STLD41
White LED driver for mid-size LCD display backlight
Datasheet
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production data
Features
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Boost DC-DC converter
Drives up to 40 LEDs (4 strings of 10) with a
total current up to 120 mA
Input voltage range: 3.0 V to 21 V
Output current control
1.4 MHz fixed frequency PWM control
PWM input for output current dimming with
frequency range 25 kHz - 50 kHz
2 A integrated switch
Overvoltage protection
Chip overtemperature detection and protection
Less than 1 µA standby current
Soft-start function
Package DFN8 (3 x 3) 0.65 mm pitch
signal connected to the EN pin. The LEDs can be
dimmed by applying a PWM signal to the PWM
pin.
DFN8 (3 x 3 mm)
Applications
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Mini PCs
PMP & PND
Printers
Game consoles
Description
The STLD41 is a boost converter that operates
from 3.0 V to 21 V and can provide an output
voltage as high as 38 V. It can drive up to 40 white
LEDs connected in 4 strings of 10 LEDs in series.
The total output current capability is 120 mA at an
output voltage of 38 V. Regulation is performed by
the internal error amplifier which works with the
feedback voltage from the sensing resistor. The
device can be turned ON/OFF by way of the logic
Table 1.
Device summary
Order code
STLD41PUR
Package
DFN8 (3 x 3 mm)
Packaging
3000 parts per reel
June 2012
This is information on a product in full production.
Doc ID 022283 Rev 5
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www.st.com
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Contents
STLD41
Contents
1
2
3
4
5
6
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1
PWM input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7
Selection of external components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1
7.2
7.3
7.4
7.5
C
IN
selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
C
OUT
selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
R
SENSE
value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8
9
10
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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Doc ID 022283 Rev 5
STLD41
Block diagram
1
Block diagram
Figure 1.
STLD41 block diagram
VIN
VLX
BIAS
LOGIC
OVP
REF2
20 V / 5 V
CONV
STEP-UP
CONTROL
REF1
REFERENCE
PWM-V
CONV.
REF2
SOFT-START
REF1
FB
PGND
GND
AM07829v1
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Pin configuration
STLD41
2
Pin configuration
Figure 2.
Pin connections (top view)
Table 2.
Pin description
Symbol
GND
FB
GND
PGND
VLX
EN
VIN
PWM_IN
PGND
Ground
Feedback connection
Analog ground
Power ground
Inductor connection
Enable input
Supply voltage
PWM input for the output current dimming
Power ground
Description
Pin n°
1
2
3
4
5
6
7
8
Exposed pad
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Doc ID 022283 Rev 5
STLD41
Maximum ratings
3
Table 3.
Maximum ratings
Absolute maximum ratings
Parameter
Signal supply voltage
Inductor connection
Feedback connection
Logic pin
PWM input
Human body model
Continuous power dissipation (at T
A
= 70 °C)
(1)
Operating ambient temperature range
Junction temperature
Storage temperature range
Value
- 0.3 to 23
- 0.3 to 40
- 0.3 to 2
- 0.3 to 21
- 0.3 to 6
±
2
TBD
- 40 to 85
- 40 to 150
- 65 to 150
Unit
V
V
V
V
V
kV
mW
°C
°C
°C
Symbol
VIN
VLX
FB
EN
PWM_IN
ESD
P
TOT
T
OP
T
J
T
STG
1. Power dissipation is dependent on the PCB. PCB design recommendations are included in
Section 7.5: PCB layout.
Note:
Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Thermal data
Parameter
Thermal resistance junction-ambient
Value
46
Unit
°C/W
Table 4.
Symbol
R
thJA
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