ON Semiconductor NCS29001 User Manual

NCS29001

LED Backlight Driver

The NCS29001 is an integrated LED driver used in LCD display
backlighting applications. A configurable bill of materials allows the
designer to create a highly efficient solution for a variety of LCD
screen sizes. The NCS29001 uses a boost type converter to deliver
constant current in a string of LEDs. High accuracy PWM dimming is
supported for a frequency up to 500 Hz . The integrated soft start
function provides excellent control during the power up sequence to
avoid current overshoot. The device protects against output
overvoltage, open / short LED, and thermal overload. The NCS29001
is offered in the cost effective SOIC−14 package.

Features

• 8.5 V to 18 V Input Voltage Range

• ±1% Vref Voltage Accuracy to set LED Current

• PWM Controlled Dimming

• Soft Start Limits In−Rush Current

• Open Feedback Protection

• Open LED Protection

• Short LED Protection

• LED String Cathode Short to ground Protection

• Max Duty Cycle Above 90%

• SOIC−14 Package

• This is a Pb−Free Device

Typical Application

• TFT−LCD TV Panels

• LCD Monitor Panels

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SOIC−14 NB

CASE 751A

NCS29001= Specific Device Code
A = Assembly Location
WL = Wafer Lot
Y = Year
WW = Work Week
G = Pb−Free Package

14

NCS29001G

1

PIN CONNECTIONS

VIN

1

Vref

2

GND

3

PWMin

NCS29001

4

MARKING
DIAGRAM

AWLYWW

GATE

14

13

CS

PGND

12

11

PWMout

© Semiconductor Components Industries, LLC, 2013

October, 2013 − Rev. 1

FBP

STBY

RT

5

6

7

10

FBN

9

COMP

8

OVP

ORDERING INFORMATION

See detailed ordering and shipping information on page 15 of
this data sheet.

1 Publication Order Number:

NCS29001/D

NCS29001

Figure 1. Block Diagram

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NCS29001

PINOUT ASSIGNMENT

VIN

Vref

GND

PWMin

RT

FBP

STBY

1

2

3

4

5

6 9

7 8

NCS29001

GATE

14

13

CS

12

PGND

11

PMWout

10 FBN

COMP

OVP

Figure 2. NSC29001 Pinout

PIN DESCRIPTION

Pin # Symbol Type Description

1 VIN Input

2 VREF Output

3 GND Ground Analog ground.

4 PWMin Output PWM dimming control input.

5 RT Output The resistor connected between RT and GND sets the switching frequency

6 FBP Input The reference voltage for the feedback (FBN). Reference level can be adjusted from 0.5 V up to

7 STBY Input The converter enters in standby mode when STBY is floating or pulled high. When STBY goes

8 OVP Output This pin provides the overvoltage protection for the converter. When the voltage at this pin

9 COMP Power Loop compensation pin

10 FBN Input Feedback pin and LED cathode connection. External resistor from FBN to GND sets the LED

11 PWMout Output PWM dimming output driver.

12 PGND Ground Power ground.

13 CS Power This pin is used to sense the drain current of the external power MOSFET. It includes a built−in

14 GATE Output This pin is the output GATE driver for an external N−channel power MOSFET

VIN supply input. Small 1.0 mF low ESR bypass capacitor required from VIN to GND.

5 V / 10 mA reference voltage. Small 1.0 mF low ESR bypass capacitor required from VREF to
GND.

3.0 V using an external voltage divider.

from low to high the circuit will discharge the capacitors on the COMP pin and keep PWMout high
to discharge the output capacitor. STBY must remain high for 50 ms before the part enters
standby mode.

exceeds 1.2 V, the boost converter stops immediately and the device enters standby mode.

current.

blanking time.

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NCS29001

ATTRIBUTES

Characteristics Values

ESD protection (all pins)
Human Body Model (HBM) (Note 1)
Machine Model (MM)

Moisture sensitivity (Note 2) Level 1

Flammability Rating Oxygen Index: 28 to 34 UL 94 V−0 @ 0.125 in

Meets or exceeds JEDEC Spec EIA/JESD78 IC Latch−up Test

1. Human Body Model (HBM), R = 1500 W, C = 100 pF.

2. For additional information, see Application Note AND8003/D.

ABSOLUTE MAXIMUM RATINGS

Rating V

V

IN

PWMin −0.3 5.5 V

STBY −0.3 5.5 V

FBP −0.3 5.5 V

FBN −0.3 5.5 V

OVP −0.3 5.5 V

CS −0.3 5.5 V

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may
affect device reliability.

2 kV

150 V

MIN

V

MAX

−0.3 30 V

Unit

OPERATING CONDITIONS (T

V

IN

= +25°C)

A

Rating

Min Typ Max Unit

8.5 12 18 V

VIL_PWMin: PWMin input low voltage 1 V

VIH_PWMin: PWMin input high voltage 2 V

FBP 0.5 3.0 V

VIL_STBY: STBY input low voltage 1 V

VIH_STBY: STBY input high voltage 2 V

RT clock frequency resistor (Note 3) 20 140

Fdim dimming frequency (5 V amplitude) 100 300 Hz

Ddim dimming duty−cycle 3 95 %

NOTE: With respect to the GND pin.

