SP7612AEC6-L Exar Corporation, SP7612AEC6-L Datasheet - Page 6

• Manufacturer Part Number: SP7612AEC6-L
• Description: LED DRIVER LOW DROPOUT, SMD, 7612
• Manufacturer: Exar Corporation

Specifications of SP7612AEC6-L

• Primary Input Voltage: 5.5V
• No. Of Outputs: 2
• Voltage Regulator Case Style: SC-70
• No. Of Pins: 6
• Operating Temperature Range: -40°C To +85°C
• Operating Temperature Max: 85°C
• Operating Temperature: RoHS Compliant

SETTING THE LED CURRENT
The current flowing into LEDs is approximately 200
times greater than the current I
controlled by I
ing formula
I
For V
value can be evaluated using the diagram shown in the
Typical Performance Characteristics section. For any
other option, I
also be adjusted by driving ENABLE or the CTRL pin with
a PWM signal. The driving signal frequency should be
greater than 100Hz to avoid flickering, increasing to
more than 1MHz, if necessary.
LEDs are very sensitive to temperature. In most cases
the maximum allowed junction temperature is 100ºC.
The over temperature due to power dissipation is de-
scribed by the following:
T
where T
ambient temperature, Ø
thermal resistance, I is the LED current and V
forward voltage
When the temperature rises and the cathode voltage
increases, SP761X reduces the current through LEDs.
Refer to "LED Current vs. LED Cathode Voltage" graph
under the Typical Performance Characteristics section.
The SP761X driver's low dropout architecture can sig-
nificantly improve the efficiency compared to using simple
ballast resistors.
The system efficiency, defined as the ratio between the
LEDs power and the input supplied power can be
calculated as follows:
The lower the V
ciency. Efficiency can be further improved using a higher
V
Date: 10/11/04
LED
Efficiency = (V
j
IN
= T
with more LEDs as shown in example 3.
= 200 X (V
CONTROL
A
+ Ø
j
is the LED junction temperature, T
jA
:
x I xV
= 3V and a specified LED current, the R
CONTROL
SET
CONTROL
IN
.
CATHODE
- V
vs. V
F
CATHODE
and R
CTRL.
- V
jA
, the higher the system effi-
CTRL
is the junction to ambient
) / V
SET
The LED's brightness can
SP7611A/7612/7614 Low Dropout LED Driver for Any Color LED
) / R
SET
according to the follow-
IN
SET
. The LED current is
F
is the LED
A
is the
SET
6
APPLICATION NOTES
The ultra-low voltage drop across the SP761X series of
LED drivers, allows the devices to drive white, blue, and
other color LEDs in a wide range of input voltages. The
driver can be used in many applications. Any of the
SP761X series of LED drivers can be used in the
applications presented in this document, due to their
similar operation.
Example 1: Drive low V
from single cell Li-ion
When using white or blue low V
drivers low voltage drop, only 3.4V in V
the full 20mA LED current. At 3.1V, there is still 5mA
typical current available for the LEDs. The single cell Li-
ion is utilized in most applications like cell phones or
digital still cameras. In most cases, the Li-ion battery
voltage level only goes down to 3.0V, and not down to the
full discharge level (2.7V) before requesting the charger.
- T
- V
- V
- V
Key Advantages
1) No boost circuit needed for the LCD or keyboard
backlight
2) Drivers directly connected to a Li-ion battery
3) No EMI, no switching noise, no boost efficiency lost,
no capacitor, and no inductor
V CONTROL
DROP
F
IN
IN
(at 20mA) < 3.1V (Low V
(at 20mA) < - V
(at 5mA typical) ~ 3.1V
< 0.3V
V IN
APPLICATION INFORMATION
R SET
I SET
DROP
CTRL
LED4
F
+V
white or blue LEDs directly
© Copyright 2004 Sipex Corporation
F
F
= 3.4V
)
F
LEDs, and utilizing the
LED3
SP7611A
GND
IN
LED2
is needed for
®
®
LED1