MP24183DQ [MPS]

1A, 55V, Programmable Frequency White LED Driver;


型号：	MP24183DQ
厂家：	MONOLITHIC POWER SYSTEMS
描述：	1A, 55V, Programmable Frequency White LED Driver
文件：	总12页 (文件大小：442K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MP24183

1A, 55V, Programmable Frequency

White LED Driver

The Future of Analog IC Technology

FEATURES

DESCRIPTION



1A Maximum Output Current

Unique Step-up/down Operation (Buck-

Boost Mode)

The MP24183 is a 55V, 1A, white LED driver

suitable for either step-down or inverting

step-up/down applications. It achieves 1A peak

output current over a wide input supply range

with excellent load and line regulation. Current

mode operation provides fast transient

response and eases loop stabilization. Fault

condition protection includes thermal shutdown,

cycle-by-cycle peak current limiting, input over

voltage protection, open strings protection and

output short circuit protection.

The MP24183 incorporates both DC and PWM

dimming onto a single control pin. The separate

input reference ground pin allows for direct

enable and/or dimming control for a positive to

negative power conversion.



Wide 4.5V to 55V Operating Input Range for

Step-Down Applications (Buck Mode)

0.28Ω Internal Power MOSFET Switch

Adjustable Switching Frequency

Analog and PWM Dimming

0.198V Reference Voltage

5μA Shutdown Mode

No minimum LED required

Stable with Low ESR Output Ceramic

Capacitors



Cycle-by-Cycle Over Current Protection

Thermal Shutdown Protection

Open Strings Protection

Input Over Voltage Protection

Output Short Circuit Protection

Available in 10-Pin 3x3 QFN Package

The MP24183 requires a minimum number of

readily available standard external components

and is available in a 10-pin 3mm x 3mm QFN

package.

APPLICATIONS



General LED Illuminations

LCD Backlight Panels

Handheld Computers

Automotive Internal Lighting

Portable Multimedia Players

Portable GPS Devices

“MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic

Power Systems, Inc.

TYPICAL APPLICATION

VIN

VDD OVP

BST

4.7

100nF

4.5V<VIN<55V

MP24183

2.2

B360A

EN/DIM

INGND

OFF

DC or PWM Input

VSS COMP RSET

1nF

MP24183 Rev. 1.0

8/28/2008

www.MonolithicPower.com

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

ORDERING INFORMATION

Part Number*

Package

Top Marking

Free Air Temperature (T_A)

MP24183DQ

3x3 QFN10

-40C to +85C

* For Tape & Reel, add suffix –Z (e.g. MP24183DQ–Z).

For RoHS compliant packaging, add suffix –LF (e.g. MP24183DQ–LF–Z)

PACKAGE REFERENCE

TOP VIEW

VDD

VSS

10 SW

BST

OVP

INGND

EN/DIM

RSET

COMP

ABSOLUTE MAXIMUM RATINGS ⁽¹⁾

Supply Voltage V_DD– V_SS............................. 60V

Thermal Resistance ⁽⁴⁾

3x3 QFN10..............................50 ...... 12...C/W

θ_JA

θ_JC

_SW– V_SS..............................-0.3V to V_IN+ 0.3V

_BST...................................................... V_SW+ 6V

_OVP– V_SS.......................................-0.3V to +6V

_EN– V_INGND.....................................-0.3V to +6V

_DIM– V_INGND....................................-0.3V to +6V

Notes:

1) Exceeding these ratings may damage the device.

2) The maximum allowable power dissipation is a function of the

maximum junction temperature T_J(MAX), the junction-to-

ambient thermal resistance θ_JA, and the ambient temperature

T_A. The maximum allowable continuous power dissipation at

any ambient temperature is calculated by P_D(MAX) = (T_J

(MAX)-T_A)/θ_JA. Exceeding the maximum allowable power

dissipation will cause excessive die temperature, and the

regulator will go into thermal shutdown. Internal thermal

shutdown circuitry protects the device from permanent

damage.

_INGND– V_SS.....................................-0.3V to 60V

(2)

Continuous Power Dissipation (T_A= +25°C)

………………………………………………....2.5W

Junction Temperature...............................150C

Lead Temperature ....................................260C

Storage Temperature............... -65C to +150C

3) The device function is not guaranteed outside of the

recommended operating conditions.

4) Measured on JESD51-7, 4-layer PCB.

Recommended Operating Conditions ⁽³⁾

Supply Voltage V_DD– V_SS.................4.5V to 55V

Operating Junct. Temp (T_J)..... -40C to +125C

MP24183 Rev. 1.0

8/28/2008

www.MonolithicPower.com

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

ELECTRICAL CHARACTERISTICES

V_IN= 12V, T_A= +25C, all voltages with respect to V_SS, unless otherwise noted.

