1
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
LT1336 Half-Bridge N-Channel
Power MOSFET Driver
with Boost/Flyback Regulator
D
U
ESCRIPTIO
This demonstration circuit is an N-channel half-bridge for
general purpose applications. The half-bridge can be driven
with TTL/CMOS level signals into an LT
®
1336, which
drives the N-channel MOSFETs. A self-contained high-
side driver regulator allows PWM operation to 100% duty
cycle without discontinuities. By adding a controller IC and
some other components in the space provided for
prototyping, this demo board can be turned into a com-
plete system solution. The half-bridge consists of four
power MOSFETs, two paralleled topside MOSFETs and
two paralleled bottom side MOSFETs.
, LTC and LT are registered trademarks of Linear Technology Corporation.
PERFORMANCE SUMMARY
UWWW
SYMBOL PARAMETER CONDITION VALUE
V
IN
LT1336 Input Voltage Range 10V to 15V
I
Q
LT1336 Typical Supply Current INTOP = INBOTTOM = 0V 15mA
HV High Voltage Range 0V to 50V (60V Abs Max)
R
DS(ON)
Power MOSFETs R
DS(ON)
V
GS
= 10V 0.09Ω
ESR ESR of Bypass Capacitor 100kHz 0.03Ω
I
PK
Max Ripple Current 4.5A
P
IN
Max Power Input (Note 1) 150W
f
MAX
Max Operating Frequency 100kHz
Operating Temperature Range 0°C to 50°C, VIN = 12V unless otherwise noted.
Note 1: For applications requiring higher input power, attach heat sinks to all power MOSFETs.
Demo Board with a Flyback High-Side Driver Regulator Demo Board with a Boost High-Side Driver Regulator
BOARD PHOTOS
2
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
PACKAGE AND SCHEMA TIC DIAGRAMS
UWW
C3 TO C8
330µF
63V 
× 6
Q2
MTP50N06V
Q4
MTP50N06V
Q3
MTP50N06V
R5
10Ω
1/4W
5%
R3
10Ω
1/4W
5%
R6, 10Ω
1/4W
5%
Q1
MTP50N06V
R4
10Ω
1/4W
5%
C2
1µF
25V
E2
OUT
E1
HV
0V TO 40V
D1
1N4148
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
I
SENSE
SV
+
INTOP
INBOTTOM
UVOUT
SGND
PGND
BGATEFB
SW
SWGND
BOOST
TGATEDR
TGATEFB
TSOURCE
PV
+
BGATEDR
U1
LT1336
BOLD LINES INDICATE HIGH CURRENT PATHS
* SUMIDA RCH-664D-221 KC
DM102A • F02
+
E4
UVOUT
E5
INTOP
E3
V
IN
10V TO 15V
E6
INBOTTOM
E7
GND
R2
2Ω
1/4W
5%
L1*
200µH
R1, 24k
1/4W, 5%
+
+
C1
10µF
25V
D2
1N4148
D5
1N5819
L1 REPLACES THE DASHED 
COMPONENTS IN FIGURE 1
Figure 2. Demonstration Circuit with a Boost High-Side Driver Regulator
C3 TO C8
330µF
63V 
× 6
Q2
MTP50N06V
Q4
MTP50N06V
Q3
MTP50N06V
R5
10Ω
1/4W
5%
R3
10Ω
1/4W
5%
R6
10Ω
1/4W
5%
Q1
MTP50N06V
R4
10Ω
1/4W
5%
C2
1µF
25V
E2
OUT
E1
HV
0V TO 50V
D1
1N4148
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
I
SENSE
SV
+
INTOP
INBOTTOM
UVOUT
SGND
PGND
BGATEFB
SW
SWGND
BOOST
TGATEDR
TGATEFB
TSOURCE
PV
+
BGATEDR
U1
LT1336
*T1 = CTX100-1P
BOLD LINES INDICATE
HIGH CURRENT PATHS
FOR BOOST TOPOLOGY REPLACE COMPONENTS IN DASHED AREA WITH THE INDUCTOR AS SHOWN IN FIGURE 2
DM102A • F01
