LT1336 Linear Technology, LT1336 Datasheet - Page 14

• Manufacturer Part Number: LT1336
• Description: Half-Bridge N-Channel Power MOSFET Driver with Boost Regulator
• Manufacturer: Linear Technology

APPLICATIONS
LT1336
most power supplies cannot sink current, this current can
raise the voltage of the high voltage rail. This can be
avoided by placing a discharge resistor between HV sup-
ply and ground to divert the return current to ground as
shown in Figure 5. For a high voltage rail of 40V, a 26k
resistor or smaller should be used, since the top driver will
return about 1.5mA.
For applications where using a discharge resistor is unde-
sirable, use the flyback regulator topology instead of the
boost regulator topology (see Deriving the Floating Supply
with the Flyback Topology).
To drive a DC motor in both directions, two LT1336s can
be used to drive an H-bridge output stage. In this configu-
ration the motor can be made to run clockwise, counter-
clockwise, stop rapidly (“plugging” braking) or free run
(coast) to a stop. A very rapid stop may be achieved by
reversing the current, though this requires more careful
design to stop the motor dead. In practice a closed-loop
control system with tachometric feedback is usually
necessary.
TYPICAL APPLICATIONS
14
SHUTDOWN
0.022 F
4.7k
1 F
510
+
C1
0.1 F
360
2k
** MAGNETICS CORE #55585-A2 30 TURNS 14GA MAGNET WIRE
* SUMIDA RCR-664D-221KC
†
DALE TYPE LVR-3 ULTRONIX RCS01
0.33 F
0.1 F
0.1 F
27k
U
Figure 6. 90% Efficiency, 40V to 5V, 10A, Low Dropout Voltage Mode Switching Regulator
1
2
3
4
5
6
7
8
9
f = 25kHz
LT3526
INFORMATION
4.7k
U
18
17
16
15
14
13
12
11
10
U
1N4148
1N4148
W
+
2.2nF
1 F
1k
5k
+
2N2222
U
1k
2
10 F
R
SENSE
1/4W
1
2
3
4
5
6
7
8
I
SV
INTOP
INBOTTOM
UVOUT
SGND
PGND
BGATEFB
SENSE
+
+
The motor speed in these examples can be controlled by
switching the drivers with pulse width modulated square
waves. This approach is particularly suitable for micro-
computers/DSP control loops.
LT1336
200 H
10 F
L1*
R
2
1/4W
SENSE
TGATEDR
TSOURCE
BGATEDR
TGATEFB
SWITCH
SWGND
BOOST
Figure 5. Driving a Supply Referenced Motor
PV
V
V
I
+
+
SENSE
+
LT1336
16
15
14
13
12
11
10
9
1N4148
D1
1N4148
+
200 H*
IRFZ44
TSOURCE
BGATEDR
TGATEDR
TGATEFB
BGATEFB
SWITCH
BOOST
1 F
PGND
1N4148
IRFZ44
330k
+
V
–
BOOST
IRFZ44
+
+
70 H
L2**
MBR340
D2
1N4148
C
1 F
+
BOOST
2200 F EA
LOW ESR
12V
0.007
40V
HV = 40V MAX
R
S
+
†
*SUMIDA
RCR-664D-221KC
+
1336 F06
5400 F
LOW
ESR
R
24k
DISCHRG
5V
1336 F05