STMicroelectronics STLD41PUR Schematic [ru]

White LED driver for mid-size LCD display backlight

Features

■ 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

STLD41

Datasheet − production data

DFN8 (3 x 3 mm)

signal connected to the EN pin. The LEDs can be
dimmed by applying a PWM signal to the PWM
pin.

Applications

■ 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 Package Packaging

STLD41PUR DFN8 (3 x 3 mm) 3000 parts per reel

June 2012 Doc ID 022283 Rev 5 1/19

This is information on a product in full production.

www.st.com

19

Contents STLD41

Contents

1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

6.1 PWM input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7 Selection of external components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7.1 CIN selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7.2 C

7.3 Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7.4 R

7.5 PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

OUT

value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

SENSE

8 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2/19 Doc ID 022283 Rev 5

STLD41 Block diagram

1 Block diagram

Figure 1. STLD41 block diagram

VIN

VLX

BIAS

20 V / 5 V
CONV

REFERENCE
PWM-V
CONV.

LOGIC

REF1

REF2

OVP

SOFT-START

PGND

STEP-UP
CONTROL

REF2

REF1

GND

FB

AM07829v1

Doc ID 022283 Rev 5 3/19

Pin configuration STLD41

2 Pin configuration

Figure 2. Pin connections (top view)

Table 2 .

Exposed pad PGND Power ground

Pin description

Pin n° Symbol Description

1 GND Ground

2 FB Feedback connection

3 GND Analog ground

4 PGND Power ground

5 VLX Inductor connection

6 EN Enable input

7 VIN Supply voltage

8 PWM_IN PWM input for the output current dimming

4/19 Doc ID 022283 Rev 5

STLD41 Maximum ratings

3 Maximum ratings

Table 3. Absolute maximum ratings

Symbol Parameter Value Unit

VIN Signal supply voltage - 0.3 to 23 V

VLX Inductor connection - 0.3 to 40 V

FB Feedback connection - 0.3 to 2 V

EN Logic pin - 0.3 to 21 V

PWM_IN PWM input - 0.3 to 6 V

ESD Human body model ± 2kV

P

TOT

T

OP

T

J

T

STG

1. Power dissipation is dependent on the PCB. PCB design recommendations are included in

Continuous power dissipation (at TA = 70 °C)

Operating ambient temperature range - 40 to 85 °C

Junction temperature - 40 to 150 °C

Storage temperature range - 65 to 150 °C

(1)

TBD mW

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.

Table 4. Thermal data

Symbol Parameter Value Unit

R

thJA

Thermal resistance junction-ambient 46 °C/W

Doc ID 022283 Rev 5 5/19

Typical application circuit STLD41

4 Typical application circuit

Figure 3. Application circuit schematic

Table 5. List of external components

Component Manufacturer Part number Value Size

C

IN

C

OUT

L

R

SENSE

Schottky diode STMicroelectronics STPS1L40M 1 A / 40 V 3.75 x 1 x 1.9 mm

LED OSRAM LWL283-Q1R2-3K8L-1-Z 20 mA / 3.1 V 0603

Murata GRM32ER71H106K 10 µF / 50 V 3.2 x 2.5 x 2.5 mm

Murata GRM31CR61H225KA88L 2.2 µF / 50 V 3.2 x 1.6 x 1.6 mm

Murata LQH6PPN470M43 47 µH / 1.25 A 6 x 6 x 4.3 mm

Coilcraft LPS6235-473MLB 47 µH / 1.2 A 6 x 6 x 3.5 mm

Tyco Electronics 1.3 Ω 0603 size

Note: The above listed components refer to a typical application with a maximum performance

setting. Operation of the STLD41 is not limited to the choice of these external components.

6/19 Doc ID 022283 Rev 5