RT8723. Single-Phase Full-Wave Fan Motor Driver. Features. General Description. Ordering Information RT8723. Applications. Marking Information

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1 RT873 Single-Phase Full-Wave Fan Motor Driver General Description The RT873 is a single-phase driver IC for fan motors. Rotation speed is controlled by supply voltage modulation and input signal. In the supply voltage control application, the fan speed slope is adjustable by the external voltage input. The RT873 provides several protection features including the standby mode, thermal shutdown, lock protection, the over-current protection and also the under-voltage protection. In standby and thermal shutdown mode, supply current is less than 100μA. The rotation frequency is generated by output. Ordering Information RT873 Note : Richtek products are : Package Type QU : UDFN-10L 3x3 (U-Type) Lead Plating System G : Green (Halogen Free and Pb Free) RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-00. Suitable for use in SnPb or Pb-free soldering processes. Features Low Supply Current Supply Voltage Control Fan Speed Adjustable Voltage Control Fan Speed Smart Force Start-Up Function Built-In Lock Protection Built-In Thermal Shutdown Built-In Over-Current Protection Built-In Frequency Generator with Output Signal Include Hall Bias Circuit RoHS Compliant and Halogen Free Applications Single Phase Fan Motor for Notebook or PC Marking Information M=YM DNN M= : Product Code YMDNN : Date Code Simplified Application Circuit Supply Voltage D1 Control Signal Pull-High Voltage Optional D R C1 RT873 OUT OUT1 HB Single Phase Brushless DC Motor M Floating SET H+ Hall H- 1

2 Pin Configurations (TOP VIEW) OUT H+ HB H OUT1 SET UDFN-10L 3x3 Function Pin Description Pin No. Pin Name Pin Function 1 OUT Output of H-Bridge for DC Motor. Power Supply Input. 3 H+ Positive Hall Input. 4 HB Hall Bias Voltage Output. 5 H Negative Hall Input. 6 SET Speed Slop Setting. 7 Output for Rotation Speed. This is an open drain output. 8 Signal Input. 9 OUT1 Output of H-Bridge for DC Motor. 10, 11 (Exposed Pad) Power Ground. The Exposed Pad should be soldered to a large PCB and connected to for maximum thermal dissipation. Function Block Diagram OUT H V CC OUT1 Control H Duty Gen. SET + - OSC Lock Protection TSD OCP Hall Bias HB

3 Operation Lockup Protection and Automatic Restart When the motor is locked, a lock detection circuit will detect this situation within a time duration (T ON, typical 0.5s), and the driver will try to restart the motor. If restart failed, the circuit will disable the output drivers regardless of the duty ratio of the to prevent the motor coil from burnout. After another time duration (T OFF, typical 5s), 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 input is pulled low. Quick Start and Standby Mode The operation mode of RT873 is determined by the external input. During the power up, if the input remains at a low-level voltage, the IC will enter the low power standby mode. If the input is kept at a high-level voltage or is a pulse signal, the IC will operate in the normal mode. On the other hand, during the normal operation, when the input is set to a low-level voltage for more than 1ms (typ.), the IC will enter the low-power standby mode. Once the input is pulled up again, the IC will be activated immediately for normal operations. In the standby mode, supply current is around 100μA. H+ H- t SD 1ms OUT1 Mode Normal Mode Standby Mode Normal Mode OUT I CC t ON t OFF t ON t OFF 3

