DC102A Demo Manual

DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
LT1336 Half-Bridge N-Channel
Power MOSFET Driver
with Boost/Flyback Regulator
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DESCRIPTIO
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 highside driver regulator allows PWM operation to 100% duty
cycle without discontinuities. By adding a controller IC and
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PERFORMANCE SUMM ARY
SYMBOL
PARAMETER
VIN
LT1336 Input Voltage Range
some other components in the space provided for
prototyping, this demo board can be turned into a complete 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.
Operating Temperature Range 0°C to 50°C, VIN = 12V unless otherwise noted.
CONDITION
VALUE
10V to 15V
IQ
LT1336 Typical Supply Current
HV
High Voltage Range
INTOP = INBOTTOM = 0V
15mA
RDS(ON)
Power MOSFETs RDS(ON)
VGS = 10V
0.09Ω
ESR
ESR of Bypass Capacitor
100kHz
0.03Ω
IPK
Max Ripple Current
PIN
Max Power Input
fMAX
Max Operating Frequency
0V to 50V (60V Abs Max)
4.5A
(Note 1)
150W
100kHz
Note 1: For applications requiring higher input power, attach heat sinks to all power MOSFETs.
BOARD PHOTOS
Demo Board with a Flyback High-Side Driver Regulator
Demo Board with a Boost High-Side Driver Regulator
1
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
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PACKAGE AND SCHEMATIC DIAGRAMS
TOP VIEW
D2
1N4148
E3
VIN
10V TO 15V
SV
R2,2Ω
1/4W, 5%
+
C1
10µF
25V
R1
24k
1/4W
5%
C11
0.1µF
50V
+
SWGND
BOOST
INTOP
T1*
D1
1N4148
R7
6.2k
1/4W D3
5% 1N4148
C9
1000pF
25V
SW
ISENSE
INBOTTOM
TGATEDR
UVOUT
TGATEFB
SGND
TSOURCE
PGND
PV +
BGATEDR
BGATEFB
E4
UVOUT
1 I
SENSE
2
SV+
3 INTOP
E5
INTOP
E6
INBOTTOM
4
5
6
7
8
N PACKAGE
16-LEAD PDIP
SW 16
15
SWGND
BOOST 14
INBOTTOM
U1
LT1336
UVOUT
TGATEDR
TGATEFB
SGND
TSOURCE
PGND
PV+
BGATEFB
BGATEDR
LT1336CN
E1
HV
0V TO 50V
13
C2
1µF
25V
12
R3
10Ω
1/4W
5%
11
10
R4
10Ω
1/4W
5%
+
Q2
MTP50N06V
Q1
MTP50N06V
C3 TO C8
330µF
63V
×6
E2
OUT
9
D5
1N5819
E7
GND
R5
10Ω
1/4W
5%
R6
10Ω
1/4W
5%
Q3
MTP50N06V
Q4
MTP50N06V
*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
Figure 1. Demonstration Circuit with a Flyback HIgh-Side Driver Regulator
D2
1N4148
L1 REPLACES THE DASHED
COMPONENTS IN FIGURE 1
C1
10µF
25V
+
R2
2Ω
1/4W
5%
E3
VIN
10V TO 15V
E5
INTOP
E6
INBOTTOM
E4
UVOUT
L1*
200µH
1 I
SENSE
2
SV+
3 INTOP
4
R1, 24k
1/4W, 5%
13
INBOTTOM
TGATEDR
U1
LT1336
5
12
UVOUT
TGATEFB
6
7
8
SGND
TSOURCE
PGND
PV+
BGATEFB
D1
1N4148
SW 16
15
SWGND
BOOST 14
BGATEDR
+
C2
1µF
25V
11
10
R4
10Ω
1/4W
5%
Q1
MTP50N06V
R5
10Ω
1/4W
5%
R6, 10Ω
1/4W
5%
Q3
MTP50N06V
BOLD LINES INDICATE HIGH CURRENT PATHS
* SUMIDA RCH-664D-221 KC
Figure 2. Demonstration Circuit with a Boost High-Side Driver Regulator
2
+
Q2
MTP50N06V
C3 TO C8
330µF
63V
×6
E2
OUT
9
D5
1N5819
E7
GND
R3
10Ω
1/4W
5%
E1
HV
0V TO 40V
Q4
MTP50N06V
DM102A • F02
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
PARTS LIST
REFERENCE
DESIGNATOR
PART NUMBER
DESCRIPTION
VENDOR
C1
QUANTITY
1
25SC10M
10µF 25V 20% Electrolytic Capacitor
Sanyo
(619) 661-6835
TELEPHONE
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 START 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 VIN
(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 recommended 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 voltages as high as VIN.
• Connect the load between OUT (E2) and GND (E7).
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OPERATION
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 amplifiers. 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 VIN (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
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DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
U
OPERATION
generator to INTOP (E5) and INBOTTOM (E6). These
inputs to the LT1336 are TTL/CMOS compatible and can
withstand input voltages as high as VIN. 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
VBOOST – VTSOURCE is 10.6V. Unlike bootstrapping techniques 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 capacitor 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
Functional Diagram for the LT1336
V+
ISENSE
+
1
16 SW
–
15 SWGND
14 BOOST
6V
480mV
TRIP = 10.6V
TRIP = 8.7V
V+
2
TOP UV
DETECT
BIAS
13 TGATEDR
–
3k
3
12 TGATEFB
+
INTOP
5V
2.9V
11 T SOURCE
10 PV +
3k
INBOTTOM
4
5V
BOTTOM
UV LOCK
5
SGND
6
PGND
7
BGATEFB
8
–
UVOUT
9
+
2.5V
DC102 FD
4
BGATEDR
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
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OPERATION
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
VIN + 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 snubbing 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 VIN. However, no power
is transferred to VBOOST 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 VIN, the secondary forward biases the rectifier
diode D1 and the transformer’s energy is transferred to
VBOOST. Meanwhile, the primary inductor current goes to
zero and the voltage at ISENSE 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 VIN will be higher,
however, by a factor of VBOOST/VIN.
To reconfigure the demo board’s flyback regulator into a
boost regulator, remove the snubber circuit’s components, 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 VBOOST. 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 VIN is delivered to VBOOST. 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.
5
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
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PC LAYOUT AND FILM
6
Component Side Silkscreen
Component Side
Component Side Pastemask
Component Side Solder Mask
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
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PC LAYOUT AND FILM
Solder Side
Solder Side Soldermask
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
7
DEMO MANUAL DC102
50V N-CHANNEL HALF BRIDGE
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PC FAB DRAWING
4.975
H
B
B
C
C
C
C
C
C
C
C
C
C
C
C
E
D
C
E
D
E
E
E
C C
A
G
E
E
E
E
F
E
E
E E
E
3.975
E E
D
D
C C
D D
C C
D
G
E
D
A
G
C
C
E E
G
E
E E
F
A
A
F
D
D D
D
B
B
E
E
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
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417 ● (408) 432-1900
FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com
H
DM102A • PC FAB DWG
SYMBOL
DIAMETER
NUMBER
OF HOLES
A
0.095
4
B
0.125
4
C
0.028
21
D
0.032
180
E
0.040
24
F
0.205
3
G
0.156
4
H
0.072
2
TOTAL HOLES
242
LT/GP 0197 500 • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 1997
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