+
D5
1N5819
T1*
D3
1N4148
R7
6.2k
1/4W
5%
C9
1000pF
25V
D2
1N4148
R2,2Ω
1/4W, 5%
C11
0.1µF
50V
R1
24k
1/4W
5%
C1
10µF
25V
+
E4
UVOUT
E5
INTOP
E6
INBOTTOM
E7
GND
E3
V
IN
10V TO 15V
Figure 1. Demonstration Circuit with a Flyback HIgh-Side Driver Regulator
LT1336CN
TOP VIEW
I
SENSE
SV
+
INTOP
INBOTTOM
UVOUT
SGND
PGND
BGATEFB
SW
SWGND
BOOST
TGATEDR
TGATEFB
TSOURCE
PV
+
BGATEDR
N PACKAGE
16-LEAD PDIP
3
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
PA SLIST
RT
REFERENCE
DESIGNATOR QUANTITY PART NUMBER DESCRIPTION VENDOR TELEPHONE
C1 1 25SC10M 10µF 25V 20% Electrolytic Capacitor Sanyo (619) 661-6835
C2 1 25SC1M 1µF 25V 20% Electrolytic Capacitor Sanyo (619) 661-6835
C3 to C8 6 63MV330CZ 330µF 63V Aluminum Capacitor Sanyo (619) 661-6835
C9 1 FKC02 1000pF 25V 10% Mylar Capacitor WIMA (914) 347-2474
C10 1 25SC10M Option Capacitor Sanyo (619) 661-6835
C11 1 MKS2 0.1µF 63V 5% Mylar Capacitor WIMA (914) 347-2474
D1 to D3 3 1N4148 Diode Philips (800) 774-4547
D5 1 1N5819 Diode Motorola (602) 244-3576
L1 1 RCR-664D-221KC 0.99Ω 0.30A Inductor (Optional) Sumida (847) 956-0666
Q1 to Q4 4 MTP50N06V 50A 60V TO-220 MOSFET Motorola (602) 244-3576
R1 to R7 7 1/4W 5% Resistor Any
T1 1 CTX100-1P Transformer Coiltronics (407) 241-7876
U1 1 LT1336 IC LTC (408) 432-1900
QUICK ST ART GUIDE
Demonstration board 102 is easily set up for evaluation
of the LT1336 IC. Please follow the procedure below for
error-free operation.
• Connect the positive lead of a low power supply to V
IN
(E3) and the negative lead to GND (E7). The voltage
range of this supply must be between 10V – 15V.
• Connect the positive lead of a high power supply to HV
(E1) and the negative lead to GND (E7). The recom-
mended maximum operating voltage is 50V. The
capacitors, the MOSFETs and the IC are rated at 60V
absolute maximum.
• Connect the driving signals into INTOP (E5) and
INBOTTOM (E6). Taking INTOP high and INBOTTOM
low turns the top MOSFETs on and the bottom
MOSFETs off. Taking INTOP low and INBOTTOM high
reverses these states. When both inputs are either
high or low, all the MOSFETs are off. These inputs are
TTL/CMOS compatible and can withstand input volt-
ages as high as V
IN
.
• Connect the load between OUT (E2) and GND (E7).
OPERATION
U
A general purpose half-bridge is implemented using the
LT1336. Figure 1 is the schematic for this demonstration
board. The half-bridge can be used as a building block for
a number of different applications, including synchronous
switching regulators, motor control and class-D amplifi-
ers. By adding the appropriate controller IC in the
prototyping space, a complete system solution can be
created.
This demonstration unit is intended for the evaluation of
the LT1336 half-bridge driver and was not designed for
any other purpose.
