QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 628A
SINGLE CHANNEL 5V HOT SWAP CONTROLLER
LTC4210
DESCRIPTION
Demonstration circuit 628A is a single channel 5V hot
swap controller featuring the LTC4210.
The LTC
®
4210 is a 6-pin SOT-23 Hot Swap
TM
con-
troller that allows a board to be safely inserted and
removed from a live back plane. An internal high side
switch driver controls the GATE of an external N-
channel MOSFET with a supply voltage ranging from
2.7V to 16.5V. The LTC4210 provides the initial tim-
ing cycle and allows the GATE to be ramped up at an
adjustable rate.
Table 1. Performance Summary (T
A
= 25°C)
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
Output Voltage V
OUT
Maximum Output Current
On/Off Control
(
Connection Sense
Turret)
(Limited by Transorb Z1)
V
OUT
= V
IN
-I
LOAD
×(R
SENSE
+R
FET
)
I
LIMIT<
(V
CB
/R
SENSE
);
Remember to consider tolerances (44mV≤V
CB
≤56mV)
Logic High Voltage-On
V
ONHYST
CONDITION
VALUE
2.7V
12V
=V
IN
-I
LOAD
×(0.022Ω)
6A
2.6V
160mV
The LTC4210 features a fast current limit loop provid-
ing active current limiting together with a circuit
breaker timer. The signal at the ON pin turns the chip
on and off and is also used for the reset function.
Design files for this circuit board are available. Call
the LTC factory.
Hot Swap is a trademark of Linear Technology Corporation
OPERATING PRINCIPLES
The LTC4210 combines Hot Swap
TM
inrush current
limiting with an electronic circuit breaker function.
The LTC4210 uses a single capacitor, C
TIMER
to set
multiple timing cycles for the initial power up time,
the circuit breaker hold-off time and automatic retry
duty cycle time. (The LTC4210-1 version provides
automatic retry while the LTC4210-2 version provides
latch-off after fault timeout.)
QUICK START PROCEDURE
circuit 628A is easy to set up to
evaluate the performance of the LTC4210. Refer to
Figure 1. for proper measurement equipment setup
and follow the procedure below:
NOTE:
Demonstration
1.
With power off, connect the input power supply to
V
IN
and GND and a load between V
OUT
and GND.
The load resistance should be
>Vin/6A
or pull less
than 6A.
Turn on the power at the input.
2.
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 628A
SINGLE CHANNEL 5V HOT SWAP CONTROLLER
specifically designed for Hot
Swap have a special pin configuration that uses ex-
tra long pins to first connect the GND and power
signal, then normal length pins for the rest of the
signals and a special short pin for the Connection
Sense signal. This pin configuration prevents turn-
ing on the power to the Hot Swapped board before
the connector is completely engaged.
4.
NOTE:
Connectors
NOTE:
Make
sure that the input voltage does not ex-
ceed 12V or the transient suppressor Z1 will begin
to conduct. The transient suppressor Z1 protects
the input from the turn off voltage spike resulting
from interrupting the high currents flowing through
the lead inductance of the back plane or leads from
the power source.
3.
Connect the
Connection Sense
turret to V
IN
to en-
able the LTC4210. Monitor the output voltage turn
on time waveform or inrush current if a current
probe is available.
there is no output, temporarily disconnect
the load to make sure that the load is not set too
high.
NOTE:
If
Once the proper output voltages are established,
increase the load above 6A and observe the circuit
breaker function. Disconnect the Connection Sense
turret from V
IN
, connect a large (100uF) capacitor
across V
OUT
and GND then connect the Connection
Sense turret to V
IN
and monitor V
OUT
. Observe the
current limiting action during turn on.
Figure 1. Proper Measurement Equipment Setup
2
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