Linear LTC7000 Demo Manual
DEMO MANUAL DC2537A
LTC7000
Fast High Voltage Protected
High Side NMOS Static Switch Driver
DESCRIPTION
Demonstration circuit 2537A is a 135V protected, high
side switch featuring the LT C®7000. The demo board is
designed to switch a 5.5A output load from input voltages
from 8V to 135V. The wide input range and low shutdown current (1µA typical) make it suitable for automotive, industrial, medical instrument and telecom applications. This board offers a low 50ns (typical) propagation
delay, fast switching times (<10ns) and 100% duty cycle
operation.
The LTC7000 is a fast high voltage protected high side
N-channel MOSFET driver. An internal charge pump fully
enhances an external N-channel MOSFET switch, allowing
it to remain on indefinitely. Its powerful gate driver can
drive large gate capacitance MOSFETs with very short
transition times, ideal for both high frequency switching and static switch applications. The LTC7000 operates
over a 3.5V to 135V input supply range. When an external
current sense resistor and internal comparator sense that
the switch current has exceeded a preset level, a fault flag
is asserted and the switch is turned off after a period of
time set by an external timing capacitor. After a cooldown
period, the LTC7000 can be configured to automatically
retry or remain off until input is cycled.
The demo board includes input capacitors and output
diode to accommodate input and output supply inductance when switching loads. The switch can be controlled
directly with external signal or using the on-board on/off
switch. A single-shot pulse generator is included for evaluating switching times while limiting output power. Optional
auxiliary VCC input accommodates gate power associated
with high frequency switching. Positions for RC delay net
work to control inrush current are also included.
The LTC7000 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this demo manual
for demo circuit 2537A. Proper board layout is essential
for maximum thermal and electrical performance. See the
data sheet sections for details. The LTC7000 is available
in 16-lead MSOP package and three operating junction
temperature grades (extended and industrial –40°C to
125°C, high temp automotive –40°C to 150°C and a military grade –55°C to 150°C.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2537A
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog
Devices, Inc. All other trademarks are the property of their respective owners.
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PERFORMANCE SUMMARY
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
I
OUT
V
IN
V
CCUV
Input Voltage 135 V
Output Current 5.5 A
Insertion Drop V
Start-Up Voltage V
VCC Undervoltage Lockout VCC Rising
Overcurrent to V
Input to Output Propagation Delay V
Output Rise Time V
Low Turn-On into a 10A Resistive Load 19 µs
OUT
Specifications are at TA = 25°C
– V
IN
INP
100kΩ Load
VCC Falling
Hysteresis
IN
IN
, 5.5A Load, Input to Output Terminals 150 mV
OUT
= 4V
6.5
5.8
= 135V, 50Ω Load, INP = 2.2V to V
= 135V, 50Ω Load, 10% to 90% 6.5 ns
= 13.5V 50 ns
OUT
8.0
7.0
7.0
6.4
0.6
7.5
6.9
dc2537af
1
V
V
V
V
V
DEMO MANUAL DC2537A
QUICK START PROCEDURE
Refer to Figure 1 for proper measurement equipment
setup and follow the procedure below:
NOTE: When measuring the output voltage during switching transitions, care must be taken to avoid a long ground
lead on the oscilloscope probe. Measure the output voltage by touching the probe tip and ground ring directly
across the output capacitor as shown in Figure 2.
1. Place SW1 to OFF position. Move JP1 from the PULSE
(default position) to ON/OFF position (load on continu
ously when SW1 is ON).
2. With input power supply set to zero volts and power
off, connect the input power supply to +VIN and GND.
3. With power off, connect load from +VOUT to GND.
4. Turn on the input power supply and increase the input
voltage slowly to 9V minimum. The input range is up
to 135V but hot-plugging with long leads may result
in input voltages in excess of 135V.
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5. Place SW1 to ON position.
6. Check for the proper output voltage using a voltmeter.
Output voltage should be close to input voltage.
NOTE: If there is no output, temporarily disconnect the
load and cycle SW1 (the ON/OFF switch) or press reset
pushbutton SW2. If output is good, the load may be
set too high.
7. Once the proper output voltage is established, adjust
the load, if desired, to test current limit.
8. Placing SW1 to OFF position, moving JP1 to PULSE
position then placing SW1 in ON position will allow
pulse operation. Pushing SW2 will turn the high side
on for 300µs time.
switch
9. Placing SW1 to OFF position, moving JP1 to INPUT
position connects INPUT terminal to LTC7000 INP pin.
An INPUT pin voltage of 2.2V or more will turn-on the
high side switch.
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Figure 1. Proper Measurement Equipment Setup
dc2537af
QUICK START PROCEDURE
50V/DIV
DEMO MANUAL DC2537A
+ –
V
Figure 2. Measuring Output Voltage During Switching across C9. Note that C9 May Not Be Installed
OUT
C9
GND
TYPICAL PERFORMANCE CHARATERISTICS
Figure 3. Rise Time into 50Ω Load (V
= 135V, CH4 V
IN
INP
5V/DIV, CH3 V
V
OUT
V
INP
5V/DIV
20V/DIV, 10ns/DIV)
OUT
Figure 4. Board Photo
dc2537af
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