® RT4531 Dual Channel 10s2p WLED Drivers General Description Features The RT4531 is a dual-channel current source with highefficiency asynchronous boost converter for backlight application. The RT4531 has built-in 1.5A/36V power MOSFET and two high current-matching capability current sink, so RT4531 can drives up 10s2p white LED. The RT4531 can allow very low voltage headroom control, therefore to improve LED strings efficiency effectively. Input Voltage Range : 2.5V to 5.5V Internal Soft-Start, UVLO, OTP, OCP, OVP μA Typical Shutdown Current : < 1μ 1MHz Switching Frequency Drives Up to 10 WLEDs in Two Strings Independent PWM Dimming and 1-Wire Dimming Control PWM Dimming Frequency from 20k to 100kHz Up to 10 Bit Dimming Resolution LED Current Accuracy ± 2% ( > 5mA) LED Current Matching ± 2% ( > 5mA) Built-in IFB1/IFB2 pin OVP, Short Protection, and Un-Use Detection The RT4531 supports both PWM dimming and 1-wire digital dimming interface and it can realize 10 bit brightness code programming. The RT4531 provides complete protection functions such as input Under-Voltage Lockout (UVLO), Over-Current Protection (OCP), Output Over Voltage (OVP) and OverTemperature Protection (OTP). Ordering Information The RT4531 is available in the WL-CSP-9B 1.35x1.35 (BSC) package. RT4531 Package Type WSC : WL-CSP-9B 1.35x1.35 (BSC) Applications Note : Smart Phones Probable Instruments Backlight for Small and Media Form Factor LCD Display with Single-cell Battery Input Richtek products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Simplified Application Circuit L VIN C1 C3 R1 PWM Dimming RT4531 EN PWM DS4531-00 December 2015 2P10S WLEDs IFB1 IFB2 ISET GND AGND Copyright © 2015 Richtek Technology Corporation. All rights reserved. … Enable SW … VIN C2 R2 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT4531 Pin Configurations Marking Information (TOP VIEW) IFB2 33 : Product Code ISET A1 PWM B1 33W A2 A3 IFB1 B2 B3 GND C3 SW W : Date Code AGND C1 C2 VIN EN WL-CSP-9B 1.35x1.35 (BSC) Functional Pin Description Pin No. Pin Name Pin Function A1 ISET Full-Scale LED Current Set Pin. Connecting a resistor to the pin programs the full-scale LED current. A2 IFB2 Single Output 2 for Backlight LED. A3 IFB1 Single Output 1 for Backlight LED. B1 PWM Enable Control, and PWM Dimming Signal Input. B2 AGND Analog Ground. B3 GND Power Ground. C1 EN Enable Control, and 1-Wire Dimming Signal Input. C2 VIN Supply Input Pin. C3 SW Switch Node of Boost Converter. Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS4531-00 December 2015 RT4531 Function Block Diagram OSC UVLO VIN OTP OVP SW BL PWM/Drv DC to DC Core EN Control Logic PWM Logic GND AGND OCP PWM FB OVP ISET ISET MINFB Current Source/ FB Short Detect IFB1 IFB2 Operation The RT4531 is a high efficiency solution with 10S2P string for backlight applications. The RT4531 optimizes the feedback regulation voltage to provide high efficiency and also keep high current matching. The RT4531 can receive either the 1-wire dimming at EN pin or PWM dimming at PWM pin for brightness dimming. If the 1-wire dimming is selected, the PWM pin should be kept high; If the PWM dimming is selected, the EN pin should be kept high. OCP Protection The RT4531 features a 1.5A OCP. The driver provides cycle-by-cycle current limit function to control the current on power switch. The boost switch turns off when the inductor current reaches this current threshold and it remains off until the beginning of the next switching cycle. This protects the RT4531 and external component under overload conditions. OTP Protection The OTP function will disable boost and current source when the junction temperature exceeds 150°C. Then restart to soft-start when the junction temperature is smaller than 135°C. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS4531-00 December 2015 OVP Protection The OVP function monitors the SW pin's voltage. Once it exceeds OVP threshold = 36.5V twice, the boost and current source will be latched off. Until PWM or EN go high from low again, the latch state will be released. 