L295 DUAL SWITCH-MODE SOLENOID DRIVER PRELIMINARY DATA HIGH CURRENT CAPABILITY (up to 2.5A per channel) HIGH VOLTAGE OPERATION (up to 46V for power stage) HIGH EFFICIENCY SWITCHMODE OPERATION REGULATED OUTPUT CURRENT (adjustable) FEW EXTERNAL COMPONENTS SEPARATE LOGIC SUPPLY THERMAL PROTECTION DESCRIPTION The L295 is a monolithic integrated circuit in a 15 lead Multiwatt ® package; it incorporates all the functions for direct interfacing between digital circuitry and inductive loads. The L295 is designed to accept standard microprocessor logic levels at the inputs and can drive 2 solenoids. The output current is completely controlled by means of a switch- Multiwatt 15 ORDER CODE : L295 ing technique allowing very efficient operation. Furthermore, it includes an enable input and dual supplies (for interfacing with peripherals running at a higher voltage than the logic). The L295 is particularly suitable for applications such as hammer driving in matrix printers, step motor driving and electromagnet controllers. ABSOLUTE MAXIMUM RATINGS Symbol Vs Vss VEN, Vi Vref Io Parameter Supply voltage Logic supply voltage Enable and input voltage Reference voltage Peak output current (each channel) - non repetitive (t = 100 µsec) - repetitive (80% on - 20% off; Ton = 10 ms) - DC operation Ptot Tstg, Tj Total power dissipation (at Tcase = 75 °C Storage and junction temperature Value 50 12 7 7 Unit V V V V 3 2.5 2 25 A A A W - 40 to 150 °C APPLICATION CIRCUIT March 1993 1/8 L295 CONNECTION DIAGRAM (top view) BLOCK DIAGRAM THERMAL DATA Symbol 2/8 Parameter Value Unit Rth-j-case Thermal resistance junction-case max 3 °C/W Rth-j-amb Thermal resistance junction-ambient max 35 °C/W L295 ELECTRICAL CHARACTERISTICS (Refer to the application circuit, Vss = 5V, Vs = 36V; Tj = 25°C; L = Low; H = High; unless otherwise specified) Symbol Parameter Vs Supply Voltage Vss Logic Supply Voltage Test conditions Min. Typ. Max. Unit 12 46 V 4.75 10 V Id Quiescent drain current (from VSS) VS = 46V; Vi1 = Vi2 = VEN = L 4 mA Iss Quiescent drain current (from VS) VSS = 10 V 46 mA Vi1,,Vi2 VEN Ii1, Ii2 IEN Input Voltage Enable Input Voltage Input Current Enable Input Current Vref1, Vref2 Input Reference Voltage Iref1, Iref2m Input Reference Voltage C = 3.9 nF; Transconductance (each ch.) Vref = 1V Vdrop Total output voltage drop (each channel) (*) Io = 2 A Vsens1 Vsens2 External sensing resistors voltage drop Ip -0.3 0.8 High 2.2 7 Low -0.3 0.8 High 2.2 7 Vi1 = Vi2 = L -100 Vi1 = Vi2 = H 10 VEN = L -100 VEN = H 10 0.2 Oscillation Frequency Fosc Low 1.9 V µA µA 2 V -5 µA 25 R = 9.1 KΩ V KHz 2 2.1 A/V 2.8 3.6 V 2 V Vref (*) Vdrop = VCEsat Q1 + VCEsat Q2. 3/8 L295 APPLICATION CIRCUIT D2, D4 = 2A High speed diodes D1, D3 = 1A High speed diodes ) trr ≤ 200 ns R1 = R2 = 2Ω L1 = L2 = 5 mH FUNCTIONAL DESCRIPTION The L295 incorporates two indipendent driver channals with separate inputs and outputs, each capable of driving an inductive load (see block diagram). The device is controlled by three micriprocessor compatible digital inputs and two analog inputs. These inputs are: chip enable (digital input, active low), enables both channels when in the low state. Vin1, Vin2 channel inputs (digital inputs, active high), enable each channel independently. A channel is actived when both EN and the appropriate channel input are active. Vref1, Vref2 referce voltages (analog inputs), used to program the peak load currents. Peak load current is proportional to Vref . Since the two channels are identical, only channel one will be described. The following description applies also the channel two, replacing FF2 for FF1, Vref for Vref1 etc. When the channel is avtivated by low level on the EN input and a high level on the channel input, Vin2, the output transistors Q1 and Q2 switch on and current flows in the load according to the exponential law: I = where: EN 4/8 V R1 (1 − e − R1 t L1 ) R1 and R2 are the resistance and inductance of the load and V is the voltage available on the load (Vs - Vdrop Vsense). The current increases until the voltage on the external sensing resistor, RS1, reaches the reference voltage, Vref1. This peak current, Ip1, is given by: Ip1 = Vref1 RS1 At this point the comparator output, Vomp1, sete the RS flip-flop, FF1, that turns off the output transistor, Q1. The load current flowing through D2, Q2, RS1, decreases according to the law: I = ( VA R1 + Ip1 ) e − R1 t L1 where VA = VCEsat Q2 + Vsense + VD2 − VA R1 L295 If the oscillator pin (9) is connected to ground the load current falls to zero as shown in fig. 1. At this time t2 the channel 1 is disabled, by taking the inputs Vin1 low and/or EN high, and the output transistor Q2 is turned off. The load current flows through D2 and D1 according to the law: I = ( VB R1 + IT2 ) e − R1 t L1 − VB R1 where VB = VS + VD1 + VD2 IT2 = current value at the time t2. Fig. 2 in shows the current waveform obtained with an RC network connected between pin 9 and ground. From to t1 the current increases as in fig. 1. A difference exists at the time t2 because the current starts to increase again. At this time a pulse is produced by the oscillator circuit that resets the flip.flop, FF1, and switches on the outout transistor, Q1. The current increases until the drop on the sensing resistor RS1 is equal to Vref1 (t3) and the cycle repeats. The switching frequency depends on the value R and C, as shown in fig. 4 and must be chosen in the range 10 to 30 KHz. It is possible with external hardware to change the reference voltage Vref in order to obtain a high peak current Ip and a lower holding current Ih (see fig. 3). The L295 is provided with a thermal protection that switches off all the output transistors when the junction temperature exceeds 150°C. The presence of a hysteresis circuit makes the IC work again aftera fall of the junction temperature of about 20°C. The analog input pins (Vref1 , Vref2) can be left open or connected to Vss; in this case the circuit works with an internal reference voltage of about 2.5V and the peak current in the load is fixed only by the value of Rs: Ip = 2.5 RS SIGNAL WAVEFORMS Figure 1. Load current waveform with pin 9 connected to GND. Figure 2. Load current waveform with external R-C network connected between pin 9 and ground. 5/8 L295 SIGNAL WAVEFORMS (continued) Figure 3. With Vref changed by hardware. 6/8 Figure 4. Switching frequency vs. values of R and C. L295 MULTIWATT15 PACKAGE MECHANICAL DATA mm DIM. MIN. TYP. inch MAX. MIN. TYP. MAX. A 5 0.197 B 2.65 0.104 C 1.6 D 0.063 1 0.039 E 0.49 0.55 0.019 F 0.66 0.75 0.026 0.022 G 1.02 1.27 1.52 0.040 0.050 0.060 G1 17.53 17.78 18.03 0.690 0.700 0.710 H1 19.6 0.030 0.772 H2 20.2 0.795 L 21.9 22.2 22.5 0.862 0.874 0.886 L1 21.7 22.1 22.5 0.854 0.870 0.886 L2 17.65 18.1 0.695 L3 17.25 17.5 17.75 0.679 0.689 0.699 L4 10.3 10.7 10.9 0.406 0.421 0.429 L7 2.65 2.9 0.104 M 4.25 4.55 4.85 0.167 0.179 0.191 M1 4.63 5.08 5.53 0.182 0.200 0.218 0.713 0.114 S 1.9 2.6 0.075 0.102 S1 1.9 2.6 0.075 0.102 Dia1 3.65 3.85 0.144 0.152 7/8 L295 Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement 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 SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. © 1994 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A. 8/8