AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 1 -
Single Phase Full-Wave Motor Driver with
Built-in Hall Sensor for Fan Motor
The AM308 is a single phase full-wave fan motor driver IC with built-in hall sensor. Rotation speed
can be controlled by PWM input signal. 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) Direct PWM speed control.
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
11) Stand by Mode (PWM=L>70ms)
Absolute Maximum Ratings (Ta = 25℃)
Parameter Symbol Limits Unit
Supply voltage VCC 8 V
Output maximum current IO(MAX) 1000* mA
Output continuous current IO(CONT.) 400 mA
FG single output voltage VFG 8 V
FG single output current IFG(SINK) 10 mA
Power dissipation Pd 581** mW
Operate temperature range Topr -20~+90 ℃
Storage temperature range Tstg -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 VCC 2.0~6.5 V
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 2 -
Electrical Characteristics
(Unless otherwise specified, Ta = 25℃, VCC = 5V)
Parameter Symbol Limit
Unit Conditions Min Typ Max
Supply current ICC1 - 10 20 uA PWM=0
ICC2 0.3 0.5 mA PWM under 5%
ICC3 3 6 mA No load on output
ICC Condition (PWM frequency at 25KHz)
PWM duty of ICC1 DICC1 1 1.5 %
PWM duty of ICC2 DICC2 5 7.5 %
PWM
Input H level VPWMH 2.5 - VCC V
Input L level VPWML 0 - 0.7 V
Input frequency FPWM 0.03 - 50 kHz
Output
Output voltage VO - 0.25 0.35 V IO=200mA (Upper + Lower)
FG low voltage VFGL - 0.2 0.3 V IFG(sink) = 3mA
FG leakage current IFGL - - 10.0 μA VFG = 5V
Magnetic characteristics
Operate point BOP - 30 50 G
Release point BRP -50 -30 - G
Hysteresis BHYST - 60 100 G
Lock protection
Lock detection ON time TON 0.35 0.50 0.65 sec
Lock detection OFF time TOFF 3.5 5.0 6.5 sec
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 3 -
Block Diagram
Hall SensorChopper
Amplifier /
Offset
cancellation
AGC
S/H Comparator
Voltage
Reference
Logic
Control
Soft
Switching
Pre
Driver
H-Bridge
Output
Driver
PWM
Lock
ProtectionOscillatorTSD
4
3
12
5
6
Vcc
GND PWM
Out2
Out1
FG
Vcc
500KΩ
Fig.1
Pin Definition and Description
PIN No Pin Name Function
1 PWM 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
Fig.2 Pin assignment
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 4 -
Magnetic Pole vs. Outputs Behavior
Test conditions PWM OUT1 OUT2 FG Mode
B > BOP H
H L L (Output Tr : ON)
Operation mode B < BRP L H Z (Output Tr : OFF)
B > BOP L
L L L (Output Tr : ON)
B < BRP L L Z (Output Tr : OFF)
B > BOP -
L L L (Output Tr : ON) Lock mode
B < BRP L L Z (Output Tr : OFF)
Z:Open drain output (High impedance)
Supply magnetic direction
Fig.3 Magnetic direction
Hysteresis Characteristics
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 5 -
Application Circuit
Direct PWM speed control
FAN speed is controlled by FAN controller PWM output. IC output PWM duty is changed directly
by input PWM signal. H level input is motor active; L level input is motor stop.
Connection of board
VCCGND
Out2 Out1
PWM FG
M
Pull-up resistor
VCC
PWM
ZD1
Option
C1D1
Fig.5 Direct 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 VCC 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 VCC and GND terminal not to exceed the absolute maximum rating
voltage. Connect a capacitor (C1) between VCC and GND terminal to make a path of return
current to power supply.
Speed control
Direct PWM speed control
Rotation speed of motor can be changed by controlling ON/OFF of the upper output
depending on duty of the signal input to PWM terminal.