1-wire Brightness Dimming The RT4531 is built-in a 10-bit resolution brightness control. The EN pin features a simple 1-wire interface to allow digital brightness control. If the 1-wire dimming is needed, signals of a specific pattern should be input detection window into EN pin; Otherwise, PWM pin need to be enabled.(refer to Timing Diagram1 for Continuous Coding).The Register Program and register map give an overview of the protocol used by RT4531. PWM Brightness Dimming Besides programmable built-in 1-wire backlight LED current control, the RT4531 features a built-in PWM dimming current control by PWM pin, offering a linear current dimming by external clock source. In order to guarantee the PWM dimming resolution, recommending PWM dimming frequency have to be operated at range of 20kHz to 100kHz. is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT4531 Absolute Maximum Ratings (Note 1) Supply Voltage, VIN ------------------------------------------------------------------------------------------------------LED Switching Voltage, SW -------------------------------------------------------------------------------------------LED Current Source Voltage, IFB1, IFB2 ---------------------------------------------------------------------------Digital Clock Control Pin, EN, PWM --------------------------------------------------------------------------------Other Pins, ISET ---------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C WL-CSP-9B 1.35x1.35 (BSC) -----------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WL-CSP-9B 1.35x1.35 (BSC), θJA -----------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) ---------------------------------------------------------------------------------------------MM (Machine Model) ----------------------------------------------------------------------------------------------------- Recommended Operating Conditions −0.3V to 6V 38V −0.3V to 6V −0.3V to 6V −0.3V to 6V 1.22W 81.5°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 4) Supply Input Voltage, VIN ------------------------------------------------------------------------------------------------ 2.5V to 5.5V Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 3.6V, CIN = 2.2μF, COUT = 1μF, L = 4.7μH, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Power Supply UVLO VUVLO VIN falls -- 2.2 2.3 V UVLO Hysteresis Voltage VUVLO VIN rises after UVLO 30 50 200 mV VIN Supply Current IQ EN = High, Non-switching -- 1.2 -- mA VIN Shutdown Current ISHDN VIN = 5V -- 1 -- A Thermal Shutdown TSD -- 150 -- C -- 15 -- C IFBx = 20mA 2 -- 2 % IFBx = 20mA -- 1 2 % IFBx = 500A IFBx = 20mA, measured on IFBx pin which has a lower voltage. -- 1 -- % 200 300 430 mV 0.88 1 1.12 MHz Thermal Shutdown Hysteresis Back Light LED Accuracy of Back Light Output Current 1/2 AIBL1, 2 Matching of Output Current MIBL BLED Sense Voltage 1/2 VDSBL Back Light Switching Frequency f blosc Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS4531-00 December 2015 RT4531 Parameter Symbol Test Conditions Min Typ Max Unit Maximum Duty Cycle DMAX 90 95 -- % Back Light N-MOSFET Ron RDS(ON)_BLN 100 270 400 m Back Light Current Limit ILIM_BL After 5ms in soft-start 1.15 1.5 1.85 A Back Light Over Voltage Protection VBLOVP Close loop, VIN = 3.6V 35.5 36.5 37.5 V IFBx Pin Over Voltage Threshold VIFBXOVP Measure on IFBx pin -- 5 -- V One Wire Detection Delay tes_delay 300 -- -- s One Wire Detection Time tes_det 400 -- -- s One Wire Detection Window tes_win Measure from En low to high En pin low time in detection window Measure from En low to high, Fblosc = 1MHz -- 1 -- ms tstart 3 -- -- s tEOS 3 -- -- s Logic Control Start Time of Program Stream End Time of Program Stream High Time Low Bit tH_LB Logic 0 2 -- 180 s Low Time Low Bit tL_LB Logic 0 2x tH_LB -- 360 s High Time High Bit tH_HB Logic 1 2x tL_HB -- 360 s Low Time High Bit tL_HB Logic 1 2 -- 180 s Logic-Low VEN_L -- -- 0.4 Logic-High VEN_H 1.4 -- -- Logic-Low VPWM_L -- -- 0.4 Logic-High VPWM_H 1.4 -- -- EN Pull Low Resistor REN 280 400 520 k PWM Pull Low Resistor RPWM 280 400 520 k PWM Logic Low Width to Shutdown TSD_PWM PWM pin high to low, then shutdown 20 -- -- ms EN Logic Low Width to Shutdown TDS_EN EN pin high to low, then shutdown 2.5 -- -- ms EN Input Voltage PWM Input Voltage V V Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability. Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS4531-00 December 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT4531 Typical Application Circuit L 4.7µH VIN 2.5V to 5.5V C1 1µF R1 10 C3 1µF / 50V C2 … … EN B1 PWM PWM Dimming C3 RT4531 C1 Enable SW VIN C2 1µF 2P10S WLEDs A3 IFB1 A2 IFB2 ISET A1 GND AGND R2 63.4k B2 B3 Timing Diagram Timing Diagram1 for 1-wire Continuous Coding PWM Tstart Tes_delay Tes_det >300µs >400µs Tes_win Tstart Addr8 Addr7 =H =L D1 = L EOS Addr8 =L 3~360µs <1.23ms EN tH_LB < 2x tH_HB Detection Window tL_LB > 2x tL_HB Programming Code2 Programming Code1 Timing Diagram2 for Shutdown and then Reprogram PWM EN Detection Window Programming Code Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 > 2.5ms Shutdown Detection Window Programming Code is a registered trademark of Richtek Technology Corporation. DS4531-00 December 2015 RT4531 Typical Operating Characteristics Efficiency vs. Input Voltage 100 95 90 Efficiency(%) Efficiency (%) Efficiency vs. Output Current 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 85 80 ILED = 20mA ILED = 10mA 75 70 65 60 55 VIN = 3.6V, VOUT = 31V, 10s2p, 20mA/string VOUT = 31V, 10s2p 50 0 0 0 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.02 2.5 3 3.5 Output Current (A) Dimming Linearity 5 5.5 1.3 Switching Frequency (MHz)1 0.020 0.018 Output Current (mA) 4.5 Switching Frequency vs. Input Voltage 0.022 ILED1 ILED2 0.016 0.014 0.012 0.010 0.008 0.006 0.004 0.002 1.2 1.1 1.0 0.9 0.8 VIN = 3.6V 0.000 0.7 0 20 40 60 80 100 2.5 3 3.5 Dimming Duty Cycle (%) 4 4.5 5 5.5 Input Voltage (V) Switching Frequency vs. Temperature Sense Voltage vs. Output Current 1.13 0.315 1.08 0.314 Sense Voltage (V) Switching Frequency (MHz)1 4 Input Voltage(V) 1.03 0.98 0.93 0.313 0.312 0.311 0.88 0.310 -50 -25 0 25 50 75 100 Temperature (°C) Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS4531-00 December 2015 125 0 2.5 5 7.5 10 12.5 15 17.5 20 Output Current (mA) is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT4531 Application Information Register Program 1-Wire Interface (Device Address 0x2F) MSB LSB MSB LSB MSB LSB MSB Addr Addr Addr Addr Addr Addr Addr Addr Start D16 D15 D14 D13 D12 D11 D10 8 7 6 5 4 3 2 1 Address Data3 Data2 LSB D9 D8 D7 D6 D5 D4 D3 D2 D1 EOS Data1 Register Map Bit Label Reset Description D16 Ramp Up<2> 0 D15 Ramp Up<1> 0 D14 Ramp Up<0> 1 D13 Ramp Down<2> 0 D12 Ramp Down<1> 0 D11 Ramp Down<0> 1 D10 ILED<9> 0 MSB = sDAC<9> D9 ILED<8> 0 sDAC<8> D8 ILED<7> 0 sDAC<7> D7 ILED<6> 0 sDAC<6> D6 ILED<5> 0 sDAC<5> D5 ILED<4> 0 sDAC<4> D4 ILED<3> 0 sDAC<3> D3 ILED<2> 0 sDAC<2> D2 ILED<1> 0 sDAC<1> D1 ILED<0> 0 LSB = sDAC<0> [000] = 4s, [001] = 8s, [010] = 16s,[011] = 64s, [100] = 256s, [101] = 1.024ms, [110] = 2.048ms, [111] = 4.096ms [000] = 4s, [001] = 8s, [010] = 16s, [011] = 64s, [100] = 256s, [101] = 1.024ms, [110] = 2.048ms, [111] = 4.096ms Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 is a registered trademark of Richtek Technology Corporation. DS4531-00 December 2015 RT4531 Protection Actions EN High Source Current to FBx Soft-Start/ Normal Operation N SW > OVP for > 8cycles in 10msec Y Latch Off FBx < 30mV For 600µs? N Soft-Start /Normal Operation Y Y X = 2? Latch Off N FBx Turned Off Soft-Start/Normal Operation Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS4531-00 December 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT4531 LED Current Setting The dual channels of the RT4531 can provide up to 20 mA current each. No matter either 1-wire Brightness Dimming or PWM Brightness Dimming is selected, the full-scale current (current when dimming duty cycle is 100%) of each channel should be programmed by an external resistor RISET at ISET pin according to Equation 1. IFB V ISET KISET RISET IFBX IFB DAC code 1024 (2) Where : IFB : the full-scale LED current set by the RISET at ISET pin. Code : the 10-bit DAC code D1~D10 programmed by 1wire interface. To enter 1-wire dimming mode, the following digital pattern on the EN pin must be recognized by the IC when the IC starts from the shutdown mode. (1) Where : VISET = 1V, 1. Pull the EN pin high to enable the RT4531 and start the detection window for digital dimming. KISET = 1268 2. After the digital dimming detection delay time (T - Brightness Control es_delay, >300μs), drive the EN low for more than the detection time (T-es_det, >400μs). a. 1-wire Brightness Dimming The RT4531 is built-in a 10-bit resolution brightness control. The EN pin features a simple 1-wire interface to allow digital brightness control. If the 1-wire dimming is needed, signals of a specific pattern should be input detection window into EN pin; Otherwise, PWM pin need to be enabled.(refer to Timing Diagram1 for Continuous Coding).The Register Program and register map give an overview of the protocol used by RT4531.By the 1-wire Brightness Dimming, a master can program the 10-bit code D1(LSB) to D10(MSB) to any of 1024 steps with a single command. The programmed value will be stored in an internal register and set the dual-channel current according to Equation 2. The code will be reset to default value when the IC is shut down or disabled. VIN 2.5V to 5.5V 3. Pull the EN pin high after the detection time (>400μs) and before the detection window (Tes_win, <1.23ms), once the above 3 conditions are met, the IC immediately enters the 1-wire dimming mode. The digital dimming communication can start before the detection window expires. Once the dimming mode is selected, it cannot be changed without another start up. This means the IC needs to be shut down by pulling the EN low for 2.5ms and restarts. See the dimming mode detection and softstart for a graphical explanation. (see Timing Diagram1 for 1-wire Continuous Coding). L1 4.7µH C1 1µF D1 C3 1µF / 50V R1 10 … SW … VIN C2 1µF RT4531 2P10S WLEDs PWM 1-wire interface EN IFB1 IFB2 ISET GND AGND R2 63.4k Figure 1. RT4531 1-wire Dimming Typical Application Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 is a registered trademark of Richtek Technology Corporation. DS4531-00 December 2015 RT4531 b. PWM Brightness Dimming Besides programmable built-in 1-wire backlight LED current control, the RT4531 features a built-in PWM dimming current control by PWM pin, offering a linear current dimming by external clock source. In order to guarantee the PWM dimming resolution, recommending PWM dimming frequency have to be operated at range of 20kHz to 100kHz. When the PWM pin is constantly high, the dual channel current is regulated to full-scale according to Equation 1. it achieves LED brightness dimming. The relationship between the PWM duty cycle and IFBx current is given by Equation 3. IFBX IFB Duty % (3) Where : IFBX is the current of each current sink, IFB is the fullscale LED current, Duty is the duty cycle information detected from the PWM signals. The PWM pin allows PWM signals to reduce this regulation current according to the PWM duty cycle; therefore, VIN 2.5V to 5.5V L1 4.7µH C1 1µF D1 C3 1µF / 50V R1 10 … SW … VIN C2 1µF RT4531 2P10S WLEDs EN PWM IFB1 IFB2 ISET GND AGND R2 63.4k Figure 2. RT4531 PWM Dimming Typical Application OCP Protection Open LED Protection The RT4531 features a 1.5A OCP. The driver provides cycle-by-cycle current limit function to control the current on power switch. The boost switch turns off when the inductor current reaches this current threshold and it remains off until the beginning of the next switching cycle. This protects the RT4531 and external component under overload conditions. Open LED protection circuitry prevents IC damage as the result of LED disconnection. The RT4531 monitors the voltage at the LX pin during each switching cycle. The circuitry turns off the switch and shuts down the IC as soon as the LX voltage exceeds the VOVP threshold. The device remains in shutdown mode until it is enabled by toggling the EN pin logic. The RT4531 is designed to work with inductor values for 4.7μH (Taiyo NR4018T4R7M) and Cout values for 1μF/50V (Murata 0603/X5R)that the OVP is 37.5V typ. Generally, the VF of the backlight LED is about 3.1 to 3.3V, the RT4531 can support up to 10 LEDs and it would not be trigger OVP. OTP Protection The OTP function will disable boost and current source when the junction temperature exceeds 150°C. Then restart to soft-start when the junction temperature is smaller than 135°C. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS4531-00 December 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT4531 Thermal Considerations Layout Consideration For continuous operation, do not exceed absolute maximum operation junction temperature. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can be calculated by following formula : For best performance of the RT4531, the following guidelines must be strictly followed. PD(MAX) = ( TJ(MAX) − TA ) / θJA Where T J(MAX) is the maximum operation junction temperature, TA is the ambient temperature and the θJA is the junction to ambient thermal resistance. For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA, is layout dependent. For Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling. The GND and Exposed Pad should be connected to a strong ground plane for heat sinking and noise protection. Keep the main current traces as possible as short and wide. SW node of DC/DC converter is with high frequency voltage swing. It should be kept at a small area. It recommended to separate the ISET line and PWM line that avoid the PWM signal couple to ISET. WL-CSP-9B 1.35x1.35 (BSC) package, the thermal resistance, θJA, is 81.5°C/W on the standard JEDEC 517 four-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by following formula : PD(MAX) = (125°C − 25°C) / (81.5°C/W) = 1.22W for WL-CSP-9B 1.35x1.35 (BSC) package The maximum power dissipation depends on operating ambient temperature for fixed T J(MAX) and thermal resistance θJA. The derating curve in Figure 3 of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. Maximum Power Dissipation (W)1 1.6 Four-Layer PCB 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 3. Derating Curve of Maximum Power Dissipation Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 12 is a registered trademark of Richtek Technology Corporation. DS4531-00 December 2015 RT4531 Cout must be placed between GND and VOUT to reduce noise. R1 GND It recommended to separate the ISET line and PWM line that avoid the PWM signal couple to ISET. A1 A2 A3 IFB1 B1 B2 B3 GND … ISET … IFB2 PWM AGND EN C1 C2 C2 C3 SW VIN VBAT GND C3 R2 C1 CIN should be placed as closed as possible to VIN pin for good filtering. The inductor should be placed as close as possible to the switch pin to minimize the noise coupling into other circuits. SW node copper area should be minimized for reducing EMI. Figure 4. PCB Layout Guide Table 1. Recommended Components for Typical Application Circuit Reference Part Number Description Manufacture Schottky Diode SS0540 Schottky Diode PANJIT C1 EMK107BJ105MA-T Capacitor, Ceramic, 1F/16V X5R Taiyo Yuden R1 RC0603FR Resistor 63.4k, 1% YAGEO C2 GRM188R61H105KAAL MLCC,0603,X5R,50V,1uF Taiyo Yuden L NR4018T4R7M Inductor, 4.7H Taiyo Yuden C3 EMK107BJ105MA-T Capacitor, Ceramic, 1F/16V X5R Murata R2 RC0603FR Resistor 10, 1% YAGEO Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS4531-00 December 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 13 RT4531 Outline Dimension Symbol Dimensions In Millimeters Dimensions In Inches Min. Max. Min. Max. A 0.500 0.600 0.020 0.024 A1 0.170 0.230 0.007 0.009 b 0.240 0.300 0.009 0.012 D 1.300 1.400 0.051 0.055 D1 E 0.800 1.300 0.031 1.400 0.051 0.055 E1 0.800 0.031 e 0.400 0.016 WL-CSP-9B 1.35x1.35 (BSC) Richtek Technology Corporation 14F, No. 8, Tai Yuen 1st Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries. www.richtek.com 14 DS4531-00 December 2015