Single Phase Full-Wave Motor Driver with Built-in Hall Sensor for Fan Motor

Transcription

1 Single Phase Full-Wave Motor Driver with Built-in Hall Sensor for Fan Motor The AM309 is a single phase full-wave fan motor driver IC with built-in hall sensor. Rotation speed curve could be adjusted by DC-PWM intput. The device contains rotating speed pulse detection output (FG), output soft switching, lock protection and thermal shutdown protection. Maximum output current is 1A. The device is available in TSOT26-FL package. Applications Single Phase DC Motor. Features 1) Built-in hall-effect sensor. 2) Operation voltage 2.0 to 6.5V. 3) RPM Curve adjust 4) Lock detection/automatic restart circuit. 5) Rotating speed pulse signal (FG) output. 6) Built-in turbo start up (overcome friction). 7) Soft switched drive for silent application. 8) Thermal shutdown protection (TSD). 9) Auto gain control function (AGC). 10) Built-in Hall Signal Offset Cancellation Technical Absolute Maximum Ratings (Ta = 25 ) Parameter Symbol Limits Unit Supply voltage V CC 8 V Output maximum current I O(MAX) 1000* ma Output continuous current I O(CONT.) 400 ma FG single output voltage V FG 8 V FG single output current I FG(SINK) 10 ma Power dissipation Pd 581** mw Operate temperature range T opr -20~+90 Storage temperature range T stg -40~+150 Junction temperature Tjmax 150 * This value is not to exceed Pd. ** Reducing by 4.65 mw/ over 25 (On 114.3mm X 76.1mm X 1.6mm single layer board) Exceeding the absolute maximum ratings may cause permanent damage. Recommended Operating Conditions (Set the power supply voltage taking allowable dissipation into considering) Parameter Symbol Min Typ Max Unit Operating supply voltage range V CC 2.0~6.5 V - 1 -

2 Electrical Characteristics (Unless otherwise specified, Ta = 25, V CC = 5V) Parameter Symbol Limit Min Typ Max Unit Conditions Supply current I CC ma No load on output DC-PWM OSC H voltage Vosch V Peak voltage of triangular OSC L voltage Voscl V wave (OSC) inside IC OSC frequency Fosc KHz Output Output voltage V O V I O =200mA (Upper + Lower) FG low voltage V FGL V I FG(sink) = 3mA FG leakage current I FGL μa V FG = 5V Magnetic characteristics Operate point B OP G Release point B RP G Hysteresis B HYST G Lock protection Lock detection ON time T ON sec Lock detection OFF time T OFF sec - 2 -

3 Block Diagram Vcc 5 AGC Voltage Reference 6 FG Hall Sensor TSD Chopper Amplifier / Offset cancellation S/H Oscillator Comparator Lock Protection DC-PWM Logic Control Soft Switching Pre Driver H-Bridge Output Driver 4 3 Out1 Out2 2 1 GND DC-PWM Fig.1 Pin Definition and Description PIN No Pin Name Function 1 DC-PWM DC-PWM signal input terminal 2 GND Ground terminal 3 OUT2 Motor output terminal 4 OUT1 Motor output terminal 5 VCC Power supply terminal 6 FG FG signal output terminal DC-PWM FG GND Vcc Out2 Out1 Fig.2 Pin assignment - 3 -

4 Magnetic Pole vs. Outputs Behavior Test conditions DC-PWM OUT1 OUT2 FG Mode B > B OP H L L (Output Tr : ON) H B < B RP L H Z (Output Tr : OFF) B > B OP L L L (Output Tr : ON) L B < B RP L L Z (Output Tr : OFF) B > B OP L L L (Output Tr : ON) - B < B RP L L Z (Output Tr : OFF) Z:Open drain output (High impedance) Note: DC-PWM at H or L. Please refer Fig.8 Operation mode Lock mode Supply magnetic direction Fig.3 Magnetic direction Hysteresis Characteristics Fig.4 Hysteresis - 4 -