Parameters

Symbol Condition

Min

Typ

Max

Units

Feedback Voltage

Feedback Current

Switch-On Resistance ⁽⁵⁾

Switch Leakage

Current Limit ⁽⁵⁾

V_FB

I_FB

0.188 0.198 0.208

4.5V  V_IN 55V

V_FB= 0.22V

-50

mΩ

μA

R_DS(ON)

280

V_EN= 0V, V_SW= 0V

2.0

0.5

_FB= 0.19V,

Rset=100kΩ

_FB= 0.19V, Rset

Oscillator Frequency

f_SW

MHz

Default oscillator frequency

f_{SW_default}

1.05

1.35

1.65

3.6

open

Fold-back Frequency

V_FB= 0V, V_OVP=0V

V_FB= 0.19V

250

100

3.3

100

2.1

kHz

μA

Maximum Duty Cycle

Minimum On-Time ⁽⁵⁾

t_ON

Under Voltage Lockout Threshold Rising

Under Voltage Lockout Threshold Hysteresis

EN Input Current

EN OFF Threshold (w/Respect to INGND)

EN ON Threshold (w/Respect to INGND)

Minimum EN Dimming Threshold

Maximum EN Dimming Threshold

Supply Current (Quiescent)

V_EN= 2V

V_ENFalling

V_ENRising

V_FB= 0V

0.4

0.6

0.8

1.5

1.0

0.6

1.25

0.7

1.4

0.8

3.4

150

1.2

V_FB= 0.2V

V_EN= 2V, V_FB= 1V

V_EN=0V

I_Q

I_off

μA

°C

Supply Current (Quiescent) at EN Off

Thermal Shutdown ⁽⁵⁾

Open LED OV Threshold

V_OVP

1.1

1.3

Open LED OV Hysteresis

V_OVP

hys

Notes:

5) Guaranteed by design.

MP24183 Rev. 1.0

8/28/2008

www.MonolithicPower.com

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

PIN FUNCTIONS

Pin #

Name Description

Supply Voltage. The MP24183 operates from a +4.5V to +55V unregulated input (with

respect to VSS). C1 is needed to prevent large voltage spikes from appearing at the input.

VDD

Power Return Pin. Connect to the lowest potential in the circuit, which is typically the anode

of the Schottky rectifier. This pin is the voltage reference for the regulated output voltage.

For this reason care must be taken in its layout. This node should be placed outside of the

D1 to C1 ground path to prevent switching current spikes from inducing voltage noise into

the part. The exposed pad is also connected to this pin.

VSS

Over Voltage Protection Pin. Use a voltage divider to program OVP threshold. When the

OVP pin voltage reaches the shutdown threshold 1.2V, the switch will be turned off and will

recover when OVP voltage decreases sufficiently. When the OVP pin voltage (with respect

to VSS) is lower than 0.4V and FB pin voltage is lower than 0.1V, the chip reecognizes this

as short circuit condition and the operating frequency will be folded back. Program the OVP

pin voltage from 0.4V to 1.2V for normal operation.

OVP

LED Current Feedback Input. MP24183 regulates the voltage across the current sensing

resistor between FB and VSS. Connect the current sensing resistor from the bottom of the

LED strings to VSS. The FB pin is connected to the bottom of the LED strings. The

regulation voltage is 0.198V.

Output of error amplifier. Connect a 1nF or larger capacitor on COMP to improve the

stability and to provide a soft on at start up and PWM dimming.

COMP

Frequency Set Pin. Connect a resistor to VSS to set the switching frequency and an 1nF

RSET capacitor to VSS to bypass the noise. Leaving this pin open gets a default operating

frequency 1.35MHz.

On/Off Control Input and Dimming Command Input. A voltage greater than 0.6V will turn on

the chip. Both DC and PWM dimming are implemented on this pin. When the EN/DIM pin

EN/DIM voltage (with respect to INGND) rises from 0.7V to 1.4V, the LED current will change from

0% to 100% of the maximum LED current. To use PWM dimming, apply a 100Hz to 2kHz

square wave signal with amplitude greater than 1.4V to this pin.

INGND Input Ground Reference. This pin is the reference for the EN/DIM signal.

Bootstrap. A capacitor is connected between SW and BST pin to form a floating supply

BST

across the power switch driver. A 100nF or larger ceramic capacitor is recommended to

provide sufficient energy to drive the power switch’s gate above the supply voltage.

Switch Output. SW is the source of the internal MOSFET switch. Connect this pin to the

power inductor and the cathode of the Schottky rectifier.

Exposed pad should be connected to VSS in step up/down mode.

MP24183 Rev. 1.0

8/28/2008

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MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

TYPICAL PERFORMANCE CHARACTERISTICS

VIN=20V, ILED=0.7A, two 3W LED in series, step down application, unless otherwise noted.

WLED current

vs Dimming Duty

WLED Current vs VEN

Efficiency

100

800

700

600

500

400

300

200

100

2WLED, 710mA

3WLED, 710mA

1WLED, 710mA

700

600

500

400

300

200

100

-100

0.2 0.4 0.6 0.8

DIMMING DUTY

1.2

10 20

30 40

50 60

400

800

1200 1600

INPUT VOLTAGE(V)

VEN(mV)

MP24183 Rev. 1.0

8/28/2008

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MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

VIN=20V, ILED=0.7A, two 3W LED in series, step down application, unless otherwise noted.

PWM Dimming

EN on

Steady State

PWM

5V/div.

10V/div.

INDUCTOR

500mA/div.

INDUCTOR

500mA/div.

WLED

500mA/div.

500A/div.

400ns/div.

2ms/div.

40us/div.

VDD-VSS OVP Protection

Open LED Protection

EN off

5V/div.

50V/div.

10V/div.

OVP

1V/div.

20V/div.

LED+

INDUCTOR

5V/div.

500mA/div.

OUT

5V/div.

INDUCTOR

WLED

INDUCTOR

500mA/div.

1A/div.

4us/div.

20ms/div.

2us/div.

MP24183 Rev. 1.0

8/28/2008

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MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

FUNCTIONAL BLOCK DIAGRAM

Figure 1—Functional Block Diagram

MP24183 Rev. 1.0

8/28/2008

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MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

OPERATION

The MP24183 is a current mode regulator. The

EA output voltage is proportional to the peak

inductor current.

Dimming Control

The MP24183 allows both DC and PWM

dimming. When the voltage on EN is less than

0.6V, the chip is turned off. For analog

dimming, when the voltage on EN is from 0.7V

to 1.4V, the LED current will change from 0% to

100% of the maximum LED current. If the

voltage on EN pin is higher than 1.4V,

maximum LED current will be generated. For

PWM dimming, its amplitude (VDIM – VINGND)

must exceed 1.4V. The PWM frequency is

recommended in range of 100Hz to 2kHz to get

a good dimming linearity.

At the beginning of a cycle, M1 is off. The EA

output voltage is higher than the current sense

amplifier output, and the current comparator’s

output is low. The rising edge of the 1.35MHz

CLK signal sets the RS Flip-Flop. Its output

turns on M1 thus connecting the SW pin and

inductor to the input supply.

The increasing inductor current is sensed and

amplified by the Current Sense Amplifier. Ramp

compensation is summed to the Current Sense

Amplifier output and compared to the Error

Amplifier output by the PWM Comparator.

When the sum of the Current Sense Amplifier

output and the Slope Compensation signal

exceeds the EA output voltage, the RS Flip-

Flop is reset and M1 is turned off. The external

Schottky rectifier diode (D1) conducts the

inductor current.

Output Short Circuit Protection

The MP24183 integrates output short circuit

protection. When the output is shorted to VSS,

the voltage on OVP pin which detects the

output voltage gets smaller than 0.4V, and FB

pin senses no voltage (<0.1V) as no current

goes through the WLED. At this condition, the

operating frequency is folded back to decrease

the power consumption.

If the sum of the Current Sense Amplifier output

and the Slope Compensation signal does not

exceed the EA output for a whole cycle, then

the falling edge of the CLK resets the Flip-Flop.

In Buck-boost application, when there is

possibility that the LED+ short circuit to VSS, it

is recommended to add a diode from VSS to

INGND to protect the IC, as shown in below

Figure 2 .

The output of the Error Amplifier integrates the

voltage difference between the feedback and

the 0.198V reference. The polarity is a FB pin

voltage lower than 0.198V increases the EA

output voltage. Since the EA output voltage is

proportional to the peak inductor current, an

increase in its voltage also increases the

current delivered to the output.

Open LED Protection

If the LED is open, there is no voltage on the

FB pin. The duty cycle will increase until

V(VDD)-V(VSS) reaches 55V or OVP-VSS

reaches the shutdown threshold set by the

external resistor divider. The top switch will turn

off till the voltage V(VDD)-V(VSS) and OVP-

VSS decreases sufficiently.

Figure 2—Buck-boost Application When

LED+ Possibly Short to VSS

MP24183 Rev. 1.0

8/28/2008

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MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

Where ΔI_Lis the inductor ripple current.