Fig.7 Timing chart in PWM control
When the voltage input to PWM terminal applies H logic : normal operation
L logic : H side output is off
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 6 -
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
Only in Lock detection ON Time (Ton), motor will be rest ordinary motion by switching over of built-in
hall signal. This IC make the lock protection function off, when the PWM input keeps low level for
more than 70ms (typ.).
Fig.10 PWM input signal and lock protect function
Lock protect function does not work if PWM input frequency is slower than 15Hz (typ.)
So, please input faster frequency more than 30Hz.
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 7 -
Auto Gain Control (AGC)
The AM308 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 AM308 device includes a soft-switching algorithm that controls the output switching slew rate
for both output pins. As a result the AM308 device is ideal for use in applications requiring low
audible switching noise and low EMI interference.
Turbo start up function
The turbo start-up output will work at PWM Duty 100% in the first 2.5~3 FG cycle. The output duty
doesn’t depend on the PWM terminal input. The function characteristic is showed as blow.
Fig.11 Turbo start up
Power Sequence
PWM voltage need to equal or lower than Vcc while Fan is working. When Power off (Vcc=0V),
PWM need to off to avoid power from PWM to Vcc.
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 8 -
PWM Noise Immunity
The IC could mask the unexpected PWM noise to avoid trigger digital circuit to go into lock function.
The PWM noise mask ability is under duty 5% (Typ.) at frequency 25KHz.
FG
PWM
Noise
Power Saving
The IC power consumption (Icc1) is extremely low. Only spend 10uA (Typ.) when PWM is low.
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 9 -
● Thermal Information
θja junction-to-ambient thermal resistance 215.15℃/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-51-12.
When Greek letters are not available,Ψjt is written Psi-jt.
Definition:
TtTj
PTT dtjjt/)( DFEINITION :
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.
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 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
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 11 -
Maximum Power Dissipation (de-rating curve) under JEDEC PCB & actual PCB
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 12 -
Packaging outline --- TSOT26-FL Unit : mm
A1
E
A
D
Sensor Location
e
e1
E11.344
0.7
69
B B
With Plating
c1 c
b1
b
SECTION B-B
SYMBOL MILLIMETERS INCHES
Min. Max. Min. Max.
A 0.70 0.80 0.028 0.031
A1 0.35 0.45 0.014 0.018
b 0.30 0.50 0.012 0.020
b1 0.30 0.45 0.012 0.018
c 0.11 0.20 0.004 0.008
c1 0.11 0.15 0.004 0.006
D 2.70 3.10 0.106 0.122
E 3.40 3.80 0.134 0.149
E1 1.50 1.70 0.060 0.067
e 0.95 BSC 0.037 BSC
e1 1.90 BSC 0.075 BSC
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 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.
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 14 -
Condition of Soldering
1). Manual Soldering
Time / Temperature < 3 sec / 400 + 10 oC (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 (TL to TP) 3oC/second max.
Preheat
- Temperature Min (Ts min)
- Temperature Max (Ts max)
- Time (ts) from (Tsmin to Tsmax)
150oC
200oC
60-120 seconds
Ts max to TL
- Temperature Min (Ts min)
3oC/second max.
Time maintained above:
- Liquid us temperature (TL)
- Time (tL) maintained above TL
217oC
60-150 seconds
Peak package body temperature (Tp) 260 +0/-5oC
Time with 5oC of actual Peak
- Temperature (tp)
30 seconds
Ramp-down Rate 6oC/second max.
Time 25oC to Peak Temperature 8 minutes max.
Test Results:0 fail/ 32 tested Reflow count:3 cycles
AM308
Motor Driver ICs
http://www.amtek-semi.com SEP. 22001144 VV11..00
Specifications subject to change without notice - 15 -
Marking Identification
DPKD27
Pin1 mark
Row1
Row 1
Date & Lot number
Week
Year-A:0,B:1 … J:9
E.g. 2012:C, 2013:D
Lot No
Device code : D = AM308
Explanation:
EQWD27
D : AM308
PK: Production Serial number
D: 2013
27: Week