® RT8749 Digital Single-Phase Full Wave BLDC Fan Controller General Description Features The RT8749 is a highly integrated digital control IC for regulating single-phase full wave brushless DC (BLDC) fans at a programmed speed. The controller IC accepts a Pulse-Width Modulated (PWM) signal provided by the host, and decodes the duty-ratio of this PWM signal to 256 counts. The decoded duty-ratio will then be used for mapping to the programmed speed which is stored at the embedded flash memory. This speed profile can be programmed by users for different fan models and applications. By integrating a low RDS(ON) power MOSFET, the RT8749 minimizes component count on the PCB, thus reducing board size and cost of the motor/fan module. A frequency generator output is included to provide commutation signals to the host for the current rotating speed. The control IC also provides several protection features, including the peak-current limit, thermal shutdown protection, under-voltage protection and motor lock protection. An automatic restart circuit is designed to rotate the motor after the lock condition is released. Embedded 256 x 16 Bits Flash Memory Built-in Low RDS(ON) Power MOSFET External PWM Speed Control Wide Range External PWM Input Frequency (100Hz to 100kHz) Built-in Frequency Generator with Selectable FG or FG/2 Output Signal Built-in Peak Current Limit Built-in Motor Lock Protection and Automatic Restart Circuit Built-in Thermal Shutdown Protection Low Power Standby Mode (when PWM Input is Low) RoHS Compliant and Halogen Free Applications PC Fan Cooling Fan Single-Phase BLDC Motor Simplified Application Circuit RT8749 RNF OUT1 OUT2 BOOT1 VDD12 BOOT2 VDD VDD12M External Voltage Source (up to 12V) or V5DDA (V5DDA will disable at Standby Mode) RRNF V5DDD V5DDA V5DDA ROSC HN ROSC RFG HP FG PWM H GND VSS12 PWM Signal Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8749-00 January 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8749 Ordering Information Marking Information RT8749 2U= : Product Code Package Type QW : WDFN-16L 4x4 YMDNN : Date Code 2U=YM DNN Lead Plating System G : Green (Halogen Free and Pb Free) Note : Pin Configurations Richtek products are : (TOP VIEW) RoHS compliant and compatible with the current requireOUT1 BOOT1 VDD12M VDD12 VSS12 ROSC FG PWM ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. 1 2 3 4 5 6 7 8 GND 17 16 15 14 13 12 11 10 9 RNF OUT2 BOOT2 V5DDD GND V5DDA HN HP WDFN-16L 4x4 Functional Pin Description Pin No. Pin Name Pin Function 1 OUT1 Driver Output to Motor Terminal 1. 2 BOOT1 Bootstrap Supply for Motor Terminal 1. Connect a capacitor between this pin and OUT1. 3 VDD12M Input Power Source for H-Bridge Power MOSFET and Driver. 4 VDD12 Input Power Source for Internal Circuits. 5 VSS12 Ground of Internal Circuits. 6 ROSC Internal Oscillator Frequency Setting. Connect a resistor with low temperature coefficient between this pin and grand. 7 FG Frequency Output Signal with Open-Drain Logic. 8 PWM External PWM Input. With an internal pull-high resistor (200k). 9 HP Positive Input Signal of Hall Sensor. 10 HN Negative Input Signal of Hall Sensor. 11 V5DDA Regulated 5V Power Source for Hall Sensor. 12, 17 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 13 V5DDD Regulated 5V Power Source for Digital Circuit. 14 BOOT2 Bootstrap Supply for Motor Terminal 2. Connect a capacitor between this pin and OUT2. 15 OUT2 Driver Output to Motor Terminal 2. 16 RNF Output Current Detection. Connect to a resistor for H-Bridge over-current protection. Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8749-00 January 2015 RT8749 VDD12M V5DDA VSS12 VDD12 V5DDD HN HP Function Block Diagram V5DDD Prog Hall Intf Regulator BOOT1 Prog Intf Confi. Regs Digital Controller RNF Driver VDD12M V5DDD Duty-to-RPM PWM ROSC Flash Memory OUT1 BOOT2 OUT2 OSC Prog GND TSD OCP RNF FG Operation The highly integrated digital controlled fan controller RT8749 integrates several functions as follows : OTP The over-temperature protection block is activated when the junction temperature exceeds 150°C. It will be released when the temperature cools below 120°C. The hysteresis is 30°C. OCP The RT8749 features over-current protection function to protect the power MOSFET. Users need to add a resistor RRNF between the low-side N-MOSFET and GND. If over current protection is activated, the RT8749 will be shutdown. Hall Interface The Hall Interface receives hall element signal and then helps the RT8749 to recognize the fan position. The controller will control the current direction by recognized fan position. Oscillator The Oscillator generates the high accuracy 1MHz clock signal for PWM output frequency. The PWM output frequency is 31.25kHz typically. Digital Controller This block generates control signal to the driver for motor operation control. It controls the motor speed depending on duty to RPM converter, reference speed table and control parameters which are stored in the flash memory. Regulator The inherent voltage regulator generates regulated 5V output for V5DDD & V5DDA respectively. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8749-00 January 2015 Program Interface The Program Interface is used for programming flash memory purpose. is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8749 Absolute Maximum Ratings (Note 1) Supply Voltage, VDD12M, VDD12 ------------------------------------------------------------------------------------Output Current, IOUT -----------------------------------------------------------------------------------------------------Input Voltage, PWM -----------------------------------------------------------------------------------------------------Output Voltage, OUT1, OUT2, FG ------------------------------------------------------------------------------------BOOT1 to OUT1 ----------------------------------------------------------------------------------------------------------BOOT2 to OUT2 ----------------------------------------------------------------------------------------------------------FG Output Current --------------------------------------------------------------------------------------------------------Other Pins ------------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C WDFN-16L 4x4 ------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WDFN-16L 4x4, θJA ------------------------------------------------------------------------------------------------------WDFN-16L 4x4, θJC ------------------------------------------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) ---------------------------------------------------------------------------------------------- Recommended Operating Conditions −0.3V to 20V 0.95A −0.3V to 20V −0.3V to 20V −0.3V to 6V −0.3V to 6V 15mA −0.3V to 6V 3.38W 29.5°C/W 7.5°C/W 150°C 260°C −65°C to 150°C 4kV (Note 4) Supply Input Voltage, VDD12 ------------------------------------------------------------------------------------------- 5.8V to 14V Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VDD12 = 12V, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Power Dissipation Power Supply Current 1 IDD1 VPWM = 5V Without Loading -- -- 10 mA Power Supply Current 2 IDD2 VPWM = 0V -- -- 300 A UGATE On-Resistance (N-MOSFET) RDS(ON)_UGATE IOUT = 0.8A -- 0.4 0.8 LGATE On-Resistance (N-MOSFET) RDS(ON)_LGATE IOUT = 0.8A -- 0.4 0.8 V5DDA Output Voltage VDDA5 Load Current = 15mA 4.65 5 5.35 V V5DDD Output Voltage VDDD5 Load Current = 15mA 4.65 5 5.35 V -- 0.2 0.3 V 0.2 1.3 3 V Output Driver V5DDA & V5DDD Output FG Output FG Output Low Level Voltage VFG IFG = 5mA HP, HN Inputs Input Voltage Level VHP, VHN Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS8749-00 January 2015 RT8749 Parameter Symbol Test Conditions Min Typ Max Unit PWM Input PWM Input Voltage Level-High VPWMH 2.2 -- VDD12 Level-Low VPWML 0 -- 0.7 -- -- 50 A 0.1 -- 100 kHz VPW M = 0V V PWM Internal Pull-up Current IPWMIN PWM Input Frequency fPWMIN ROSC Frequency fROSC ROSC = 150k -- 1 -- MHz Current Limit ILIM RRNF = 0.25 -- 1 -- A Threshold Voltage VRNF 0.2 0.25 0.3 V -- 150 -- °C Current Limitation Thermal Protection Thermal Shutdown Temperature T SD 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. θJC is measured at the exposed pad of the package. 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. DS8749-00 January 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8749 Typical Application Circuit RT8749 16 RNF OUT1 15 OUT2 2 BOOT1 4 VDD12 BOOT2 14 V5DDD 13 3 VDD12M 11 V5DDA 1 1µF VDD 10µF External Voltage Source (up to 12V) or V5DDA (V5DDA will disable at Standby Mode) 6 RRNF 0.25 4.7µF V5DDA 4.7µF ROSC ROSC 150k RFG 10k 1µF HN 7 FG 8 PWM 10 H HP 9 12, 17 (Exposed Pad) GND 5 VSS12 PWM Signal Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS8749-00 January 2015 RT8749 Applications Information Speed Control The motor speed can be controlled by the external signal on the PWM pin or controlled by the input voltage on the VDD12 pin. (Switching input voltage is not allowed). When the RT8749 operates in input voltage control mode, the input voltage on VDD12 must be higher than 6V. When the PWM input is fixed at a high level voltage or floating, the motor will rotate with memory table's highest bit speed. When the PWM input is fixed at a low level voltage, the motor will decelerate to stop if the standby mode is