5 Application Circuit DC voltage speed control Output DC-PWM duty is varied by input voltage. When input voltage level is low, output DC-PWM duty is low. The voltage range of output duty changes is between OSC L voltage and OSC H voltage. When the input voltage is around OSC L (about 0.4V), rotational speed of the motor may fluctuate because of the turbo start function operates repeatedly. The recommend voltage is higher than 0.6V. VCC DC- PWM GND Out2 FG VCC Out1 Pull-up resistor Connection of board D1 C1 ZD1 Option M Fig.6 DC voltage DC-PWM control Normally, reverse connection of power supply may damage the device. The IC has designed the (D1) diode in the IC circuit to protect reverse connection. The BEMF causes re-circulate current to power supply, when power-on or output changes. It may cause V CC terminal to raise voltage when there is a reverse current protection diode and there is no way to return current back to power supply. In such case, please take necessary measures like above. Connect a Zener diode (ZD1) between V CC and GND terminal not to exceed the absolute maximum rating voltage. Connect a capacitor (C1) between V CC and GND terminal to make a path of return current to power supply

6 Speed control DC voltage DC-PWM speed control Output ON duty is controlled by the input voltage to DC-PWM terminal, comparing with internal triangular wave (OSC). DC-PWM terminal voltage become higher, output ON duty become wide. DC-PWM voltage > OSC voltage : High side output ON DC-PWM voltage > OSC voltage : High side output OFF Fig.8 DC input speed control mode Setting example 1. Output ON duty 50% on Vcc=5V. DC-PWM setting voltage equation: Setting voltage = Voscl + [ ( Vosch - Voscl ) ( Target Duty ) / 100 ] = [ ( ) 50 / 100 ] = 1.0 V - 6 -

7 Lock Detection, Automatic Restart Circuit This IC detect the rotation of the motor by built-in hall signal, and adjust lock detection ON time (Ton) and lock detection OFF time (Toff) by the internal counter. These time (Ton, Toff) are showed below. Fig.9 Lock detect and auto restart motion Auto Gain Control (AGC) The AM309 is built-in a Hall sensor element to sense the magnetic flux density (B). The device offers fixed current to drive hall sensor, and utilize chopper amplifier circuit to cancel hall sensor offset. AGC technology with different distance and magnetic force offers stable hall signal. AGC setting by different VCC value. Output Soft Switching The AM309 device includes a soft-switching algorithm that controls the output switching slew rate for both output pins. As a result the AM309 device is ideal for use in applications requiring low audible switching noise and low EMI interference

8 Turbo start up function The turbo start-up output will work at DC-PWM Duty 100% in the first 2.5~3 FG cycle. The function characteristic is showed as blow. VCC PWM Input DC-PWM Voltage: 0.7~1.6 Out1 Out2 FG Power on Turbo start up time Fig.11 Turbo start up Output duty =PWM duty Power Sequence DC-PWM voltage need to equal or lower than Vcc while Fan is working. When Power off (Vcc=0V), DC-PWM need to off to avoid power from DC-PWM to Vcc. RPM Curve Adjust The RPM curve could be adjust by changing the DC voltage at DC-PWM pin. Normally the DC-PWM input can use two resistors to partial voltage to design the needed RPM curve. The DC-PWM voltage range is (Typ.) 0.4V~1.6V. The DC-PWM voltage should over 0.7V for application. The Fan speed controlled by DC-PWM input is showed as following. DC-PWM Pin two resistor application Vcc RPM Original RPM Curve DC-PWM 2V 2V 2V 5V Vcc - 8 -

9 Thermal Information θja junction-to-ambient thermal resistance /W Ψjt junction-to-top characterization parameter 2.46 /W Θja is obtained in a simulation on a JEDEC-standard 1s0p board as specified injesd-51. The Θja number listed above gives an estimate of how much temperature rise is expected if the device was mounted on a standard JEDEC board. When mounted on the actual PCB, the Θja value of JEDEC board is totally different than the Θja value of actual PCB. Ψjt is extracted from the simulation data to obtain Θja using a procedure described in JESD-51, which estimates the junction temperature of a device in an actual PCB. The thermal characterization parameter,ψjt, is proportional to the temperature difference between the top of the package and the junction temperature. Hence, it is useful value for an engineer verifying device temperature in an actual PCB environment as described in JEDEC JESD When Greek letters are not available,ψjt is written Psi-jt. Definition: Tt Tj DFEINITION : jt Tj ( Tt ) / Pd Where : Ψjt (Psi-jt) = Junction-to-Top(of the package) C/W Tj= Die Junction Temp. C Tt= Top of package Temp at center. C Pd= Power dissipation. Watts Practically, most of the device heat goes into the PCB, there is a very low heat flow through top of the package, So the temperature difference between Tj and Tt shall be small, that is any error caused by PCB variation is small. This constant represents that Ψjt is completely PCB independent and could be used to predict the Tj in the environment of the actual PCB if Tt is measured properly

