L295 DUAL SWITCH-MODE SOLENOID DRIVER ■ 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 MULTIWATT15 ORDERING NUMBER: L295 trolled by means of a switch-ing technique allowing very efficient operation. 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. 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. The L295 is designed to accept standard microprocessor logic levels at the inputs and can drive 2 solenoids. The output current is completely conBLOCK DIAGRAM C R 9 10 +VSS VOLTAGE REGULATOR THERMAL SHUTDOWN OSCILLATOR 1 +VS 1 H2 DRIVER D3 15 R1 LOGIC CIRCUITS D4 L2 R R FF2 FF2 Q S 14 LOGIC CIRCUITS D2 L1 3 L1 DRIVER 13 4 12 5 11 7 Vin2 October 2003 Q S L2 DRIVER RS2 D1 2 R2 VREF2 +VS H1 DRIVER EN VREF1 8 6 Vin1 D03IN1503 1/7 L295 ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VS Supply voltage 50 V VSS Logic supply voltage 12 V Enable and input voltage 7 V Reference voltage 7 V Peak output current (each channel) - non repetitive (t = 100 µsec) - repetitive (80% on - 20% off; Ton = 10ms) - DC operation 3 2.5 2 A A A Total power dissipation (at Tcase = 75 ″C 25 W - 40 to 150 °C VEN, Vi Vref Io Ptot Tstg, Tj Storage and junction temperature CONNECTION DIAGRAM 15 OUTPUT H ch 2 14 OUTPUT L ch 2 13 CURRENT SENSING 2 12 REFERENCE VOLTAGE 2 11 INPUT 2 10 LOGIC SUPPLY VOLTAGE VSS 9 OSCILLATOR RC NETWORK 8 GROUND 7 ENABLE 6 INPUT 1 5 REFERENCE VOLTAGE 1 4 CURRENT SENSING 1 3 OUTPUT L ch 1 2 OUTPUT H ch 1 1 SUPPLY VOLTAGE VS D03IN1502 TAB CONNECTED TO PIN 8 THERMAL DATA Symbol 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 ELECTRICAL CHARACTERISTCS (Refer to the application circuit, Vss = 5V, Vs = 36V; Tj = 25°C; L = Low; H = High; unless otherwise specified) Symbol VS Supply Voltage VSS Logic Supply Voltage Test Condition Id Quiescent Drain Current (from VSS) VS = 46V; Vi1 = Vi2 = VEN = L Iss Quiescent Drain Current (from VS) VSS = 10V Input Voltage Low High Vi1,Vi2 2/7 Parameter Min. Max. Unit 12 46 V 4.75 10 V 4 mA 46 mA 0.8 7 V V -0.3 2.2 Typ. L295 ELECTRICAL CHARACTERISTCS (continued) Symbol Parameter Test Condition Min. Typ. Unit 0.8 7 V V VEN Enable Input Voltage Low High Ii1,Ii2 Input Current Vi1 = Vi2 = L Vi1 = Vi2 = H -100 10 µA µA Enable Input Current VEN = L VEN = H -100 10 µA µA 2 V -5 µA 25 46 KHz 2 2.1 A/V IEN Vref1, Vref2 Input Reference Voltage Iref1, Iref2 Input Reference Voltage Fosc -0.3 2.2 Max. 0.2 Oscillator Frequency C = 3.9 nF; R = 9.1 KΩ Transconductance (each ch.) Vref = 1V Ip Vref 1.9 Vref1, Vref2 Input Reference Voltage 0.2 2 V Vref1, Vref2 Input Reference Voltage 0.2 2 V Vdrop Total Output Voltage (each channel) (*) 3.6 V 2 V Vsens1, Vsens2 I 2.8 o=2A External sensing resistors voltage drop (*) Vdrop = VCEsat Q1 + VCEsat Q2. APPLICATION CIRCUIT +VS 1 15 D3 +VSS C2 0.1µF 2 R2 R1 L2 L1 D4 D2 C1 0.1µF 14 3 10 9 R3 9.1K 8 13 12 11 7 6 5 RS2 0.5Ω C4 220µF D1 C3 3.9nF 4 RS1 0.5Ω +VREF2 +VIN2 EN +VIN1 +VREF1 D03IN1501 D2, D4 = 2A High speed diodes trr ≤ 200 ns D1, D3 = 1A High speed diodes trr ≤ 200 ns R1 = R2 = 2W 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. 3/7 L295 These inputs are: – EN 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: V –R1t I = -------- 1 – e ------------- R1 L1 where: 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: V ref1 I p 1 = ------------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: VA –R1t VA I = ------- + Ip1 e ------------- – -------R R1 L1 1 where VA = VCEsat Q2 + Vsense + VD2 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: where VB = VS + VD1 + VD2 VB –R1t VB I = ------- + I T 2 e ------------- – -------R1 R1 L1 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 4/7 L295 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: 2.5 I P = -------RS SIGNAL WAVEFORMS Figure 3. With Vref changed by hardware. Figure 1. Load current waveform with pin 9 connected to GND. I Ip I In IP t0 t0 t1 t2 t t1 t2 t3 tn t Vi ⋅ EN t Vi ⋅ EN t VREF t VREF t ON Q1 ON OFF Q1 OFF t t ON Q2 ON OFF Q2 OFF D03IN1506 t t D03IN1504 Figure 2. Load current waveform with external R-C network connected between pin 9 and ground. Figure 4. Switching frequency vs. values of R and C. f (KHz) I D03IN1507 IP fo=25KHz t0 t1 t2 t3 t4 t5 tn t F 2n F F 15 8n 9n 3. 6. t F 1n 2. Vi ⋅ EN C= 10 nF Rmin VREF t 1 ON Q1 OFF 1 10 100 R(KΩ) t ON Q2 OFF D03IN1505 t 5/7 L295 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 0.022 F 0.66 0.75 0.026 0.030 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 0.862 0.874 0.886 0.870 0.886 0.772 H2 L 20.2 0.795 21.9 22.2 22.5 L1 21.7 22.1 22.5 0.854 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 S 1.9 2.6 0.075 S1 1.9 2.6 0.075 0.102 Dia1 3.65 3.85 0.144 0.152 6/7 OUTLINE AND MECHANICAL DATA 0.713 0.114 0.102 Multiwatt15 V L295 Information furnished is believed to be accurate and reliable. However, STMicroelectronics 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 STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners © 2003 STMicroelectronics - All rights reserved STMicroelectronics GROUP OF COMPANIES Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States www.st.com 7/7