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ST1115C/ST1115D
Version Issue Date File Name Total Pages : A.005 : 2004/06/30 : SP-ST1115CD-A.005.doc : 13
PWM Speed Control Double Coil Brushless DC Motor Driver
SILICON TOUCH TECHNOLOGY INC.
9-7F-1 Prosperity Road I Science-Based Industrial Park Hsinchu, Taiwan 300, R.O.C. Tel886-3-5645656 Fax886-3-5645626
SILICON TOUCH TECHNOLOGY INC.
ST1115C/ST1115D
ST1115C/ST1115D PWM Speed Control Double Coil Brushless DC Motor Driver
General Specifications
The ST1115 serial IC is a driver with pulse-width modulated (PWM) speed control for two-phase unipolar DC brushless fan applications. The device is used as an interface between a HALL effect latch and a double coil load. Besides its high-efficiency driving capability, the ST1115 has various functions such as rotation detection (for ST1115C only), tachometer signal output (for ST1115D only), linear fan speed control, exterior PWM control, locked-rotor protection and self-restart. The speed command can be either a PWM signal or simply a voltage reference according to the applications. For the temperature-proportional fan speed control, the voltage command can be generated by an external temperature sensor, typically a thermistor-resistor divider. If the motor rotation is stalled by external force or obstacles, overdrive current (or lock current) may incur coil overheat/burning. To prevent coil overheat/burning, this device incorporates locked-rotor protection circuitry to shut down the drivers. After the motor locking is released, the drivers can be automatically powered up by the internal self-restart circuitry.
Features and Benefits
High-efficiency PWM fan speed control Linear temperature-speed control with minimum external circuitry High output sinking current capability Lock protection and automatic self-restart Tachometer output Directly connectable to a HALL Latch IC Thin, highly reliable package ( SOP8, MSOP8 )
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ST1115C/ST1115D
Pin Assignment
GND FGR CF VT O1 VDD O2 HIN
Pin NO. 1 2 3 4 5 6 7 8
Pin Name GND FGR CF VT HIN O2 VDD O1 Ground
Description
Rotation Detection Output (for ST1115C) Fan Tachometer Output (for ST1115D) Lock Timing Capacitor Input pin for PWM duty control Input pin from Hall Latch IC Output driver 2 Power supply Output driver 1
Absolute Maximum Ratings
Characteristic Supply Voltage Input Voltage Output Current at Lock Output Current at Operating Power Dissipation (SOP8) Power Dissipation (MSOP8) Operating Temperature Range Storage Temperature Range
( TA=25 )
Symbol VDD VIN IOUT IOPR PD PD TA TS Rating 14 VDD+0.4 1000 600 0.68 0.48 -40 ~ 125 -65 ~ 150 Unit V V mA mA W W C C
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ST1115C/ST1115D
Electrical Characteristic
Characteristic Supply Voltage Quiescent Current HIN Input Terminal Input Voltage "H" Input Voltage "L" Input Current "H" Input Current "L" VIH VIL IIH IIL Sym. VDD IDD
( TA = 25 & VDD = 12 V )
Condition Operating No load, All Inputs = 0V or VDD VIN = VDD VIN = 0 V Min. 3 Limit Typ. 12 3 Max. 14 Unit V mA
10 -0.4 -
0.3
12.4 1.5 1 0.5
V V A mA
O1 / O2 Output Terminal ( TJ = 25) Output Voltage High Output Voltage Low VOH VOL IOUT = 250mA 250 mV mV
FG Open-Drain Terminal ( TJ = 25) Output Leakage Current Output Current Output Voltage High ILeak IFG VFGOH VFG =12V VFG = 0.2V 10 10 15 A mA V
VT PWM Speed Control Terminal ( TJ = 25) VT Threshold Voltage VTHL VT Threshold Voltage VTHH Lock Protection and Restart Lock Protection Time Ratio of Protection Time to Restart Time TOFF RLOCK
The capacitor connected to the CF pin is of value CF F .
100% PWM Duty Cycle 50% PWM Duty Cycle
-
3.88 3.18
-
V V
-
2.5*CF 3
-
sec
TOFF / TON
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ST1115C/ST1115D
HIN Input and the Output Driver States
HIN H L O1 OFF ON O2 ON OFF
Internal PWM Duty Cycle v.s. VT Input
Different voltage levels of the VT pin correspond to different internal PWM duty cycles. The relation of VT v.s. Duty Cycle is shown below, which illustrates a linear relation within the range of 3.18~3.88 V (VDD= 12 V). If the linear temperature control is desired, the VT terminal is biased in this linear region through a thermistor-resistor divider. In this way, the fan speed can vary linearly with respect to the temperature variation; the higher temperature results in the faster speed. Additionally, applying the exterior PWM command to the VT terminal can also control the fan speed. Note that the low level and high level of the exterior PWM command must be lower than 3.18 V and higher than 7.7 V (VDD= 12 V), respectively. The exterior PWM is active low.