10 How to predict Tj in the environment of the actual PCB Step 1 : Used the simulated Ψjt value listed above. Step 2 : Measure Tt value by using Thermocouple Method We recommend use of a small ~40 gauge(3.15mil diameter) thermocouple. The bead and thermocouples wires should touch the top of the package and be covered with a minimal amount of thermally conductive epoxy. The wires should be heat-insulated to prevent cooling of the bead due to heat loss into wires. This is important towards preventing too cool Tt measurements, which would lead to the calculated Tj also being too cool. IR Spot Method An IR Spot method should be utilized only when using a tool with a small enough spot area to acquire the true top center hot spot. Many so-called small spot size tools still have a measurement area of 0~100+mils at zero distance of the tool from the surface. This spot area is too big for many smaller packages and likely would result in cooler readings than the small thermocouple method. Consequently, to match between spot area and package surface size is important while measuring Tt with IR sport method. Step 3 : calculating power dissipation by P (VCC Vo_Hi Vo_Lo ) x Iout + VCC x Icc Step 4 : Estimate Tj value by Tj= Ψjt x P+Tt Step 5: Calculated Θja value of actual PCB by the known Tj Θja(actual) = (Tj-Ta)/P

11 Maximum Power Dissipation (de-rating curve) under JEDEC PCB & actual PCB

12 Packaging outline --- TSOT26-FL Unit : mm D Sensor Location E E e e1 B B b b1 A A1 c1 c SECTION B-B With Plating SYMBOL MILLIMETERS INCHES Min. Max. Min. Max. A A b b c c D E E e 0.95 BSC BSC e BSC BSC

13 Application Note 1) Absolute maximum ratings This product is produced with strict quality control, but destroyed in using beyond absolute maximum ratings. Once IC destroyed, a failure mode cannot be defined (like short-mode or open-mode).therefore, physical security counter measure, like fuse, is to be given when a specific mode to be beyond absolute maximum rating is considered. 2) Connecting the power supply connector backward Connecting of the power supply in reverse polarity can damage IC. Take precautions when connecting the power supply lines. An external direction diode can be added. 3) Power supply line The BEMF causes re-circulate current to power supply, Please connect a capacitor between power supply and GND as a route of re-circulate current. And please determine the capacitance after confirmation that the capacitance does not causes any problems. 4) GND potential The GND terminal should be the location of the lowest voltage on the chip. 5) Thermal design Use a thermal design that allows for a sufficient margin in light of the power dissipation in actual operating conditions. 6) Mounting failures Mounting failures, such as misdirection or miss-mounts, may destroy the device. The electrical short caused by falling particle, between outputs; power supply and output; or output and ground, may damage the device. Inter-pin shorts and mounting errors. 7) Actions in strong electromagnetic field Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to malfunction. 8) ASO When using the IC, set the output transistor so that it does not exceed absolute maximum rations or ASO

14 Condition of Soldering 1). Manual Soldering Time / Temperature < 3 sec / o C (2 Times) Test Results:0 fail/ 22 tested Manual Soldering count:2 Times 2). Re-flow Soldering (follow IPC/JEDEC J-STD-020D) Classification Reflow Profile Profile Feature Pb-Free Assembly Average ramp-up rate (T L to T P ) 3 o C/second max. Preheat - Temperature Min (Ts min) 150 o C - Temperature Max (Ts max) 200 o C - Time (ts) from (Tsmin to Tsmax) seconds Ts max to T L - Temperature Min (Ts min) 3 o C/second max. Time maintained above: - Liquid us temperature (T L ) 217 o C - Time (t L ) maintained above TL seconds Peak package body temperature (Tp) /-5 o C Time with 5 o C of actual Peak 30 seconds - Temperature (tp) Ramp-down Rate 6 o C/second max. Time 25 o C to Peak Temperature 8 minutes max. Test Results:0 fail/ 32 tested Reflow count:3 cycles

15 Marking Identification EQWD27 Row1 Pin1 mark Row 1 Date & Lot number Week Year-A:0,B:1 J:9 E.g. 2012:C, 2013:D Lot No Device code : E = AM309 Explanation: EQWD27 E : AM309 QW: Production Serial number D: : Week