A8436EEJTR-T Allegro Microsystems Inc, A8436EEJTR-T Datasheet - Page 11

• Manufacturer Part Number: A8436EEJTR-T
• Description: IC PHOTOFLASH CHARGER 10-MLP
• Manufacturer: Allegro Microsystems Inc

Specifications of A8436EEJTR-T

• Applications: Photoflash Capacitor Charger
• Current - Supply: 1.3mA
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-WFDFN Exposed Pad
• Input Voltage: 5.5V
• No. Of Outputs: 1
• Supply Voltage Range: 3V To 5.5V
• No. Of Pins: 10
• Operating Temperature Range: -40°C To +85°C
• Termination Type: SMD
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 620-1098-2

A8436
To understand the Timer mode, it is noted that the secondary
winding charge current, I
where:
As shown in the three panels of figure 4, when the A8436 charges
a fully-discharged photoflash capacitor, I
slowly due to the low initial V
(Timer mode) sets a maximum timeframe of 18 μs for the off-
time as long as the SW node voltage is greater than 1.2 V. When
the off-time passes 18 μs, the internal MOSFET switch is turned
on, initiating the next charging cycle .
Input Current Limiting
The peak input current, I
configuring the ILIM pin:
I
L
N is the transformer turns ratio (N
Secondary
Primary
I
SWLIM
is the primary side inductance, and
is the secondary side current,
dI
1.0
1.2
1.4
(A)
Secondary
Setting
dt
=
SWLIM
Secondary
L
OUT
External ground
Float
Pull up to IC supply voltage
with a 1 to 10 kΩ resistor
, can be set to three levels by
Primary
, decreases linearly at a rate of:
V
. The A8436 internal timer
OUT
Connection
Secondary
ILIM Pin
N
Secondary
2
/ N
Primary
Photoflash Capacitor Charger with IGBT Driver
decreases very
).
(1)
Lower input current offers the advantage of a longer battery
lifetime. For faster charging time, however, use the highest
current limit.
I
waveform of I
lowered from 1.4 to 1.2 A, and charging slows slightly at the
lower current level.
Figure 5. Reducing I
SWLIM
I
IN(Avg)
V
OUT
may be adjusted during charging. Figure 5 shows a
SWLIM
I
SWLIM
SWLIM
= 1.4 A
being adjusted during charging. I
during charging
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
I
SWLIM
= 1.2 A
SWLIM
is
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