SC5014A 查看數據表（PDF） - Semtech Corporation

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SC5014A

High Efficiency 2-Channel HB LED Driver with I2C Interface and Direct PWM Dimming

Semtech Corporation 

SC5014A

Applications Information (continued)

Fault Protection

The SC5014A provides fault detection for low supply

voltage, LED related faults, boost converter over-voltage

and thermal shutdown. The open drain output pin (FLT)

indicates a system fault. The nature of the fault can be read

from the fault status resistor (register address: 0x00) via I2C

interface. Refer to Table 1 for a description of the Fault

Protection Modes.

Other Possible Configurations

Depending on different application requirements, the

SC5014A can also be easily configured to other topolo-

gies, such as the SEPIC configuration shown in Figure 4,

page 21.

Li-Ion Powered Display Configuration

If a Li-Ion powered display application is required, VCC is

needed to power with 5V. However, VIN can be set lower

from 3V to 4.2V for example. An advantage of this type of

configuration is that it provides higher efficiency. Please

use Figure 3 on page 20 for reference.

High Output Voltage Configuration

If a high output voltage application is required, an addi-

tional external cascode MOSFET can be added on each IO

pin to meet such requirement, please refer to Figure 5 on

page 21 for reference.

In this case, the upper limit on the output voltage is mainly

determined by the rating of the external MOSFET, heat

dissipation, etc.

PCB Layout Considerations

The placements of the power components outside the

SC5014A should follow the layout guidelines of a general

boost converter. The Detailed Application Circuit is used

as an example.

. Capacitor (C2) should be placed as close as possible to

the VCC and AGND to achieve the best performance.

2. Capacitor (C1) is the input power filtering capacitor for

the boost. It needs to be tied to PGND.

3. The converter power train inductor (L1) is the boost

converter input inductor. Use wide and short traces

connecting these components.

4. The output rectifying diode (D1) uses a Schottky diode

for fast reverse recovery. Transistor (Q1) is the external

switch. Resistor (R9) is the switch current sensing resis-

tor. To minimize switching noise for the boost con-

verter, the output capacitor (C6) should be placed

such that the loop formed by Q1, D1, C6 and R9, is

minimized. The output of the boost converter is used

to power up the LEDs. Use wide and short trace con-

necting Pin NDRV and the gate of Q1. The GNDs for R9

and C6 should be PGND. These components should

be close to the SC5014A.

5. Resistor (R8) is the output current adjusting resistor

for IO1 through IO2 and should return to AGND. Place

it next to the IC.

6. Resistor (R6) is the switching frequency adjusting

resistor and should return to AGND. Place it next to

the IC.

7. The decoupling capacitor (C3) for Pin REF should

return to AGND. Place it next to the IC.

8. Resistors (R4, R5) form a divider to set the SCP level, R4

should return to AGND. Place it next to the IC.

9. Resistors (R2, R1) form a divider to set the UVLO level

for UVLO pin. R1 should return to AGND. Place it next

to the IC.

0. R11 and R10 form a divider to set the OVP level for

VOUT, R10 should return to AGND. Place it next to the

IC.

. All the traces for components with AGND connection

should avoid being routed close to the noisy areas.

2. An exposed pad is located at the bottom of the

SC5014A for heat dissipation and analog ground. A

copper area underneath the pad is used for better

heat dissipation. On the bottom layer of the PCB

another copper area, connected through vias to the

top layer, is used for better thermal performance. The

pad at the bottom of the SC5014A should be con-

nected to AGND. AGND should be connected to PGND

at a single point for better noise immunity.

16

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