SC604AIMLTR Semtech, SC604AIMLTR Datasheet - Page 4

• Manufacturer Part Number: SC604AIMLTR
• Description: IC,Laser Diode/LED Driver,LLCC,16PIN,PLASTIC
• Manufacturer: Semtech

Specifications of SC604AIMLTR

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

I
The LED current is determined by the R
vs. R
does not include the tolerance of the resistor R
maximum accuracy is required, a precision resistor is
needed. To calculate the error I
Current Matching
Current Matching refers to the difference in current from
one LED to the next. The I between any two LEDs will
meet this requirement. To calculate the error I
first identify the highest and lowest value of the 4 LED
currents, and use the formula:
1x Mode, 1.5x Mode and 2x Mode
1x Mode, 1.5x Mode and 2x Mode all refer to the charge
pump configuration. These modes boost the battery input
voltage and ensure there is enough voltage at V
that the regulated current will flow through the LEDs and
return via the I
POWER MANAGEMENT
Definitions
LED
I
2005 Semtech Corp.
LED-ERR
which reduces to ±
Accuracy
SET
I
or
data is found on pages 9 and 10). This term
[%] = ±
LED-LED-ERR
LED
[%] =
pins.
( )
I
LED
MEASURED
I
I
MAX
I
MAX
I
M AX
MAX
I LED
I
I
MAX
MIN
+ I
+ I
2
2
LED-ERR
+
MIN
MIN
I
I
MIN
MIN
-
[%], use the formula
I LED
- 1
- 1
100%
SET
100
100%
100%
resistor (I
%
LED-LED-ERR
SET
OUT
. If
LED
so
,
4
Input Current
The total input current of the SC604A is a function of
the sum of the LED currents, the charge pump mode
and the quiescent current. The quiescent current trend
is charted on page 12 and used to calculate I
following examples.
Example 1:
Answer 1:
Example 2:
Answer 2:
Mode Transition Voltage
Mode transition voltage refers to the input voltage at
the point just before the charge pump changes from a
weaker mode to a stronger mode. V
transition from 1x to 1.5x mode, and V
transition from 1.5x to 2x mode. Equations for V
and V
I
62.4mA
I
Mode = 1x, I
I
Mode = 1.5x, I
I
92.4mA
IN
IN
LED1
LED1
TRANS1.5X
= I
= I
I
(I
IN
+I
+I
LED1
= I
OUT
OUT
LED2
LED2
+I
OUT
+I
+I
LED2
are given on page 7.
Mode + I
Mode + I
LED3
LED3
Mode + I
+I
Q
+I
+I
LED3
= 2.4mA,
Q
LED4
LED4
= 2.4mA,
+I
LED4
Q
= 4 15mA = 60mA
Q
= 4
Q
= 60mA
= 60mA
=
) Mode + I
15mA = 60mA
1 + 2.4mA =
1.5 + 2.4mA =
Q
www.semtech.com
SC604A
TRANS1.5X
TRANS1X
IN
is the
in the
is the
TRANS1X