3. Choose RT to keep clock frequency between 100 kHz and 500 kHz.

THERMAL RATINGS

Parameter Symbol Rating Unit

Junction to ambient thermal impedance (Note 4)

Maximum Junction Temperature (Note 5) T

Operating Ambient Temperature T

Storage temperature T

R

q

JA

J

A

stg

4. Power dissipation must be considered to ensure maximum junction temperature (qJA) is not exceeded.

5. Thermal Pad attached to PCB, 0 lfm airflow, and 76 mm x 76 mm copper area.

150 °C/W

+150 °C

−40 to +85 °C

−65 to +150 °C

kW

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NCS29001

ELECTRICAL SPECIFICATIONS V

Symbol

Parameter Condition Min Typ Max Unit

= 12 V, T

IN

= –40°C to 85°C; typical values are at 25°C

AMB

VIN (VIN Pin)

I

VIN

I

SHUTDOWN

Operating Supply Current VIN = 12 V; PWMin = 5 V; no load,

STBY = 5 V

Shutdown Mode Supply Current PWMin = GND

Ambient temperature 25°C

5 mA

12 uA

STBY = 5 V

UVLO Under Voltage Lockout

VIN Rising 7.5 8 8.5 V

Threshold

DUVLO

T

startup

UVLO Hysteresis 475 mV

Startup time Time from standby falling edge to

steady−state V

dimming pattern − (Note 6)

operation with 30%

boost

100 ms

VREF (VREF Pin)

VREF

Vref voltage

REF bypassed with a 1 mF capacitor to

4.95 5 5.05 V

GND

Line_Reg Line Regulation VIN = 8.5 V to 24 V at I_REF = 10 mA 0.08 0.20 %

Load_Reg Load Regulation 0 mA < I_REF < 10 mA at VIN = 12 V 0.6 mV/mA

ICC (Vref) Iref output current

VREF bypassed with a 1 mF capacitor

10 mA

to GND

GATE (GATE, RT Pins)

V

OH_GATE

I

SOURCE

I

SINK

T

RISE

T

FALL

R

OH

R

OL

D

LSS_MAX

F

OSC

±DF

V

RT

OSC

GATE output high voltage VIN = 12 V 7.5 10 15 V

GATE short circuit current 0.33 0.45 A

GATE sinking current 0.33 0.45 A

GATE output rise time Output voltage rise−time @ CL = 1 nF,

− 40 ns

10−90% of output signal (Note 6)

GATE output fall time Output voltage fall−time @ CL = 1 nF,

− 20 ns

90−10% of output signal (Note 6)

Source resistance 13

Sink resistance 6.0

Maximum Duty Cycle (Note 6) 93 95 %

Boost Switching Frequency

100 500 kHz

range

Frequency Accuracy −10 +10 %

RT pin output voltage 0.85 1 1.15 V

PWM DIMMING (PWMin, PWMout Pins)

V

OH_PWMout

DD_DIM

PWMout output high voltage VIN = 12 V 7.5 10 15 V

PWMout/PWMin Duty cycle

0.98 1 1.02 %

Tolerance

T

RISE

T

FALL

I

SOURCE

I

SINK

R

OH

R

OL

PWMout output rise time Output voltage rise−time @ CL = 1 nF,

− − 2 us

10−90% of output signal

PWMout output fall time Output voltage fall−time @ C

90−10% of output signal

= 1 nF,

L

− − 2 us

PWMout short circuit current 15 20 mA

PWMout sinking current 15 20 mA

Source resistance 270

Sink resistance 230

6. Guaranteed by characterization and design

W

W

W

W

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NCS29001

ELECTRICAL SPECIFICATIONS V

= 12 V, T

IN

Symbol UnitMaxTypMinConditionParameter

CURRENT SENSE (CS Pin)

V

CS

Reference voltage threshold for
current clamp monitoring OCP
comparator

I

RAMP

Slope compensation ramp 130 A/s

PROTECTION (OVP, FBP, FBN Pins)

V

V

V

UVPfb

T

DT

OVP

SCP

SD

SD

Output Overvoltage Protection
on OVP pin

Short Circuit Protection on OVP
pin

Output Undervoltage Protection
on FBN

Thermal Shutdown (Note 6) 140 150 160 °C

TSD hytheresis (Note 6) 15 °C

STANDBY (STBY Pin)

T

STANDBY

Standby mode delay (Note 6) 50 ms

6. Guaranteed by characterization and design

= –40°C to 85°C; typical values are at 25°C

AMB

APPLICATION DIAGRAM

0.5 0.6 V

1.2 1.3 V

60 75 mV

60 75 mV

V

Rref1

Rref2

IN

VIN

Inductor

R

Q1

RCS

Q1

D1

C

OUT

R

R

OVP1

OVP2

Q2

L

VIN

IC

NCS29001

1

VIN

2

Vref

3

4

PWMin

5

T

RT

6 FBP COMP

7 8STBY OVP

Backlight O

Standby

PWMout

GATE

PGNDGND

FBN

CS

14

R

sc

13

12

11

10

9

R

comp

C

comp

C

comp2

Figure 3. Application Schematic

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