LP3936SLX/NOPB National Semiconductor, LP3936SLX/NOPB Datasheet - Page 19

• Manufacturer Part Number: LP3936SLX/NOPB
• Description: IC LED DRVR WT/RGB BCKLGT 32TCSP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Backlight, White LED, RGB (I²C Interface)r

Specifications of LP3936SLX/NOPB

• Constant Current: Yes
• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 9
• Internal Driver: Yes
• Type - Primary: Backlight, Flash/Torch, LED Blinker, Light Management Unit (LMU)
• Type - Secondary: RGB, White LED
• Frequency: 1MHz
• Voltage - Supply: 3 V ~ 6 V
• Voltage - Output: 5.3V
• Mounting Type: Surface Mount
• Package / Case: 32-Laminate TCSP
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 120mA
• Internal Switch(s): Yes
• Efficiency: 90%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LP3936SLX

WLED Current Adjustment
Recommended External
Components
OUTPUT CAPACITOR, C
The output capacitor C
the output ripple voltage. In general, the higher the value of
C
ramic capacitors with low ESR are the best choice. At the
Symbol
C
C
C
C
C
C
RT
RDO
C
L
D
BOOST
OUT
VDD1
VDD2
OUT
IN
VDDIO
VDDA
VREF
OUT
, the lower the output ripple magnitude. Multilayer ce-
WLED[7:0]
0000 0000
0000 0001
0000 0010
0000 0011
1111 1101
1111 1110
1111 1111
Temperatures −40˚C, +25˚C, +85˚C
•
•
WLED Output Current vs Voltage
V
V
Output capacitor from FB to GND
Input capacitor from Battery Voltage to GND
V
Internal LDO output capacitor, between V
Oscillator Frequency Bias Resistor
DO output pull-up resistor
Reference Voltage Capacitor, between V
Boost converter inductor
Rectifying Diode, V
DD1
DD2
DDIO
bypass capacitor
bypass capacitor
bypass capacitor
OUT
OUT
directly affects the magnitude of
WLED Current
Symbol Explanation
(Typical)
F
25.3
25.4
25.5
0.1
0.2
0.3
@
0
•
•
Maxload
List of Recommended External Components
20081431
Units
mA
mA
mA
mA
mA
mA
mA
•
•
REF
DDA
and GND
and GND
19
lighter loads, the low ESR ceramics offer a much lower V
ripple than the higher ESR tantalums of the same value. At
the higher loads, the ceramics offer a slightly lower V
ripple magnitude than the tantalums of the same value.
However, the dv/dt of the V
much lower than the tantalums under all load conditions.
Capacitor voltage rating must be sufficient, 10V is recom-
mended. It should be noted that with some capacitor types
the actual capacitance depends heavily on the capacitor DC
voltage bias.
INPUT CAPACITOR, C
The input capacitor C
input ripple voltage and to a lesser degree the V
higher value C
age rating must be sufficient, 10V is recommended.
OUTPUT DIODE, D
A Schottky diode should be used for the output diode. To
maintain high efficiency the average current rating of the
schottky diode should be larger than the peak inductor cur-
rent (1A). Schottky diodes with a low forward drop and fast
switching speeds are ideal for increasing efficiency in por-
table applications. Choose a reverse breakdown of the
schottky diode larger than the output voltage. Do not use
ordinary rectifier diodes, since slow switching speeds and
long recovery times cause the efficiency and the load regu-
lation to suffer.
INDUCTOR, L
The high switching frequency enables the use of the small
surface mount inductor. A 10 µH shielded inductor is sug-
gested. Values below 4.7 µH should not be used. The induc-
tor should have a saturation current rating higher than the
peak current it will experience during circuit operation (
Less than 300 mΩ ESR is suggested for high efficiency.
Open core inductors cause flux linkage with circuit compo-
nents and interfere with the normal operation of the circuit.
This should be avoided. For high efficiency, choose an in-
ductor with a high frequency core material such as ferrite to
reduce the core losses. To minimize radiated noise, use a
toroid, pot core or shielded core inductor. The inductor
should be connected to the OUT pin as close to the IC as
possible. Examples of suitable inductors are TDK types
LLF4017T-100MR90C and VLF4012AT-100MR79 and Coil-
craft type DO3314T-103 (unshielded).
Value
100
100
0.3
10
10
82
10
1
1
1
1
IN
will give a lower V
Unit
kΩ
kΩ
µH
OUT
µF
µF
µF
µF
µF
µF
nF
V
IN
IN
directly affects the magnitude of the
OUT
Ceramic, X7R
Ceramic, X7R
Ceramic, X7R/Y5V
Ceramic, X7R/Y5V
Ceramic, X7R
Ceramic, X7R
1% (Note 16)
Ceramic, X7R
Shielded, Low ESR, I
Schottky Diode
ripple with the ceramics is
IN
ripple. Capacitor volt-
Type
OUT
www.national.com
SAT
ripple. A
A
A
1A).
OUT
OUT
1A