Download PDFDual switch-mode solenoid driver
Document overview
- Manufacturer or author: STMICROELECTRONICS
- PDF pages: 7
Technical content
■ 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 cir- cuitry and inductive loads. The L295 is designed to accept standard micro- processor logic levels at the inputs and can drive 2 solenoids. The output current is completely con- trolled by means of a switch-ing technique allow- ing 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. MULTIWATT15 ORDERING NUMBER: L295 DUAL SWITCH-MODE SOLENOID DRIVER BLOCK DIAGRAM DRIVER DRIVER THERMAL SHUTDOWN VOLTAGE REGULATOR Vin2 EN Vin1 OSCILLATOR DRIVER DRIVER LOGIC CIRCUITS LOGIC CIRCUITSQ 1 176 Q SS RR FF2 FF2 R S2 VREF2 VREF1 C R +VS +VS +VSS D03IN1503 Obsolete Product(s) - Obsolete Product(s)
ELECTRICAL CHARACTERISTCS (Refer to the application circuit, Vss = 5V, Vs = 36V; Tj = 25°C; L = Low; H = High; unless otherwise specified) Symbol Parameter Value Unit VS Supply voltage 50 V VSS Logic supply voltage 12 V VEN , Vi Enable and input voltage 7 V Vref Reference voltage 7 V Io Peak output current (each channel) - non repetitive (t = 100 µsec) - repetitive (80% on - 20% off; Ton = 10ms) - DC operation 2.5 A A A Ptot Total power dissipation (at Tcase = 75 ″C2 5 W Tstg, Tj Storage and junction temperature - 40 to 150 °C 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 Symbol Parameter Test Condition Min. Typ. Max. Unit VS Supply Voltage 12 46 V VSS Logic Supply Voltage 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 = 10V 46 mA Vi1,Vi2 Input Voltage Low High -0.3 2.2 0.8 V V INPUT 2 LOGIC SUPPLY VOLTAGE V SS OSCILLATOR RC NETWORK GROUND ENABLE INPUT 1 REFERENCE VOLTAGE 1 CURRENT SENSING 1 OUTPUT L ch 1 OUTPUT H ch 1 SUPPLY VOLTAGE V S TAB CONNECTED TO PIN 8
12 OUTPUT H ch 2
Obsolete Product(s) - Obsolete Product(s)
(*) Vdrop = VCEsat Q1 + VCEsat Q2. APPLICATION CIRCUIT 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. VEN Enable Input Voltage Low High -0.3 2.2 0.8 V V Ii1,Ii2 Input Current V i1 = Vi2 = L Vi1 = Vi2 = H -100 µA µA IEN Enable Input Current V EN = L VEN = H -100 µA µA Vref1, Vref2 Input Reference Voltage 0.2 2 V Iref1, Iref2 Input Reference Voltage -5 µA Fosc Oscillator Frequency C = 3.9 nF; R = 9.1 K Ω 25 46 KHz Ip Transconductance (each ch.) V ref = 1V 1.9 2 2.1 A/V Vref Vref1, Vref2 Input Reference Voltage 0.2 2 V Vref1, Vref2 Input Reference Voltage 0.2 2 V Vdrop Total Output Voltage (each channel) (*) Io = 2 A 2.8 3.6 V Vsens1, Vsens2 External sensing resistors voltage drop Symbol Parameter Test Condition Min. Typ. Max. Unit 9.1K R S2 0.5W 13 12 11 314 D2D4 0.1mF C3 3.9nF +V SS +V S +V REF2 0.1mF 220mF R S1 0.5W +V REF1+V IN2 EN +V IN1 D03IN1501 ELECTRICAL CHARACTERISTCS (continued) Obsolete Product(s) - Obsolete Product(s)
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: 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 volt- age, Vref1. This peak current, Ip1, is given by: 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: 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 tran- sistor Q2 is turned off. The load current flows through D2 and D1 according to the law: 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 V ref1 (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 I V = Ip1 V ref1 R S1 I VA R 1 e R1t– VA I VB R 1 e R1t– VB Obsolete Product(s) - Obsolete Product(s)
DIM. mm inch A 5 0.197 B 2.65 0.104 C 1.6 0.063 D 1 0.039 E 0.49 0.55 0.019 0.022 F 0.66 0.75 0.026 0.030 H1 19.6 0.772 H2 20.2 0.795 L2 17.65 18.1 0.695 0.713 L7 2.65 2.9 0.104 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 OUTLINE AND MECHANICAL DATA Obsolete Product(s) - Obsolete Product(s)
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 L295 Obsolete Product(s) - Obsolete Product(s)