4 Absolute Maximum Ratings (Note 1) Supply Input Voltage, (<300ns) V to 10V Hall Input Voltage Range, H+, H V to 6V SET Input Voltage, SET V to 6V Input Voltage, V to 6V Output Voltage, OUT1, OUT, V to 6V Maximum Output Current, OUT1, OUT A Power Dissipation, P T A = 5 C, θja = 150 C UDFN-10L 3x3 (One-Layer) W UDFN-10L 3x3 (Two-Layer) W Package Thermal Resistance (Note ) UDFN-10L 3x3 (One-Layer), θ JA C/W UDFN-10L 3x3 (One-Layer), θ JC C/W UDFN-10L 3x3 (Two-Layer), θ JA C/W UDFN-10L 3x3 (Two-Layer), θ JC C/W Junction Temperature C Lead Temperature (Soldering, 10 sec.) C Storage Temperature Range C to 150 C Recommended Operating Conditions (Note 4) Supply Input Voltage, V to 5.5V Hall Input Voltage, H+, H V to (V CC 1.1V) SET Input Voltage, SET V to V HB Input Voltage, V to V CC Junction Temperature Range C to 15 C Ambient Temperature Range C to 105 C Electrical Characteristics (V CC = 5V, T A = 5 C, Unless Otherwise specification) Operating Current Parameter Symbol Test Conditions Min Typ Max Unit I CC1 Rotation Mode and Lock Protection Mode ma Standby Current I CC Standby Mode ( = 0) μa Input Voltage High-Level V Mode Low-Level V Mode V CC V Input Frequency f PW Mode khz Input Leakage High-Level I PW M_H V PW M = V Mode Low-Level I PW M_L V PW M = Mode μa 4

5 Parameter Symbol Test Conditions Min Typ Max Unit Input-Output Gain G IO V OUT /H+ H- (Ratio) db Input Offset Voltage V HOFS ±6 mv Input Hysteresis Voltage V Hys ±5 ±10 ±15 mv Output Voltage V OUT I OUT = 50mA V Pin Low Voltage V I = 5mA V Pin Leak Current I V = V CC μa Hall Bias Voltage V HB I HB = 5mA V SET Input Leakage High-Level I SET_H V SET = V Mode Low-Level I SET_L V SET = Mode μa Lock Detection On-Time T ON s Lock Detection Off-Time T OFF s Thermal Shutdown C Thermal Shutdown Hysteresis C Supply Voltage Threshold V CC_TH V Quick Start Standby Detection Time t SD ms Quick Start Enable Time t QS μs 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. θ JA is measured at T A = 5 C on a high effective thermal conductivity one/two-layer test board per JEDEC 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. 5

6 Typical Application Circuit Supply Voltage D1 Control Signal Pull-High Voltage Floating Optional D R C1 RT873 OUT SET 10, 11 (Exposed Pad) OUT1 9 HB 4 Single Phase Brushless DC Motor H+ 3 Hall H- 5 M Figure 1. Fan Speed Controlled by Direct Input, it's known as Mode. Supply Voltage Optional D1 Floating Pull-High Voltage Floating D R C1 10, 11 (Exposed Pad) RT873 OUT SET OUT1 9 HB 4 Single Phase Brushless DC Motor H+ 3 Hall H- 5 M Figure. Fan Speed Controlled by Supply Voltage, it's known as Mode. Supply Voltage D1 Floating Pull-High Voltage Optional D R C1 RT873 OUT OUT1 9 Single Phase Brushless DC Motor M 10, 11 (Exposed Pad) HB R1 6 SET R R1 + R = 100k HB 4 H+ 3 Hall H- 5 Figure 3. Fan Speed Controlled by Supply Voltage with Slop Setting, it's known as ADJ Mode. 6

7 Application Information Speed Control The motor speed can be controlled by the supply voltage and external input pin. When the SET pin input is fixed at a voltage level, the motor speed will be controlled by the supply voltage. In ADJ Mode application, the RT873 provides the function to adjust the motor speed slope of the supply voltage region. Input the SET pin voltage will slow down the speed at the lower supply voltage by modulating the output switching duty, and the switching output frequency is equal to internal clock, f INT_CLK. When the SET pin input is floating, the motor speed will be controlled by the external input, as in mode. When the input is fixed at a high level voltage or floating, the motor will rotate with full speed, as in mode. When the input is fixed at a low level voltage, the motor will decelerate to stop. When a switching signal is sent as the input, the duty ratio of the input signal will be input to adjust the switching duty ratio to the output drivers. The switching frequency of the output drivers is dependent on the input frequency. Thermal Shutdown The RT873 provides a thermal shutdown function to prevent overheating due to excessive power dissipation. The function shuts down the switching operation when the junction temperature exceeds 160 C. Once the junction temperature cools down by around 30 C, the main converter will automatically resume switching. Over-Current Protection The RT873 includes an Over-Current Protection (OCP) feature to prevent the large supply current form supply voltage to output. When the over-current occur, the circuit will disable the output and the motor rotor will stop. After a time duration (T OFF, typical 5s), the IC will automatically try to restart the motor. If the supply current is still larger, the output will be shut down immediately. Speed (rpm) SET = 0.1V 1.8V 4.6V 5V Figure 4. Fan Speed Controlled by Supply Voltage Speed (rpm) SET Floating SET = HB 0% Duty (%) 100% Figure 5. Fan Speed Controlled by External Input Duty Speed Control The motor speed can be controlled by the external signal at pin and the supply input voltage. When a signal is provided to the pin, the driver output will follow the duty ratio of the input signal. The switching frequency of the driver is dependent on the input frequency. Therefore, the motor speed is controlled by the signal. The available input frequency range is from khz to 50kHz. When the input is fixed at a high-level voltage (>1.8V) or floating, the motor will rotate with full speed. When the input is fixed at a lowlevel voltage (<0.7V), the motor will decelerate to stop. In standby mode, the supply current can be reduced to 100μA. 7

