SC604AIMLTR Semtech, SC604AIMLTR Datasheet - Page 11

• 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

Method 4. LED current may also be controlled by applying a PWM
signal to any of the CTRL2, CTRL1 and CTRL0 inputs. The circuit in
Figure 3 turns 4 LEDs on and off by applying a PWM signal to the
CTRL0 input. This circuit uses resistor R
current and the average LED current is then proportional to the
percentage of on-time when the CTRL0 pin is a logic low. Average
LED current is approximately equal to:
The recommended PWM frequency is between 100Hz and 500Hz.
Due to start up delay and ramp up time, frequency >500Hz will
result in error in the average value of I
naturally cause the LEDs to blink visibly.
In PWM applications where ILED4 is not used, keep ILED4 pin 13
open. Connecting ILED4 to ground can result in the charge pump
operating in open loop mode. Connecting ILED4 to V
but will cause shutdown current I
V
Table 4 - Summary of LED Current Control
Note: 1) “N” is the number of NMOS transistors used for brightness control.
POWER MANAGEMENT
Methods for Setting LED Current (Cont.)
IN
2005 Semtech Corp.
M
M
M
M
/ 100k.
e
e
e
e
h t
h t
h t
h t
E L
d o
d o
d o
d o
D
I
AVG
1
2
3
4
C
r u
= (t
e r
ON
N
t n
n A
M
P
I
LED_ON
W
C
O
l a
n o
S
M
g o
S
)/(t
r t
R
R
T C
w
R
S
s e
l o
T E
t i
ON
f e
L R
h c
s i
M
O
r e
+ t
Q
I x
o t
n
to increase to approximately
e
d e
n e
OFF
y l
s r
h t
p n
LED
e c
)
a P
d o
. Frequency <100Hz can
t u
V
l a r
SET
) s (
A
J D
l e l
to set the on state
i F
i F
i F
i F
IN
u g
C
u g
u g
u g
will work
c r i
e r
e r
e r
e r
t i u
1
2
3
f o
n o
n o
n o
n o
R
11
f e
a P
a P
a P
a p
r e
e g
e g
e g
e g
n e
1
1
0 1
0 1
e c
1
0
0
0
0
E L
5 .
5 .
5 .
5 .
Figure 3 - PWM Example Circuit
D
m
m
m
m
C
A
A
A
A
r u
< I
< I
< I
< I
e r
E L
E L
E L
E L
t n
D
D
D
D
<
<
<
<
R
3
3
3
3
n a
0
0
0
0
m
m
m
m
e g
A
A
A
A
F
C
x i
r u
r B
d e
2
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SC604A
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