DC628A - Demo Manual

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 SwapTM controller 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 Nchannel MOSFET with a supply voltage ranging from
2.7V to 16.5V. The LTC4210 provides the initial timing cycle and allows the GATE to be ramped up at an
adjustable rate.
The LTC4210 features a fast current limit loop providing 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
Table 1. Performance Summary (TA = 25°C)
PARAMETER
CONDITION
VALUE
Minimum Input Voltage
2.7V
Maximum Input Voltage
(Limited by Transorb Z1)
12V
Output Voltage VOUT
VOUT = VIN-ILOAD×(RSENSE+RFET)
=VIN-ILOAD×(0.022Ω)
Maximum Output Current
ILIMIT< (VCB/RSENSE);
Remember to consider tolerances (44mV≤VCB≤56mV)
6A
On/Off Control
Logic High Voltage-On
2.6V
(Connection Sense Turret)
VONHYST
160mV
OPERATING PRINCIPLES
The LTC4210 combines Hot SwapTM inrush current
limiting with an electronic circuit breaker function.
The LTC4210 uses a single capacitor, CTIMER 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
NOTE: Demonstration
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:
1.
With power off, connect the input power supply to
VIN and GND and a load between VOUT and GND.
The load resistance should be >Vin/6A or pull less
than 6A.
2.
Turn on the power at the input.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 628A
SINGLE CHANNEL 5V HOT SWAP CONTROLLER
NOTE: Make
sure that the input voltage does not exceed 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 VIN to enable the LTC4210. Monitor the output voltage turn
on time waveform or inrush current if a current
probe is available.
NOTE: If
there is no output, temporarily disconnect
the load to make sure that the load is not set too
high.
NOTE: Connectors specifically designed for Hot
Swap have a special pin configuration that uses extra 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 turning on the power to the Hot Swapped board before
the connector is completely engaged.
4.
Once the proper output voltages are established,
increase the load above 6A and observe the circuit
breaker function. Disconnect the Connection Sense
turret from VIN, connect a large (100uF) capacitor
across VOUT and GND then connect the Connection
Sense turret to VIN and monitor VOUT. Observe the
current limiting action during turn on.
Figure 1. Proper Measurement Equipment Setup
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 628A
SINGLE CHANNEL 5V HOT SWAP CONTROLLER
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