ACT111A | DigiCamel IC Datasheet

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ACT111A ACTIVE-SEMI | Alldatasheet

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Innovative PowerTM - 1 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Active-Semi Confidential―Do Not Copy or Distribute TYPICAL APPLICATION CIRCUIT ACT111A 4.8V to 30V Input, 1.5A LED Driver with Dimming Control

FEATURES

Up to 92% Efficiency
Wide 4.8V to 30V Input Voltage Range
100mV Low Feedback Voltage
1.5A High Output Capacity
PWM Dimming
10kHz Maximum Dimming Frequency
Thermal Shutdown
SOT23-6 Package

APPLICATIONS

High Brightness LED Driver
Architecture Detail Lighting
Constant Current Source
Hand-held Lighting
Automotive RCL, DRL, and Fog Lights
Indicators and Emergency Lighting
MR16 and other LED Bulb GENERAL DESCRIPTION The ACT111A is a high efficient LED driver employing current-mode buc k converter topology that supplies up to 1.5A from wide input voltage range from 4.8V up to 30V. The ACT111A is designed to operate as a constant source with 1.4MHz fixed frequency. ACT111A consists of a PWM control circuit, a high precision band-gap voltage reference, an oscillator, an error amplifier with internal compensation network and the N channel power MOSFET. An external sense resistor in series with the LED monitors output current allowing accurate current regulation, ideal for driving high current LEDs. The built-in fault condition protection circuits including current limiting, UVLO and thermal shutdown prevent itself from potentially faulty operation and burn-out. The ACT111A is ideal for single 1W to 5W LED drivers. With its ultra low feedback voltage, a low current ripple, high efficiency of up to 92% step- down power LED driver c an be easily composed of with additional several external components such as an inductor, a Schottky diode, a few resistors and capacitors. Rev 0, 14-Feb-11

ORDERING INFORMATION

PART NUMBER TEMPERATURE RANGE PACKAGE PINS PACKING ACT111AUS-T -40°C to 85°C SOT23-6 6 TAPE & REEL TOP MARK FRWE DIM IN SW FB G BST FRWE SOT23-6 ACT111AUS-T PIN NUMBER PIN NAME PIN DESCRIPTION 1 FB Feedback Input for regulating LED current. The voltage at this pin is regulated to 0.1V. An external resistor is connected from this pin to ground to sense the LED current. 2 G Ground. 3 BST Bootstrap pin. This provides power to the internal high-side N channel MOSFET gate driver. Connect a 2.2nF capacitor from the pin to SW pin. 4 SW Internal N channel power MOSFET source output pin. Connect it to one end of power inductor. 5 IN Power supply input. Bypass this pin with a 10µF ceramic capacitor to GND, placed as close to the IC as possible.

6 DIM

PWM signal input for dimming control. Apply PWM signal with amplitude greater than 2V to this pin. The device is enabled as DIM pin open and disabled when it is connected to G.

Rev 0, 14-Feb-11 Innovative PowerTM - 3 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Active-Semi Confidential―Do Not Copy or Distribute ABSOLUTE MAXIMUM RATINGSc PARAMETER VALUE UNIT IN to G -0.3 to 34 V SW to G -1 to VIN + 1 V BST to G VSW - 0.3 to VSW + 7 V FB to G -0.3 to +6 V Continuous SW Current Internally Limited A Junction to Ambient Thermal Resistance (θJA) 220 °C/W Maximum Power Dissipation 0.5 W Operating Junction Temperature -40 to 150 °C Storage Temperature -55 to 150 °C Lead Temperature (Soldering, 10 sec) 300 °C DIM to G -0.3 to +3 V PARAMETER SYMBOL TEST COND ITIONS MIN TYP MAX UNIT Input Voltage V IN 4.8 30 V VIN Turn-On Voltage Input Vo ltage Rising 4.0 4.4 4.7 V VIN UVLO Hysteresis 250 mV Supply Operation Current V FB = 0.2V 1 2 mA Switching Frequency 1.15 1.4 1.65 MHz Maximum Duty Cycle V FB = 0.08V 90 92 95 % Minimum On-Time 75 ns Effective FB Voltage 5V ≤ VIN ≤ 20V 97 102 107 mV FB Leakage Current 100 nA CC Current Limit Duty Cycle = 5% 1.8 2.4 3.0 A PWM DIM Frequency 10 kHz DIM Threshold Voltage DIM rising 1.66 V DIM Hysteresis DIM rising 100 mV DIM Input Leakage 1 µA High-Side Switch On-Resistance 0.3 Ω Low-Side Switch On-Resistance 15 Ω Thermal Shutdown Temperature 160 °C Thermal Hysteresis 10 °C

ELECTRICAL CHARACTERISTICS

(VIN = 12V, TA = 25°C, unless otherwise specified.) c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rati ng conditions for long periods m ay affect device reliability.

Rev 0, 14-Feb-11 Innovative PowerTM - 4 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Active-Semi Confidential―Do Not Copy or Distribute TYPICAL PERFORMANCE CHARACTERISTICS (TA = 25°C, unless otherwise specified.) Temperature (°C) FB Voltage (mV) FB Voltage vs. Temperature 100 101 102 -40 -20 0 20 40 60 80 100 120 Oscillator Frequency (MHz) Oscillator Frequency vs. Temperature 1.20 1.30 1.40 1.50 1.60 ACT111A-001 ACT111A-002 ACT111A-003 ACT111A-004 Efficiency vs. Load Current Efficiency (%) 0.1 1 10 Efficiency vs. Load Current Efficiency (%)

95 VIN = 12V

VOUT = 5V VOUT = 3.3V Duty Cycle Peak Current Limit (A) Peak Current Limit vs. Duty Cycle 0.0 0.5 1.0 1.5 2.0 2.5 0 20 40 80 100 ACT111A-005 Load Current (A) VIN = 24V VIN = 18V 0.1 1 10 Load Current (A) VIN = 24V VIN = 18V VIN = 12V Temperature (°C) -40 -20 0 20 40 60 80 100 120 3.0

Rev 0, 14-Feb-11 Innovative PowerTM - 5 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Active-Semi Confidential―Do Not Copy or Distribute (2) FIN FO VV VVD + fI )VV)(D1(L L FO +−= Δ (1) FUNCTIONAL BLOCK DIAGRAM FUNCTIONAL DESCRIPTION The ACT111A is a current-mode step-down 1.5A LED driver with no extra external compensation components. It has wide 4.8V to 30V input voltage range for a variety of power sources. The 100mV low feedback voltage and an external current sense resistor makes it deliver LED current programmable from 20mA to 700mA with efficiency up to 96%. The device contains an internal, low-resistance, high- voltage power MOSFET, and operates at a high 1.4MHz operating frequency to ensure a compact, high-efficiency design with excellent AC and DC performance. It is in a space saving SOT23-6 package. The ACT111A is a current mode regulator. It controls the inductor peak current by the feedback loop during each switching cycle. Therefore, it improves loop dynamics. In steady state operation, a pulse from the oscillator starts a cycle to turn on the internal top MOSFET switch. Current in the switch and the external inductor ramps up. As the current level reaches the voltage level defined by the internal error amplifier output, the internal switch is turned off. The current in the inductor flows through the external Schottky diode. The inductor current is continuously adjusted by the internal error amplifier. In the ACT111A, the voltage to the FB pin compares to the internal accurate 100mV reference voltage to generate error signal. Therefore, as a current sense resistor in series with LED is connected to the FB pin, the LED current is well regulated. LED dimming can be performed by directly connecting a PWM signal (frequency rage from 0.1kHz to 10kHz) the DIM pin. If the DIM pin is unconnected or pulled high, the ACT111A operates normally. Inductor Selection The optimum inductor for a given application has to be chosen with operation condition. The inductor current waveform is a triangle with an average value equal to the load current in continuous conduction mode (CCM). The peak switch current is equal to the output current plus half the peak-to- peak inductor ripple current and is limited to around 1.8A to protect itself and power stage from overload condition. Therefore, the maximum output current to a load depends on the switch current limit, the inductor value, and the input and output voltages. The peak-to-peak inductor ripple current is usually controlled to 20%-30% of the output current and the inductor value is selected accordingly by: where f is 1.4MHz switching frequency of the ACT111A, V O is the output voltage, V F is the Schottky diode forward voltage drop (~0.4V), and D is switching duty cycle given by: The inductor’s RMS current rating must be greater than the maximum load current and its saturation current should be at least 30% higher. For high IN DIM FB G REFERENCE & THERMAL SHUTDOWN CONTROL PWM Comparator ILIM Comparator REGULATOR & UVLO OSCILLATOR COMPENSATION DRIVER CSA BST SW EA LOGIC