To power this demo board, connect a low power 10V to
15V supply to V
IN
(E3) and a high power supply, up to 50V
to HV (E1). To evaluate the LT1336 driving the half-bridge,
connect two complementary signals from a function
4
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
OPERATION
U
generator to INTOP (E5) and INBOTTOM (E6). These
inputs to the LT1336 are TTL/CMOS compatible and can
withstand input voltages as high as V
IN
. Both driver
channels are noninverting. The internal logic of the LT1336
prevents the top MOSFETs and bottom MOSFETs from
turning on simultaneously under any input conditions. For
instance, when both inputs are high both outputs are
actively held low.
The LT1336 incorporates a small switching regulator to
charge the floating high-side driver supply above the high
voltage rail. This regulator can provide enough charge to
the floating supply capacitor to allow the top driver to drive
several power MOSFETs in parallel at 100kHz, its maxi-
mum operating frequency. The regulator voltage across
V
BOOST
– V
TSOURCE
is 10.6V. Unlike bootstrapping tech-
niques with internal charge pumps, the built-in regulator
enables the half-bridge to operate from PWM to DC
without discontinuities.
In conventional half-bridge drivers using bootstrapping
techniques and internal charge pumps, approaching DC
may cause some serious problems. When the duty cycle
approaches 100%, the output pulse width becomes too
narrow for the floating capacitor to recharge. This capaci-
tor is being continuously depleted by the gate charging
currents of the top MOSFETs. The internal charge pump is
too weak to provide the currents needed to replenish the
–
+
–
+
V
+
V
+
I
SENSE
INTOP
INBOTTOM
BOOST
TRIP = 10.6V
TRIP = 8.7V
16 SW
SWGND
TGATEDR
TGATEFB
T SOURCE
PV
+
BGATEDR
DC102 FD
SGND
PGND
BIAS
3k
2
4
5
6
1
3k
TOP UV
DETECT
BOTTOM
UV LOCK
2.9V
2.5V
480mV
5V
5V
6V
UVOUT
–
+
15
14
13
12
11
10
9
BGATEFB 8
3
7
Functional Diagram for the LT1336
5
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
OPERATION
U
floating capacitor. Thus, at a point between 90% and
100% duty cycles, the floating capacitor will be depleted,
causing a discontinuity and potential overdissipation of
the top MOSFETs.
In this demo board the built-in switching regulator of the
LT1336 comes configured as a flyback regulator, as
shown in Figure 1. To configure a flyback regulator, a
resistor, a diode, a small 1:1 turns ratio transformer and a
capacitor are needed. The maximum voltage across the
switch, assuming an ideal transformer, will be about
V
IN
+ 11.3V. Leakage inductance in nonideal transformers
will induce an overvoltage spike at the switch the instant
that it opens. These spikes are clamped using the snub-
bing network D3, C9 and R7. Using the components as
shown in Figure 1, the flyback regulator will run at around
800kHz. To lower the frequency, increase the value of C11;
to raise the frequency, decrease the value of C11.
The flyback regulator works as follows: when the switch is
on, the primary current ramps up as the magnetic field
builds up. The magnetic field in the core induces a voltage
on the secondary winding equal to V
IN
. However, no power
is transferred to V
BOOST
because the rectifier diode D1 is
reverse biased. The energy is stored in the transformer’s
magnetic field. When the primary inductor peak current is
reached, the switch is turned off. Energy is no longer
transferred to the transformer, causing the magnetic field
to collapse. The collapsing magnetic field induces a change
in voltage across the transformer’s windings. During this
transition the Switch pin’s voltage flies to 10.6V plus a
diode above V
IN
, the secondary forward biases the rectifier
diode D1 and the transformer’s energy is transferred to
V
BOOST
. Meanwhile, the primary inductor current goes to
zero and the voltage at I
SENSE
decays to the lower inductor
current threshold with a time constant of (R2)(C11), thus
completing the cycle.
