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SLUU172 − October 2003

5

 Evaluation Modules for −48-V Hot Swap Controllers

1.2

Description

The TPS2398 and TPS2399 simple −48-V hot swap controllers  are integrated solutions
optimized for use in nominal −48-V systems. They are used in conjunction with an external
N-channel MOSFET and sense resistor to enable hot swap, the insertion and removal of plug-in
cards or modules in powered systems. Both devices feature inrush current slew rate and peak
magnitude limiting, which are easily programmed by the sense resistor value, and a single
external capacitor. They facilitate implementation of platform control of the electrical connection
or isolation of the protected load, and provide single-line load fault reporting. An on-chip timer,
also set by a single capacitor, provides filtering against nuisance breaker trips. These features
are all incorporated into a tiny 8-pin MSOP package.

The TPS2398 latches off in response to current faults. The TPS2399 periodically retries the
load, to test for the continued existence of a fault.

2

The −48-V Hot Swap Controller EVM

2.1

Module Description

The −48-V hot swap EVM contains all the components needed to implement a complete telecom
hot swap interface. In addition, it contains some additional components and PCB patterns to
facilitate evaluation of the device.

Banana jacks are provided for connection of the user’s power supply. On the switched side of
the hot swap circuit, jacks are also provided for connection of the user’s electronic or resistive
load, if desired. The board also contains two through-hole patterns for the installation of
large-value aluminum electrolytic capacitors. This capacitance is used to simulate the input bulk
capacitance present at a plug-in’s power inputs. The EVM is supplied from the factory with a
100-

µ

F capacitor installed in one of the locations. The second pattern, connected in parallel with

the first, can be used to increase or otherwise modify the amount of load capacitance.

From the input power jacks, power is applied to the hot swap circuit via a toggle switch
connected in-line with the high-side of the power bus. Bounce of the switch contacts helps the
user observe the response of the devices under power-up conditions resembling those of an
actual application. An on-board slide switch is also provided to independently toggle the status
of the device enable input (EN pin).

With the TPS2398 and TPS2399, both inrush slew rate limiting and a fault time-out period are
externally programmable using capacitors. On the EVM, several options are provided for slew
rate limiting, for quick comparison of the effect of capacitor value on this function. The capacitors
can be quickly switched in and out of the circuit via the DIP switch. Fault timing programming is
set up in a similar manner; some amount of capacitance is hard-wired into the circuit, with the
option of switching in additional capacitance.

Test points are provided throughout the circuit for easy voltage monitoring via oscilloscope or
voltmeter. The test point connections are listed in Table 4.

A pictorial of the −48−V hot swap EVM is shown in Figure 1.

Summary of Contents for TPS2398EBM

Page 1: ...User s Guide 1 User s Guide...

Page 2: ...handling or use of the goods Please be aware that the products received may not be regulatory compliant or agency certified FCC UL CE etc Due to the open construction of the product it is the user s...

Page 3: ...rtainty as to the load specification please contact a TI field representative During normal operation some circuit components may have case temperatures greater than 50 C The EVM is designed to operat...

Page 4: ...The TPS2398 and TPS2399 are negative voltage hot swap controllers intended for use in systems needing to hot swap telecom distribution level voltages They integrate inrush current control peak current...

Page 5: ...tion of the user s electronic or resistive load if desired The board also contains two through hole patterns for the installation of large value aluminum electrolytic capacitors This capacitance is us...

Page 6: ...U172 October 2003 6 Evaluation Modules for 48 V Hot Swap Controllers Figure 1 Evaluation Module Top Assembly 2 2 EVM Schematic Diagram and List of Materials The EVM schematic diagram is shown in Figur...

Page 7: ...TP1 D1 C8 USER 1 TP2 OFF ON ENABLE TP12 TP10 J2 48 V_IN TP8 S2 TP11 TP9 S1 OFF ON J1 48 V_RTN TP5 POWER 1 C6 100 F 100 V C7 100 F 100 V R5 20 k 1 W R4 20 m 0 5 W C2 0 01 F C3 0 047 F C4 0 1 F C9 0 082...

Page 8: ...2 0 5W 1 Vishay Dale WSL 2010 020 1 R5 R6 2 2 Resistor 20 k 1W 5 Venkel CR2512 1W203J Q1 1 1 XSTR MOSFET N channel V BR 100V Int l Rectifier IRF530S J1 J2 J3 J4 4 4 Jack banana non insulated PC mount...

Page 9: ...and negative out of the specified terminal As supplied from the factory the 48 V hot swap EVM is configured for operation under the following target conditions shown in Table 3 Table 3 Recommended Op...

Page 10: ...t 3 A Turn off the power supply 4 Connect the EVM and test equipment as shown in Figure 3 5 On the oscilloscope set the channel amplifiers to the following scales CH1 20 V div CH2 2 V div CH3 5 V div...

Page 11: ...ut supply voltage level The scope should have acquired a sweep similar to that shown in Figure 4 The brief fault timing ramp which is shown in Figure 4 FLTTIME trace may or may not be present dependin...

Page 12: ...erence node TP9 48V_RTN The high side of input power to the EVM When used in conjunction with a lab supply this connects to the TP11 48V_RTN The high side of input power to the EVM When used in conjun...

Page 13: ...m resistor is the closest approximate standard value that is readily available A smaller value resistor is also acceptable but carries a corresponding increase in the maximum current limit 4 4 Changi...

Page 14: ...maximum slew rate in amperes second 4 5 Fault Timing with the TPS2398 TPS2399 Whenever the hot swap controller is limiting current to the load an on chip timer is monitoring this operation against an...

Page 15: ...VIN with a maximum specification value of 36 V This setting is targeted at general telecom applications However it is possible to raise the minimum start up threshold and potentially tighten the tole...

Page 16: ...ute a license from TI to use such products or services or a warranty or endorsement thereof Use of such information may require a license from a third party under the patents or other intellectual pro...

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