Datasheet LT1336 (Analog Devices) - 15

LT1336
applicaTions inForMaTion
current can raise the voltage of the high voltage rail. This The motor speed in these examples can be controlled by can be avoided by placing a discharge resistor between HV switching the drivers with pulse width modulated square supply and ground to divert the return current to ground waves. This approach is particularly suitable for micro- as shown in Figure 5. For a high voltage rail of 40V, a 26k computers/DSP control loops. resistor or smaller should be used, since the top driver D1 will return about 1.5mA. 1N4148 For applications where using a discharge resistor is un- 200µH* HV = 40V MAX desirable, use the flyback regulator topology instead of + R R DISCHRG SENSE the boost regulator topology (see Deriving the Floating D2 24k 2Ω I 1/4W SENSE SWITCH 1N4148 Supply with the Flyback Topology). + V+ BOOST VBOOST To drive a DC motor in both directions, two LT1336s V+ + TGATEDR 10µF can be used to drive an H-bridge output stage. In this + TGATEFB CBOOST LT1336 1µF configuration the motor can be made to run clockwise, – TSOURCE counterclockwise, stop rapidly (“plugging” braking) or free BGATEDR run (coast) to a stop. A very rapid stop may be achieved BGATEFB *SUMIDA by reversing the current, though this requires more careful PGND RCR-664D-221KC design to stop the motor dead. In practice a closed-loop 1336 F05 control system with tachometric feedback is usual y
Figure 5. Driving a Supply Referenced Motor
necessary.
Typical applicaTions
C1 0.1µF 4.7k 0.1µF + + 12V L1* 1µF 10µF 200µH 1 18 40V 4.7k 360Ω RSENSE + + 2Ω, 1/4W 2200µF EA 2 17 1 16 1N4148 LOW ESR ISENSE SWITCH 0.33µF 2k 1N4148 LT1336 1N4148 3 16 2 15 SV+ SWGND 4 15 3 14 INTOP BOOST 0.022µF + 5 14 1k 4 13 LT3526 1µF INBOTTOM TGATEDR IRFZ44 0.1µF 1N4148 5k 6 13 + 5 12 510Ω UVOUT TGATEFB 1µF 330k L2** R † S 70µH 0.007Ω 7 12 1k 6 11 2N2222 SGND TSOURCE 5V 8 11 7 10 + 5400µF SHUTDOWN PGND PV+ LOW IRFZ44 IRFZ44 MBR340 ESR 9 10 8 9 BGATEFB BGATEDR 27k 2.2nF f = 25kHz * SUMIDA RCR-664D-221KC ** MAGNETICS CORE #55585-A2 30 TURNS 14GA MAGNET WIRE † 1336 F06 DALE TYPE LVR-3 ULTRONIX RCS01
Figure 6. 90% Efficiency, 40V to 5V, 10A, Low Dropout Voltage Mode Switching Regulator
1336fa 15 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Test Circuit Timing Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts