AS3645 austriamicrosystems, AS3645 Datasheet - Page 11

• Manufacturer Part Number: AS3645
• Description: 1000/720ma Ultra Small High Efficient Single/dual Led Flash Driver With Safety Features
• Manufacturer: austriamicrosystems

AS3645
Datasheet - D e t a i l e d D e s c r i p t i o n
Protection and Fault Detection Functions
The protection functions protect the AS3645 and the LED(s) against physical damage. In most cases a register bit is
set, which can be readout in I
parallel interface mode the fault bits are cleared when the device enters shutdown mode.
Overvoltage Protection
In case of no or a broken LED(s) at the pin LED_OUT and an enabled DCDC converter, the voltage on VOUT rises
until it reaches V
current sources are disabled and the bit
DCDC Inductor Peak Current Limitation
To limit the maximum current from the battery, the DCDC converter limits its current through the coil to I
a single cycle I
shorted coil is assumed. If this condition is detected, the DCDC is stopped, the current sources are disabled and the
bit
Short Circuit Protection
After the startup of the DCDC converter, the voltage on LED_OUT is continuously monitored and compared against
V
sources are disabled and the bit
Indicator LED open/short Detection
After the indicator current source is enabled and if the voltage on pin IND_OUT stays below V
cator LED is assumed. Then the bit
If the current through the indicator LED stays below I
rent source is not disabled
Overtemperature Protection
The junction temperature of the AS3645 is continuously monitored. If the temperature exceeds T
stopped, the current sources are disabled and the bit
enabled unless the junction temperature drops below T
Flash Timeout
If the flash is started
stopped and the flash current source (on pin LED_OUT) is disabled. In I
the STROBE input
is set.
Supply undervoltage Protection
If the voltage on the pin VIN (=battery voltage) is or falls below V
mode all registers are set to their default state.
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LEDSHORT
fault_coil_peak (see page 23)
2. To avoid erroneously disabling of the indicator current source due to short voltage drops on the supply.
3. In I
4. Can be adjusted in I
5. In parallel interface mode, after VIN rises above V
in parallel interface mode by setting SCL/EN1=1 and SDA/EN2=1
EN2=0 and TORCH=0 before accepting any inputs. This avoids oscillations effects for low batteries.
2
. If the voltage stays below V
C mode see section
LIMIT
VOUTMAX
(strobe_on
is reached and afterwards (still in the same cycle) the current through the coil reaches zero, a
3
a timeout timer is started in parallel. If the flash time exceeds t
(overvoltage condition). If this condition is detected, the DCDC converter is stopped, the
2
.
2
C mode
2
C mode. In I
= 1 and
Flash Strobe Timings (see page
fault_led_short (see page 24)
is set.
fault_ind_led (see page 24)
strobe_type
fault_ovp (see page 24)
LEDSHORT
2
C mode, the fault bits are cleared by a I
, the DCDC is stopped (as a shorted LED is assumed), the current
= 1, see
IND_OUTOPEN
fault_overtemp (see page 24)
Revision 1.6
OVTEMP
UVLO
Figure 22 on page
, the AS3645 waits for the pins SCL/EN1=0, SDA/
-T
is set.
UVLO
is set and the indicator current source is disabled.
OVTEMPHYST
is set.
16),
, the register bit
, the AS3645 is kept in shutdown state
2
C mode and if the flash duration is defined by
.
17) the bit
fault_ind_led
2
is set. The driver cannot be re-
FLASHTIMEOUT
C readout of the fault register. In
fault_timeout (see page 24)
INDSHORT
is also set, but the cur-
OVTEMP
4
, the DCDC is
, a shorted indi-
LIMIT
, the DCDC is
5
. If within
and in I
11 - 33
2
C