ssl3250a NXP Semiconductors, ssl3250a Datasheet - Page 17

• Manufacturer Part Number: ssl3250a
• Description: Photo ?ash Dual Led Driver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Table 6.
Legend: * default register value
9. Application design-in information
SSL3250A_2
Product data sheet
Address
01h
02h
03h
Register
Timer control
Flash strobe
Status
Description of registers
9.1 Input capacitor
9.2 Output capacitor
For good input voltage decoupling a low ESR ceramic capacitor is highly recommended. A
4.7 F (X5R/X7R) 6.3 V is the minimum recommended value. Since the input capacitor is
supplying the input ripple current, a larger capacitor will improve transient behavior of the
regulator and EMI behavior of the power supply. Taking the capacitor DC bias and the
temperature derating specifications into account, a 10 F (X5R/X7R) is preferred.
Although it is increasing the component count, a smaller capacitor of 100 nF (X5R/X7R)
placed in parallel to the input capacitor will also improve EMI behavior.
When the circuit is used in other than battery powered applications and the input capacitor
is located relatively far from the DC buffer capacitors, it is recommended to add a 150 F
tantalum or a 470 F electrolytic capacitor in parallel near the input capacitor.
The output capacitor supplies the current to the main LED, while the inductor is being
charged, and it also ensures loop stability. The minimum capacitance for stable loop
operation would be 2.2 F, but taking the capacitor DC bias and the temperature derating
specifications into account, a low ESR ceramic capacitor of 4.7 F (X5R/X7R) is highly
recommended. A higher value of capacitance will improve output current ripple, while
Bit
7 to 5
4
3 to 0
7 to 1
0
7 to 4
3
2
1
0
…continued
Symbol
Reserved
TO_DEF
TO
Reserved
FLASH_STRB R/W
Reserved
OStrig
OTPtrig
TOtrig
OVPtrig
Rev. 02 — 21 April 2009
Access
-
R/W
R/W
-
-
R
R
R
R
Value
-
0
1
0000
0001
.....
1110
1111
-
0
1
-
0
1
0*
1
0
1
0
1
*
*
*
*
*
*
Description
Select time-out limit (default)
Select timed operation
820 ms (default)
765 ms
.....
56 ms
1 ms
-
-
Enable flash
LED not shorted to GND
LED shorted to GND
Temperature < maximum temperature
Temperature > maximum temperature;
Protection triggered
Flash time < Time-out
Flash time > Time-out, Protection triggered
V
V
O
O
< V
> V
ovp
ovp
, protection triggered
Photo flash dual LED driver
SSL3250A
© NXP B.V. 2009. All rights reserved.
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