PWM Duty Ratio v.s. VT voltage
100%
Active Duty (%)
50%
0%
3.18
3.88
7.7
12 Volt
Voltage of VT ( VDD=12 Volt)
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ST1115C/ST1115D
Application Circuits and Designer's Notes
1. Temperature-sensing fan speed control Refer to Figure 1.
POWER
VDD
75 ohm
D1
VDD HALL IC HIN LOCK DETECTION and PROTECTION
R1 VT
FGR
COM
VT CF LOGIC BLOCK
O1 + O2
(1) If the linear temperature control is desired, the VT terminal is connected to a thermistor-resistor divider, as shown in Fig. 1. In this way, the fan speed can vary linearly with respect to the temperature variation; the higher temperature results in the faster speed. (2) Figure 2 illustrates the desired temperature-speed curve. Assume that the resistance of the thermistor is RT1 when the temperature is at T1, and RT2 at T2. Also assume that the voltage V1 applied to the VT pin will result in the fan speed rpm1, and V2 applied to the VT pin yielding rpm2. Note that the relation between the VT voltage and the fan speed depends on the size and the coil impedance of the fan. To obtain the desired temperature-speed curve, the resistance values of R1 and R2 in Fig. 1 can be roughly selected by the following equations.
SP-ST1115CD-A.005
Thermistor R2
CF GND
PWM CONTROL
Figure 1. Fan speed control by the external temperature sensor.
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ST1115C/ST1115D
R2 =
R1 =
V1(V2 - VDD )R T2 + V2(VDD - V1)R T1 VDD (V1 - V2)
(VDD - V1)(R T1 + R2) V1
where VDD denotes the voltage at the VDD pin, see Fig. 1. Normally, VDD is around 10.8 Volt, which may slightly vary with the variation of the driving current.
Fan Speed
rpm2
rpm1 T1 T2
Temperature
Figure 2. Desired Temperature-Speed Curve
(3) The FGR pin provides the rotation detection output for ST1115C and the tachometer output for ST1115D. FGR is an open-drain output with a built-in 100k pullup resistor. An additional resistor can be used to pull up the FGR voltage to the appropriate level, which depends on the voltage level of the monitoring/control system.
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ST1115C/ST1115D
2. Temperature-control Fan Switch Refer to Figure 3.
Analog Power
Digital Power
D1 R6 C2
VSS
R7 VDD RD Hin ST1115C VT O1 RD
R2 R1 R4
R3
Hall IC
VSS
Q1
Q2
CF GND
O2
Thermistor R5
VSS VSS
C1
VSS VSS
Z1
VSS VSS
Z2
Figure 3. Temperature-control Fan Switch (where ST1115C is shown for illustration). (1) Figure 3 shows the temperature-control fan switch circuit, where the fan either stops or rotates at the full speed, depending on some temperature threshold. Figure 4 indicates the graph of the fan speed as a function of the temperature. The temperature threshold is T with the hysteresis T2-T1.
Figure 4.
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ST1115C/ST1115D
3. Fan speed control by the PWM command Refer to Figure 5.
Analog Power
Digital Power
D1 R3 C2 1u Hall IC
VSS
75 VDD
VSS
R4 10K RD
RD Hin ST1115C VT O1
R2
R1 PWM
Q1
CF GND C1 1u
O2
Z1
VSS VSS VSS VSS
Z2
VSS
Figure 5. Fan speed control via the PWM command.
(1) Figure 5 shows the application circuit, where the fan speed is directly controlled by the PWM command. The BJT Q1 together with resistors R1 and R2 constitutes an inverting level shifter, which is responsible for translating the voltage level of the PWM command to the VDD voltage level of the drive IC. In this way, the voltage level of the PWM command can be very low, say, 2 Volt, for example. (2) For this circuit, the PWM command is active high and its frequency range is 200 Hz ~ 40 KHz. If low acoustic noise is desired, the 20 KHz~40 KHz of the PWM frequency range is recommended.
