A8439EEJTR-T Allegro Microsystems Inc, A8439EEJTR-T Datasheet - Page 10

• Manufacturer Part Number: A8439EEJTR-T
• Description: IC CHARGER PHOTO FLASH 10MLP
• Manufacturer: Allegro Microsystems Inc

Specifications of A8439EEJTR-T

• Applications: Photoflash Capacitor Charger
• Current - Supply: 1.5mA
• 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: 620-1203-2; A8439EEJTR-T

A8439
decoder circuit to receive ILIM inputs and set I
minimum duration of 54 μs.
Figure 5 shows the timing definition of the primary current
limiting circuit. At the end of the setup period, t
current starts to ramp up to the set I
remains in effect as long as the CHARGE pin is high. To reset the
ILIM counter, pull the CHARGE pin low before clocking in the
new setting.
After the first start-up or an ILIM counter reset, each new current
limit can be set by sending a burst of pulses to the CHARGE pin.
The first rising edge starts the ILIM counter, and up to 8 rising
edges will be counted to set the I
width, t
(up to 7 more) can be as short as 0.2 μs. The last low-to-high
edge must arrive within 54 μs from the first edge. The CHARGE
pin will stay high afterwards. The four panels of figure 6 show
examples of the pulse streams and the resulting current levels.
Figure 4. ILIM Clock Timing Definition
Figure 5. Current Limit Programming Example (I
CHARGE
I
SW
Clock input at
CHARGE pin
ILIM1(H)
0 μs
Four rising edges
within t
20 μs
, must be at least 20 μs long. Subsequent pulses
0 μs
Start ILIM counter
t
first pulse width
ILIM(SU)
t
ILIM1(H)
First rising
ILIM(L)
edge
t
ILIM(SU)
≥ 0.2 μs
= min.
ILIM setup time
54 μs
20 μs
= maximum
Photoflash Capacitor Charger with IGBT Driver and Refresh
Switching
SWLIM
starts
Subsequent rising
edges (0 to 7)
SWIM
t
Reset ILIM counter
ILIM(H)
level. The first pulse
. The I
I
SWLIM4
SWLIM4
≥ 0.2 μs
= 0.86 A
SWLIM
SWLIM
ILIM(SU)
54 μs
selected).
Switching
, and has a
setting
starts
, primary
Switching
stops
Figure 6. ILIM programming waveforms for I
and 0.86 A.
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
(D) 0.86 A
(A) 1.4 A
(B) 1.2 A
(C) 1.0 A
SWLIM
= 1.4 A, 1.2 A, 1.0 A,
10