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L295
DUAL SWITCH-MODE SOLENOID DRIVER
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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 trolled by means of a switch-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.
MULTIWATT15 ORDERING NUMBER: L295
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s
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DESCRIPTION The L295 is a monolithic integrated circuit in a 15 -lead Multiwatt(R) 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 conBLOCK DIAGRAM
C
R
9 +VSS +VS 10 VOLTAGE REGULATOR THERMAL SHUTDOWN
OSCILLATOR 1 +VS
1 H2 DRIVER D3 R2 D4 L2 14 L2 DRIVER RS2 13 12 11 Vin2 7 EN 6 Vin1
D03IN1503
H1 DRIVER 2 R1 LOGIC CIRCUITS Q S R FF2 R FF2 S L1 DRIVER 4 5 8 VREF1 Q LOGIC CIRCUITS L1 3 D2 D1
15
VREF2
October 2003
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ABSOLUTE MAXIMUM RATINGS
Symbol VS VSS VEN, Vi Vref Io Supply voltage Logic supply voltage Enable and input voltage Reference voltage Peak output current (each channel) - non repetitive (t = 100 sec) - repetitive (80% on - 20% off; Ton = 10ms) - DC operation Total power dissipation (at Tcase = 75 C Storage and junction temperature Parameter Value 50 12 7 7 3 2.5 2 25 - 40 to 150 Unit V V V V A A A W C
Ptot Tstg, Tj
CONNECTION DIAGRAM
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 OUTPUT H ch 2 OUTPUT L ch 2 CURRENT SENSING 2 REFERENCE VOLTAGE 2 INPUT 2 LOGIC SUPPLY VOLTAGE VSS OSCILLATOR RC NETWORK GROUND ENABLE INPUT 1 REFERENCE VOLTAGE 1 CURRENT SENSING 1 OUTPUT L ch 1 OUTPUT H ch 1 SUPPLY VOLTAGE VS
D03IN1502
TAB CONNECTED TO PIN 8
THERMAL DATA
Symbol Rth-j-case Rth-j-amb Parameter Value max 3 max 35 Unit
Thermal resistance junction-case Thermal resistance junction-ambient
C/W C/W
ELECTRICAL CHARACTERISTCS (Refer to the application circuit, Vss = 5V, Vs = 36V; Tj = 25C; L = Low; H = High; unless otherwise specified)
Symbol VS VSS Id Iss Vi1,Vi2 Parameter Supply Voltage Logic Supply Voltage Quiescent Drain Current (from VSS) Quiescent Drain Current (from VS) Input Voltage VS = 46V; Vi1 = Vi2 = VEN = L VSS = 10V Low High -0.3 2.2 Test Condition Min. 12 4.75 Typ. Max. 46 10 4 46 0.8 7 Unit V V mA mA V V
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L295
ELECTRICAL CHARACTERISTCS (continued)
Symbol VEN Ii1,Ii2 IEN Vref1, Vref2 Iref1, Iref2 Fosc Ip Vref Vref1, Vref2 Vref1, Vref2 Vdrop Vsens1, Vsens2 Transconductance (each ch.) Input Reference Voltage Input Reference Voltage Total Output Voltage (each channel) (*) External sensing resistors voltage drop
I
Parameter Enable Input Voltage Input Current Enable Input Current Input Reference Voltage Input Reference Voltage Oscillator Frequency Low High
Test Condition
Min. -0.3 2.2
Typ.
Max. 0.8 7 -100 10 -100 10
Unit V V A A A A V A KHz A/V V V V V
Vi1 = Vi2 = L Vi1 = Vi2 = H VEN = L VEN = H 0.2
2 -5
C = 3.9 nF; R = 9.1 K Vref = 1V 1.9 0.2 0.2
o=2A
25 2
46 2.1 2 2
2.8
3.6 2
(*) Vdrop = VCEsat Q1 + VCEsat Q2.
APPLICATION CIRCUIT
+VS
15 R2 D3 D4 L2 14 +VSS C1 0.1F 10 8 13 RS2 0.5 +VREF2 +VIN2 12 11
1
2 R1 D2 L1 3 9 R3 9.1K
C2 0.1F
C4 220F
D1
C3 3.9nF
7
6
5
4 RS1 0.5
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.
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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
I p 1 = -----------RS1
ref1
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 ------------ - ------R1 R1 L1

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:
VB -R1t VB I = ------ + I T 2 e ------------ - ------R1 R1 L1

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 150C. The presence of a hysteresis circuit makes the IC work again aftera fall of
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L295
the junction temperature of about 20C. 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 1. Load current waveform with pin 9 connected to GND.
I IP
Figure 3. With Vref changed by hardware.
I Ip In
t0
t1
t2 t3
tn
t
t0
t1
t2
t
Vi EN t
Vi EN t
VREF t
VREF t
ON
ON Q1 OFF t
Q1 OFF t
ON
ON Q2 OFF
D03IN1504
Q2 OFF
t
D03IN1506
t
Figure 2. Load current waveform with external R-C network connected between pin 9 and ground.
I IP
Figure 4. Switching frequency vs. values of R and C.
f (KHz)
D03IN1507
fo=25KHz
t0
t1
t2 t3 t4 t5
tn
t
10
Vi EN t
15 nF
2. 2n F
3. 9n F
C= F 1n
6. 8n F
VREF t
Rmin
ON Q1 OFF t
1
1
10
100
R(K)
ON Q2 OFF
D03IN1505
t
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L295
DIM. MIN. A B C D E F G G1 H1 H2 L L1 L2 L3 L4 L7 M M1 S S1 Dia1 21.9 21.7 17.65 17.25 10.3 2.65 4.25 4.63 1.9 1.9 3.65 0.49 0.66 1.02 17.53 19.6
mm TYP. MAX. 5 2.65 1.6 1 0.55 0.75 1.27 17.78 1.52 18.03 20.2 22.2 22.1 17.5 10.7 4.55 5.08 22.5 22.5 18.1 17.75 10.9 2.9 4.85 5.53 2.6 2.6 3.85 0.862 0.854 0.695 0.679 0.406 0.104 0.167 0.182 0.075 0.075 0.144 0.019 0.026 0.040 0.690 0.772 MIN.
inch TYP. MAX. 0.197 0.104 0.063 0.039 0.022 0.030 0.050 0.700 0.060 0.710 0.795 0.874 0.870 0.689 0.421 0.179 0.200 0.886 0.886 0.713 0.699 0.429 0.114 0.191 0.218 0.102 0.102 0.152
OUTLINE AND MECHANICAL DATA
Multiwatt15 V
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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 (c) 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
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