8 Quick Start Function If the is pulled low for a delay time, t SD, the RT873 will enter standby mode. Once a signal is detected, the RT873 will provide outputs after a delay time, t QS. Standby OUT t SD Figure 6 Force Start-Up Control The motor speed is controlled by the external PMW signal. In order to successfully start the motor with lower duty, a start-up mechanism is applied to check if output duty from the external signal can drive the motor to rotate in a period (0.4 x t ON, typ. 0.s). If it cannot drive the motor to rotate because of its low duty, an internal signal with higher duty will be adopted to drive the motor. The internal duty varies according to input voltage (V CC 3.5V, duty = 50%; V CC < 3.5V, duty = 100%). Standby OUT t QS Figure 7 _TH = 3.5V OUT External (Lower Duty) 50% Duty External (Lower Duty) 0.4 x t ON (typ. 0.s) Max. ~0.6 x t ON (typ. 0.3s) Figure 8. Forced Start-Up when > _TH _TH = 3.5V OUT External (Lower Duty) Output = External (Lower Duty) 0.4 x t ON (typ. 0.s) Max. ~0.6 x t ON (typ. 0.3s) Figure 9. Forced Start-Up-1 when _TH 8

9 Output when Motor is in the Lock State Hall_Comp Lock Detection On-Time 0.5s Lock Detection Off-Time 5s Figure 10. Output when Motor is in the Lock State Hall_Comp Lock Detection On-Time 0.5s Lock Detection Off-Time 5s Figure 11. Output when Motor is in the Lock State-1 Truth Table H+ H OUT1 OUT Mode H L H L Z (Output : OFF) H L H L H L (Output : ON) H L L L Z (Output : OFF) L L H L L L (Output : ON) Operation Mode H L L L Z (Output : OFF) -- L H L L Z (Output : OFF) Lock Mode L L L Z (Output : OFF) Standby Mode 9

10 Thermal Considerations 3.0 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 : P D(MAX) = (T J(MAX) T A ) / θ JA where T J(MAX) is the maximum junction temperature, T A is the ambient temperature, and θ JA is the junction to ambient Maximum Power Dissipation (W) Two-Layer PCB One-Layer PCB thermal resistance. Ambient Temperature ( C) For recommended operating condition specifications, the maximum junction temperature is 15 C. The junction to ambient thermal resistance, θ JA, is layout dependent. For UDFN-10L 3x3 package, the thermal resistance, θ JA, is 0.48 C/W on a standard JEDEC 51-3 one-layer thermal test board. For UDFN-10L 3x3 package, the thermal resistance, θ JA, is.6 C/W on a standard JEDEC 51-3 two-layer thermal test board. The maximum power dissipation at T A = 5 C can be calculated by the following formula : Figure 1. Derating Curve of Maximum Power Dissipation P D(MAX) = (15 C 5 C) / (06.9 C/W) = 0.48W for UDFN-10L 3x3 package (One-Layer) P D(MAX) = (15 C 5 C) / (44. C/W) =.6W for UDFN-10L 3x3 package (Two-Layer) The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θ JA. The derating curve in Figure 1 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. 10

11 Outline Dimension 1 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 A A b D D E E e L U-Type 10L DFN 3x3 Package Richtek Technology Corporation 14F, No. 8, Tai Yuen 1 st Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863) 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. 11