APPLICATION INFORMATION

Choose the inductor ripple current to be 30% of

the maximum load current. The maximum

inductor peak current is calculated from:

Setting the LED Current

The external resistor is used to set the

maximum LED current (see the schematic on

front page) through the use of the equation:

0. 198 V

I_L

I_L(MAX) I_LOAD



SENSE



LED

Under light load conditions below 100mA, a

larger inductance is recommended for improved

efficiency.

Setting the Operating Frequency

The resistor on Rset pin is used to set the

operating frequency. A 1nF capacitor is

recommended to bypass this pin to GND.

The relationship between the operating

frequency and the Rest resistor is as the

following curve. A 20kΩ to 200kΩ Rset resistor

is recommended, which sets the operating

frequency from around 1.3MHz to 250kHz.

Leaving the RSET pin open will set the

operating frequency to the default operating

Also note that the maximum recommended load

current is 2A if the duty cycle exceeds 35%.

Selecting the Input Capacitor

The input capacitor reduces the surge current

drawn from the input supply and the switching

noise from the device. The input capacitor

impedance at the switching frequency should

be less than the input source impedance to

prevent high frequency switching current from

passing through the input. Ceramic capacitors

with X5R or X7R dielectrics are highly

recommended because of their low ESR and

small temperature coefficients. For most

applications, a 4.7μF capacitor is sufficient.

frequency 1.35MHz.

Frequency vs. RSET

1400

1200

1000

800

Selecting the Output Capacitor

The output capacitor keeps the output voltage

ripple small and ensures feedback loop stable.

The output capacitor impedance should be low

at the switching frequency. Ceramic capacitors

with X5R or X7R dielectrics are recommended

for their low ESR characteristics. For most

applications, a 2.2μF ceramic capacitor will be

sufficient.

Series1

600

400

200

100 150 200 250

Selecting the Inductor

(Step-Down Applications, see Figure 3)

A 1μH to 47μH inductor with a DC current rating

of at least 25% percent higher than the

maximum load current is recommended for

most applications. For high efficiency, the

inductor’s DC resistance should be less than

200mꢀ. Refer to Table 2 for suggested surface

mount inductors. For most designs, the required

inductance value can be derived from the

following equation.

PC Board Layout

The high current paths (VSS, VDD and SW)

should be placed very close to the device with

short, direct and wide traces. The input

capacitor needs to be as close as possible to

the VDD and VSS pins. The external feedback

resistors should be placed next to the FB pin.

Keep the switch node traces short and away

from the feedback network.

V_OUT (V_IN V_OUT

V_IN I_L f_SW

)

L 

MP24183 Rev. 1.0

8/28/2008

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MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

Table 2—Suggested Surface Mount Inductors

Dimensions

Current

Rating (A)

Manufacturer

Part Number

Inductance(μH) Max DCR(Ω)

L x W x H (mm³)

Toko

Sumida

Wurth Electronics

A921CY-4R7M

CDRH4D28C/LD

7440530047

4.7

0.027

0.036

0.038

1.66

1.5

2.0

6 x 6.3 x 3

5.1 x 5.1 x 3

5.8 x 5.8 x 2.8

TYPICAL APPLICATION CIRCUITS

Figure 3—Step-Down White LED Driver Application

Figure 4— Step-up/down White LED Driver Application

MP24183 Rev. 1.0

8/28/2008

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MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

Figure 5— Step-up White LED Driver Application

MP24183 Rev. 1.0

8/28/2008

www.MonolithicPower.com

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MP24183 – 1A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

PACKAGE INFORMATION

3mm x 3mm QFN10

2.90

3.10

0.30

0.50

1.45

1.75

PIN 1 ID

SEE DETAIL A

PIN 1 ID

MARKING

0.18

0.30

2.25

2.55

2.90

3.10

PIN 1 ID

INDEX AREA

0.50

BSC

TOP VIEW

BOTTOM VIEW

PIN 1 ID OPTION A

R0.20 TYP.

PIN 1 ID OPTION B

R0.20 TYP.

0.80

1.00

0.20 REF

0.00

0.05

SIDE VIEW

DETAIL A

NOTE:

2.90

1.70

1) ALL DIMENSIONS ARE IN MILLIMETERS.

0.70

0.25

2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.

3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.

4) DRAWING CONFORMS TO JEDEC MO-229, VARIATION VEED-5.

5) DRAWING IS NOT TO SCALE.

2.50

0.50

RECOMMENDED LAND PATTERN

NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third

party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not

assume any legal responsibility for any said applications.

MP24183 Rev. 1.0

8/28/2008

www.MonolithicPower.com

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

MP24183DQ [MPS]

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