Rev 0, 14-Feb-11 Innovative PowerTM - 7 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Active-Semi Confidential―Do Not Copy or Distribute VDIM(MAX) (V) R1 (k Ω) R DIM (kΩ) 3.3 30 976 2 30 576 5 30 1470 The following equation determines resistor values: According to the equati on, Table 1 shows the respective resister values with different DC dimming voltage. VTB is 100mV, R1 is chosen to be 30kΩ. Table 1: Open LED Protection In case of LED failure, the ACT111A will operate at maximum duty cycle due to the feedback voltage drops to zero. This will results in the output voltage moving up. To prevent over voltage on the output, a Zener and a series resistor are used as shown in Figure 3 and Figure 6 (ZD1 and R4). Thermal Shutdown The ACT111A automatically turns off when the IC junction temperature exceeds 160°C, and reenables when the IC junction temperature drops by 10°C (typ). PC Board Layout To achieve good performance, it is extremely important to have optimized component placement and layout on PCB for a high switching frequency and high efficiency regulator. Here are recommendations for the layout: Place input capacitor to IN pin, inductor and diode to SW pin as close as possible to reduce the voltage ringing at these pins. Place the current sense resistor close to FB pin. Minimize ground noise by connecting high current ground returns, the input capacitor ground lead, and the output filter ground lead to a single point (star ground configuration). There are two power loops in normal operation, one is formed when the SW is high and the high current flows through input capacitor, internal MOSFET, inductor, LEDs, R SENSE to ground. The other loop is through inductor, LEDs, R SENSE, ground to diode. Make these loop areas as small as possible to minimize noise interaction. SW pad is a noisy node switching from VIN to GND. It should be isolated away from the rest of circuit for good EMI and low noise operation. FB FBMAXDIM DIM V VV1RR −= (7)

1 U1 IC, ACT111A Active-Semi

2 C1 Capacitor Tantalum, 47µF/25V, E Case AVX

3 C2 Capacitor, Ceramic, 0.01µF/50V, 0603 POE

4 C3 Capacitor, Ceramic, 100pF/25V, 0603 POE

5 C4 Capacitor Tantalum, 47µF/16V, D Case AVX

6 D1 - D4 Diode Schottky, 40V/1A, SS14, SMA PANJIT

7 D5 Schottky Barrier Rectifier, SR24, 40V/2.0A, SMB PANJIT 8 ZD1 Diode Zener, GLZ13A, 13V, 0.5W, MINI-MELF PANJIT

9 R1 Meter Film Resistor, 30k Ω, 0603, 5% TY-OHM

10 R2 Meter Film Resistor, 0.28 Ω, 1206, 1% TY-OHM

11 R4 Meter Film Resistor, 510 Ω, 1206, 5% TY-OHM

12 L1 SMD Power Inductor, SR0604100ML, 10µH, ±20% QianRu

Table 2: Bill of Material

Rev 0, 14-Feb-11 Innovative PowerTM - 11 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Active-Semi Confidential―Do Not Copy or Distribute Table 3: Bill of Material ITEM REFERENCE DESCRIPTION MANUFACTURER

2 C1 Capacitor Tantalum, 47µF/35V, E Case AVX

3 C3 Capacitor, Ceramic, 0.01µF/50V, 0603 POE

4 C4 Capacitor, Ceramic, 100pF/25V, 0603 POE

5 C5 Capacitor Tantalum, 10µF/25V, D Case AVX

6 D1 Schottky Barrier Rectifie r, SR24, 40V/2.0A, SMB PANJIT 7 ZD1 Diode Zener, GLZ21A, 21V, 0.5W, MINI-MELF PANJIT

8 R1 Meter Film Resistor, 30k Ω, 0603, 5% TY-OHM

9 R2 Meter Film Resistor, 0.14 Ω, 1206, 1% TY-OHM

10 R4 Meter Film Resistor, 1k Ω, 1206, 5% TY-OHM

11 L1 SMD Power Inductor, SR0604100ML, 10µH, ±20% QianRu

Rev 0, 14-Feb-11 Innovative PowerTM - 12 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Active-Semi Confidential―Do Not Copy or Distribute PACKAGE OUTLINE SOT23-6 PACKAGE OUTLINE AND DIMENSIONS D b E e A c L 0.2 θ SYMBOL DIMENSION IN MILLIMETERS DIMENSION IN INCHES MIN MAX MIN MAX A - 1.450 - 0.057 A1 0.000 0.150 0.000 0.006 A2 0.900 1.300 0.035 0.051 b 0.300 0.500 0.012 0.020 c 0.080 0.220 0.003 0.009 D 2.900 BSC 0.114 BSC E 1.600 BSC 0.063 BSC E1 2.800 BSC 0.110 BSC e 0.950 BSC 0.037 BSC e1 1.900 BSC 0.075 BSC L 0.300 0.600 0.012 0.024 θ 0° 8° 0° 8° Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. User s should evaluate each product to make sure that it is suitable for their applicat ions. Active-Semi products are not intended or authorized for use as critical components in life-support dev ices or systems. Active-Semi, Inc. does not assume any liability arising out of the use of any product or circuit described in this datasheet, nor does it convey any patent license. Active-Semi and its logo are trademarks of Active-Semi, Inc. For more information on this and other products, contact sales@active-semi.com or visit http://www.active-semi.com. is a registered trademark of Active-Semi.

Product Information

ACT111A specifications and overview.

Summary

4.8V to 30V Input, 1.5A LED Driver with Dimming Control Rev 0, 14-Feb-11

Description

4.8V to 30V Input, 1.5A LED Driver with Dimming Control Rev 0, 14-Feb-11

Source title ACT111A Datasheet(PDF) - Active-Semi, Inc

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