Datasheet DC536 Datasheet (Linear Technology)

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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 536

HOT SWAP CONTROLLER WITH MULTIFUNCTION CURRENT CONTROL

DESCRIPTION

LTC4211

Demonstration circuit DC536 is a Hot Swap controller with multifunction current control featuring the LTC4211. The DC536 is configured to operate with up to 7A as populated by the factory. Optional component pads are provided for a higher power pass FET and sense resistor for operation up to 20A.

The DC536 permits evaluating the LTC4211 during turn-on and turn-off transients as well as during steady state conditions.

Design files for this circuit board are available. Call the LTC factory.

, LTC and Hot Swap are registered trademarks of Linear Technology Corpora-

tion.

Table 1. Performance Summary (TA = 25°C)

PARAMETER CONDITION VALUE

Supply Voltage Rated operating limits 2.5V ≤ VCC ≤ 16.5V

Under Voltage Lockout Transition to operating mode 2.13V ≤ V

ON Pin Threshold Voltage, High 1.23V ≤ V

ON Pin Threshold Voltage, Low 1.20V ≤ V

Gate Pull-Up current Charge Pump On, V

ON Pin Signal Low 130µA ≤ I

Fast Gate Pull-Down Current

Current Limit

Supply Voltage Rated operating limits 2.5V ≤ VCC ≤ 16.5V

• Latched and Circuit Breaker Tripped or in UVLO 50mA

Si4410 and 7m

FDB8030L and 2.5m

0.2V 7.5µA ≤ I

GATE

Ω

SENSE Resistor

Ω

SENSE Resistor

5.7A ≤I

16A ≤ I

CC(UVL)

GATE

LIMIT

≤ 2.47V

≤ 1.39V

≤1.26V

≤ 12.5µA

≤ 270µA Normal Gate Pull-Down Current

≤ 8.5A

≤ 24A

2.13V ≤ V

ON Pin Threshold Voltage, High

Gate Pull-Up current

Normal Gate Pull-Down Current ON Pin Signal Low 130µA ≤ I

1.23V ≤ V

1.20V ≤ V

Charge Pump On, V

0.2V 7.5µA ≤ I

GATE

OPERATING PRINCIPLES

The LTC4211 is a low voltage hot swap controller that has a 2.5V to 16.5V operating range and a 17V absolute maximum operating voltage for the Vcc pin. This demo circuit is populated for +5V operation, but it can easily be re-adjusted for any voltage between 2.5V to 16.5V by replacing R3 and R1 (top resistors in the feedback divider and the ON pin signal divider). There are two as-

sembly options for load current. The DC536 as supplied by the factory is populated with an Si4410 MOSFET in an SO-8 package and a 7mΩ current sense resistor providing a minimum 5A load current. The DC536 has provision for an FDB8030L MOSFET in the DD package which when used with a 2.5mΩ sense resistor provides a minimum16A load current.

CC(UVL)

≤1.26V ON Pin Threshold Voltage, Low

CC(UVL)

≤ 12.5µA

GATE

≤ 270µA

GATE

≤ 2.47V Under Voltage Lockout

≤ 1.39V

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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 536

HOT SWAP CONTROLLER WITH MULTIFUNCTION CURRENT CONTROL

QUICK START PROCEDURE

Demonstration circuit 536 is easy to set up to evaluate the performance of the LTC4211. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below:

The DC536 is factory setup to operate in a 5 volt system at current levels up to 5 amps. If the LTC4211 is to be evaluated at a different operating condition, follow 2-6 below, otherwise skip to 7.

If evaluating at a voltage other than 5V, R3 must be adjusted for proper RESET PIN response. Select R3=V

•15K/1.223-15K, where V

MIN

is the mini-

MIN

mum output voltage expected for normal operation.

The ON pin operates as a precision comparator and can accurately provide an adjustable under voltage lockout. The DC536 is initially configured to turn on at 4.15V

. If 3.3V logic will drive this pin, R1 can

MIN

be replaced with a short. If the ON pin will be used to provide under voltage lockout, then select R1 such that R1=V

•10K/1.39-10K, where V

UVLO

the minimum turn on voltage. Refer to the data sheet figure 3 for common configurations

If the DC536 will operate at other than 7Amps max, increase the value of R

SENSE

=0.99•I

/40mV for a

LOAD

1% tolerance current sense resistor.

If the DC536 will be operating above 7Amps, replace Q1 with a suitable DD package MOSFET such as the FDB8030L suitable for up to 20Amps. There is a DD package footprint on the back of the board.

The soft start and power good (RESET release) delay is factory set to 6.2ms. This delay can be adjusted by changing C

refer to the data sheet

TIMER

Table 1 for common values and the SYSTEM TIMING section for more detailed information.

After any necessary component changes have been made, connect a suitable load between VOUT and GND. This may be a passive resistive load or an active electronic load box.

Connect a power supply capable of supplying

1.5•I

between the VIN and GND turrets. The

LOAD

minimum current capability of the supply must accommodate the tolerance of the circuit breaker threshold of ±20%. With the 7mΩ factory installed

sense resistor, the overload circuit breaker will trip at between 5.7A to 8.5Amp (7Amp nominal). Connect the ON/OFF turret to the VIN turret to enable power to the load. A function generator can be used to generate a single event and trigger a scope. The DC536 provides convenient turrets for observing the FAULT, RESET and VOUT signals.

The following experiments can be run. Turn on into a nominal load. Turn on into an overload. Turn on into a short circuit. Turn on into a nominal load and increase the load until the LTC4211 trips off. A digital storage scope provides a convenient means of observing the turn on and overload events. Observe the input or output current using a current probe. A current transformer can be used to observe turn on current transients if a current probe is not available.

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