Using the flyback regulator allows the maximum voltage
(50V) to be applied at the high voltage rail, HV. In applica-
tions where the high voltage rail does not exceed 40V, the
boost topology can be used. The advantage, as shown in
Figure 2, is simplicity . Only a resistor, a small inductor, a
diode and a capacitor are needed; there is no need for a
snubber circuit. The current drawn from V
IN
will be higher,
however, by a factor of V
BOOST
/V
IN
.
To reconfigure the demo board’s flyback regulator into a
boost regulator, remove the snubber circuit’s compo-
nents, C9, R7, D3 and the transformer T1. Reconnect
diode D1 and insert the optional inductor as shown in the
Board Photos. Using the components provided with the
demo board (2Ω sense resistor, 200µH inductor and 1µF
capacitor) the boost regulator will run at around 700kHz.
To lower the frequency increase the inductor value; to
increase the frequency decrease the inductor value.
The boost regulator works as follows: when the switch is
on, the inductor current ramps up as the magnetic field
builds up. During this interval energy is being stored in the
inductor and no power is transferred to V
BOOST
. When the
2Ω resistor senses that the peak inductor current has been
reached, the switch is turned off. Energy is no longer
transferred to the inductor, causing the magnetic field to
collapse. The collapsing magnetic field induces a change
in voltage across the inductor. The Switch pin’s voltage
rises until diode D1 starts conducting. As the inductor
current ramps down, the lower inductor current threshold
is reached and the switch is turned on, starting the next
cycle.
Current drawn from V
IN
is delivered to V
BOOST
. Some of
this current (~1.5mA) flows through the topside driver to
E2. This current is typically returned to ground via the
bottom MOSFETs or the output load. If the bottom MOSFETs
are off and the output load is returned to HV, E2 will return
the current to HV through the top MOSFET or the output
load. If the HV supply cannot sink current and no load
drawing greater than 1.5mA is connected to the supply, a
resistor from HV to ground may be needed to prevent
voltage buildup on the HV supply.
6
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
PC LA YOUT AND FILM
UW
Component Side Solder Mask
Component Side Silkscreen Component Side
Component Side Pastemask
7
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PC LA YOUT AND FILM
UW
Solder Side Solder Side Soldermask
8
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
LINEAR TECHNOLOGY CORPORATION 1997
LT/GP 0197 500 • PRINTED IN USA
PC FAB DRA WING
U
3.975
4.975
AAA
A
B
B
B
B
C
C
C
C
C
C
C
C
C
C
C
C
CC CC
CC
C
C
C
D
D
DDDD
DDDD
DD
EE
EE E
EE
E
EEE EEE
EE
EE
EEEE
F
F
F
G G
G G
H
H
SYMBOL
A
B
C
D
E
F
G
H
DIAMETER
0.095
0.125
0.028
0.032
0.040
0.205
0.156
0.072
NUMBER
OF HOLES
4
4
21
180
24
3
4
2
242
TOTAL HOLES
NOTES:
1.MATERIAL: FR4 OR EQUIVALENT EPOXY, 2 OZ COPPER CLAD
 THICKNESS 0.062 ±0.006 TOTAL OF 2 LAYERS
2.FINISH:  ALL PLATED HOLES 0.001 MIN/0.0015 MAX COPPER
 PLATE ELECTRODEPOSITED TIN-LEAD COMPOSTION
 BEFORE REFLOW, SOLDER MASK OVER BARE COPPER
 (SMOBC)
3.SOLDER MASK: BOTH SIDES USING GREEN PC-401 OR EQUIVALENT
4.SILKSCREEN: USING WHITE NONCONDUCTIVE EPOXY INK
5.ALL DIMENSIONS ARE IN INCHES
DM102A • PC FAB DWG
E
E
Linear Technology Cor poration
1 630 McCarthy Blvd., Milpitas, CA 95035-7 41 7
●
(408) 432-1900
FAX: (408) 434-0507
●
TELEX: 499-3977
●
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