enabled. Otherwise, the motor will rotate with memory table's lowest bit speed. When a switching signal is sent as the PWM input, the duty ratio of the input signal will be sampled and converted to a 8-bit code. This code is correspondent to an rotation speed which is stored in the embedded flash memory. The controller will regulate the fan motor's speed to this target speed by adjusting the switching duty ratio of the output drivers. It should be noted that the input PWM frequency is independent of the switching frequency of the output drivers. Hence, the input PWM frequency can be chosen within a wide range, from 100Hz to 100kHz, while keeping the output switching frequency at 31.25kHz. Peak Current Limitation The DC-link current of the inverter is limited to protect the power transistors and the motor. When the measured 0.25V current exceeds the current limit ( ), gate signals RRNF to the output drivers will be all turned off until the next switching cycle. Limit Current 0.25V RRNF DC-Link Current OCEN Output Gate Signal Desired ONTime Desired ONTime Figure 1 Motor Lock Protection and Automatic Restart Function When the motor is locked, a lock detection circuit will detect this situation within a time duration (TLOCK) ,and will disable the output drivers regardless of the duty ratio of the PWM to prevent the motor coil from burnout. After Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8749-00 January 2015 the time duration (TREL), the IC will automatically try to restart the motor. If the motor is still locked, then the iteration of the lock detection and restart will be repeated until the lock condition is released or the external PWM input is pulled low. is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8749 PWM Motor Speed FG TLOCK Lock Indicator TREL Figure 2. Sequence of Lock and Restart Low Power Standby Mode If the PWM input maintains a low level voltage for 20ms when the standby mode is enabled, the IC will enter the “low-power standby mode” until the PWM input is pulled up to a high level voltage. When RT8749 is at standby mode, V5DDA, OUT1 and OUT2 will be disabled. PWM 20ms Normal Mode Standby Mode Normal Mode Figure 3. Sequence of Low Power Standby Mode Over Temperature Protection The RT8749 includes an Over Temperature Protection (OTP) feature to prevent overheating due to excessive power dissipation. The OTP function shuts down the switching operation when the junction temperature exceeds 150°C. Once the junction temperature cools down by around 25°C, the main converter will automatically resume switching. To maintain continuous operation, the junction temperature should be kept below 125°C. Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 is a registered trademark of Richtek Technology Corporation. DS8749-00 January 2015 RT8749 For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA, is layout dependent. For RT8749 RFG VFG 60k Max. On : 60 VZ 6V Figure 4 FG Pull-up Resistance Design The RT8749's pull-up resistance will influence the FG pin's high and low voltage. The function block diagram in Figure 4 shows the FG pin's internal circuits. Note that 60kΩ have ±10% variation and 60Ω is the maximum on-resistance. The typical high and low level voltage of the FG pin can be calculated by the following formula : VFGHigh = VIN x (60k ±10%) / (RFG + 60k ±10%) + VZ x RFG / (RFG + 60k ±10%) VFGLow = VIN x 60 / (RFG +60) For VIN > 6V, VZ = 6V For VIN ≤ 6V, VZ = VIN WDFN-16L 4x4 package, the thermal resistance, θJA, is 29.5°C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : PD(MAX) = (125°C − 25°C) / (29.5°C/W) = 3.38W for WDFN-16L 4x4 package The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 5 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. Maximum Power Dissipation (W)1 VIN 4.00 Four-Layer PCB 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 Thermal Considerations For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : 0 25 50 75 100 125 Ambient Temperature (°C) Figure 5. Derating Curve of Maximum Power Dissipation PD(MAX) = (TJ(MAX) − TA) / θJA where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8749-00 January 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT8749 Outline Dimension 2 1 2 1 DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Symbol Dimensions In Millimeters Dimensions In Inches Min. Max. Min. Max. A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.150 0.250 0.006 0.010 D 3.900 4.100 0.154 0.161 D2 3.350 3.450 0.132 0.136 E 3.900 4.100 0.154 0.161 E2 2.650 2.750 0.104 0.108 0.450 e L 0.350 0.018 0.450 0.014 0.018 W-Type 16L DFN 4x4 Package 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 10 DS8749-00 January 2015