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ST1115C/ST1115D
4.Operating as a pre-driverRefer to Figure 6. (1) When a large fan is used, the driving current may be too large for ST1115 directly driving the fan. In this case, ST1115 may operate as a pre-driver, as illustrated in Fig. 6. Q1 and Q2 are PNP BJT, working as driving switches. The fan speed is controlled via the VT terminal, which can be connected to a thermistor-resistor divider or a PWM generator.
Analog Power
Digital Power
D1 R3 C2
VSS
R4 VDD RD Hin ST1115C R1 Q1 Q2 R2 VT O1 O2 CF GND RD
Hall IC
VSS
VT
C1
VSS VSS VSS
Figure 6. ST1115 operates as a pre-driver.
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ST1115C/ST1115D
5. Lock protection and restart timing (1) If the fan is locked, ST1115 will turn the driver off, avoiding high-current damage of the driver. After a period TOFF of turning off, it will try to restart the fan by turning the driver on for a short time TON. The proportion of TOFF to TON is around 3:1. The absolute values of TOFF and TON depend on the capacitor connected to the CF pin. (2) Assume that the capacitance of the capacitor connected to the CF pin is CF. The lock protection time is roughly 3*CF second. The recommended capacitance CF is 1F for roughly 2.5-sec lock protection and 800-msec lock restart.
6. Power Dissipation v.s. Temperature (1) The power dissipation is affected by various factors, such as the supply voltage, the output current, and loading. It is important to ensure the applications do not exceed the allowable power dissipation of the IC package. The allowable motor driver power dissipation versus temperature is depicted as follows:
Power Dissipation-Temperature
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 0
Power Dissipation ( mW )
SOP8 MS OP 8
Ambient Temperature ( )
25
50
75
100
125
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ST1115C/ST1115D
Package Specifications
SOP8 : ST1115C_TSP1 / ST1115D_TSP1
( 8-pin SOP )
ST1115C XXXXXX*
E
H
C
L
D
7(4X)
SYMBOL
A2 A
Dimensions in Millimeter MIN 1.35 0.10 0.33 0.19 4.80 3.80 5.80 0.40 0 NOM 1.60 1.45 1.27 MAX 1.75 0.25 0.51 0.25 5.00 4.00 6.20 1.27 0.10 8
Dimensions in Inches MIN 0.053 0.004 0.013 0.007 0.189 0.150 0.228 0.016 0 NOM 0.063 0.057 1.27 MAX 0.069 0.010 0.020 0.010 0.197 0.157 0.244 0.050 0.004 8
A A1 A2 B C D E e H L Y
A1 y B e
* The product code "ST1115C"or "ST1115D" will be changed dependent on product and the lot number "XXXXXX" will also be subject to change on the package marking.
MSOP8 : ST1115C_TMS1 / ST1115D _TMS1
(8-pin MSOP )
ST1115C XXXXXX*
E1 E C
L D 12(4X)
Dimensions in Millimeter
A2 A
Dimensions in Inches MIN 0.032 0.000 0.030 0.006 0.005 0.114 0.189 0.114 0.016 0 NOM 0.036 0.034 0.008 0.006 0.118 0.193 0.118 0.026 0.021 MAX 0.042 0.004 0.038 0.012 0.009 0.122 0.197 0.122 0.026 0.004 6
SYMBOL A
MIN 0.81 0.00 0.76 0.15 0.13 2.90 4.80 2.90 0.40 0
NOM 0.92 0.86 0.20 0.15 3.00 4.90 3.00 0.65 0.53
MAX 1.07 0.10 0.97 0.30 0.23 3.10 5.00 3.10 0.66 0.10 6
A1 y b e
A1 A2 b C D E E1
* The product code "ST1115C"or "ST1115D" will be changed dependent on product and the lot number "XXXXXX" will also be subject to change on the package marking.
e L Y
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ST1115C/ST1115D
The products listed herein are designed for ordinary electronic applications, such as electrical appliances, audio-visual equipments, communication devices and so on. Hence, it is advisable that the devices should not be used in medical instruments, surgical implants, aerospace machinery, nuclear power control systems, disaster/crime-prevention equipments and the like. Misusing those products may directly or indirectly endanger human life, or cause injury and property loss. Silicon Touch Technology, Inc. will not take any responsibilities regarding the misusage of the products mentioned above. Anyone who purchases any products described herein with the above-mentioned intention or with such misused applications should accept full responsibility and indemnify. Silicon Touch Technology, Inc. and its distributors and all their officers and employees shall defend jointly and severally against any and all claims and litigation and all damages, cost and expenses associated with such intention and manipulation.
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