
V BAT × 2 × 10 −6
25 KΩ
, V Rsense = V BAT (or , VCC ) ×
V Rsense × L PRI
R4 + 25 KΩ
I PK − PRI × L PRI
V BAT
where
LPRI: primary inductance (µH)
IPK-PRI: peak primary current (A)
R4: It is recommended several KΩ grade
If setting constant on-time by a resistor R10 is connected to VCC, then R4 resistor
need to remove from application circuitry. In this case, on-time is a constant. At
another topology, if R4 connect to VBAT to set constant on-time, then R10 need to
remove from application circuitry. However, on-time can change dependent on VBAT
because battery voltage level is different from full energy to low power. External
capacitor Css is connected to VCC and Rsense to perform soft-start function to reduce
inrush current on VBAT input current and avoid the internal switching noise.
VBAT
L1 33uH
/Option
VCC
R10
T1
ST-982610A
1:25
10uH/6.1mH
R4
C1
22u/6V3
Css
0.1uF
VCC
Rsense
LX
Isec
AT1454/AT1454A/AT1454B
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
15
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Auto-Refresh
AT1454 supports auto-refresh function required in some DCS application. When the
output capacitor is charged complete, the READY pin will goes high and Vout will
decrease slightly due to leakage current. The refresh block trip point is VFBx90%.
While the Vout is decreased to the refresh trip point, it enables the charge block,
disable the refresh block and pull low the READY pin. This cycle of recharge
operation will repeat again until charge pin is pulled low.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation in the AT1454 series.
When the junction temperature exceeds Tj=140 ℃, a thermal sensor activates the
thermal protection, which shuts down the IC, allowing the IC to cool. Once the device
cools down by 15 ℃, IC will automatically recover normal operation. For continuous
operation , do not exceed the absolute maximum junction-temperature rating of
Tj=130 ℃.
Prevent the Leakage of READY pin
VCC
CHARGE
READY
READY
If pull-high resistor of READY signal connect to Charge pin, then it can reduce power
consumption on pull-high resistor of READY during charge pin goes low.
Board Layout
The high voltage operation of the AT1454/AT1454A/AT1454B demands careful
attention to board layout. You will not get advertised performance with careless layout.
Keep the area for the high voltage end of the secondary as small as possible. Also note
the larger than minimum spacing for all high voltage nodes in order to meet
breakdown voltage requirements for the circuit board. Remember that lethal voltages
are present in this circuit. Use caution when working with the circuit.
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
16
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Outline
10-pin MSOP
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
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3/24/2006 REV:1.2
Email: service@aimtron.com.tw
17
AT1454/AT1454A/AT1454B
Preliminary Product Information
Photoflash Capacitor Charger for DSC
Reflow Profiles
Profile Feature
Average ramp-up rate
(TL to TP)
Preheat
-Temperature Min(Tsmin)
-Temperature Max (Tsmax)
-Time (min to max)(ts)
Tsmax to TL
-Ramp-up Rate
Time maintained above:
-Temperature (TL)
-Time (tL)
Peak Temperature(TP)
Time within 5°C of actual Peak
Temperature (tP)
Ramp-down Rate
Time
25°C
to
Peak
Temperature
Sn-Pb Eutectic Assembly
Large Body
Small Body
Pkg. thickness
Pkg. thickness
<2.5mm or Pkg.
≥2.5mm or Pkg.
3
volume
<350mm3
volume ≥350mm
3°C/second max.
Pb-Free Assembly
Large Body
Small Body
Pkg. thickness
Pkg. thickness
≥2.5mm or Pkg.
≥2.5mm or Pkg.
3
volume ≥350mm
volume ≥350mm3
3°C/second max.
100°C
150°C
60-120 seconds
150°C
200°C
60-180 seconds
3°C/second max.
183°C
60-150 seconds
217°C
60-150 seconds
225+0/-5°C
10-30 seconds
240+0/-5°C
10-30 seconds
6°C/second max.
6 minutes max.
245+0/-5°C
10-30 seconds
250+0/-5°C
20-40 seconds
3°C/second max.
8 minutes max.
*All temperatures refer to topside of the package, measured on the package body surface.
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
3/24/2006 REV:1.2
Email: service@aimtron.com.tw
18