User’s Guide User’s Guide 1
EVM IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered by TI to be fit for commercial use.
DYNAMIC WARNINGS AND RESTRICTIONS It is important to operate this EVM within the input voltage range of 0 Vdc to100 Vdc. Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are questions concerning the input range, please contact a TI field representative prior to connecting the input power. Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the EVM.
SLUU172 − October 2003 Evaluation Modules for −48-V Hot Swap Controllers Systems Power Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 The −48-V Hot Swap Controller EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SLUU172 − October 2003 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.
SLUU172 − October 2003 Figure 1. Evaluation Module Top Assembly 2.2 EVM Schematic Diagram and List of Materials The EVM schematic diagram is shown in Figure 2.
J2 −48 V_IN TP8 ON OFF 1 TP2 SW1 1 1 D1 C4 0.1 µF 4 TP3 4 3 2 1 U1 GATE RTN 6 7 8 1 TP4 TP5 TP7 C1 1000 pF −VIN 5 C2 0.01 µF 2 IRAMP FLTTME ISNS EN PG TPS2398DGK TPS2399DGK C3 0.047 µF 3 TP1 R3 12 kΩ 1W Power Good R1 200 kΩ 1/8 W, 1% C5 USER 5 R2 7.32 kΩ 1/8 W, 1% TP11 C9 0.082 µF TP9 C8 USER ON OFF TP12 POWER TP10 ENABLE S2 J1 −48 V_RTN S1 + TP6 R4 20 mΩ 0.
SLUU172 − October 2003 Table 1. List of Materials REFERENCE DESIGNATOR QUANTITY DESCRIPTION MANUF PART NUMBER −002 −001 U1 1 − IC, −48-V Hot Swap Controller, w/Retry Texas Instruments TPS2399DGK U1 − 1 IC, −48-V Hot Swap Controller, Latching Texas Instruments TPS2398DGK TP1−TP4, TP6, TP7, TP9, TP11, TP13, TP15 10 10 Jack Test Point, red Farnell 240−345 TP5, TP8, TP10, TP12, TP14, TP16 6 6 Jack, test point, black Farnell 240−333 S1 1 1 Switch, toggle, SPDT, PC Mnt.
SLUU172 − October 2003 2.3 −48-V Hot Swap EVM Operating Specifications The −48−V hot swap EVM is intended to allow some degree of user reconfiguration. This allows designers to set up the circuit to better represent the characteristics of their target application. Potential modifications include changing the current limit threshold, the inrush limiting, the fault timing, and load characteristics.
SLUU172 − October 2003 3.2 Verifying the EVM Operation The following procedure steps may be used to verify functional operation of the EVM after receipt. 3.2.1 Equipment Setup 1. On the EVM board, place the POWER switch in the OFF position, and verify that the ENABLE switch is in the OFF position. 2. Set the DIP switches 1 through 4 of switch SW1 to the ON position. 3. Turn on the power supply and adjust the output for about 48 V. Verify the supply current limit is set to allow at least 3 A.
SLUU172 − October 2003 3.2.2 Functional Test 1. Turn on the power supply. On the EVM, place the POWER switch in the ON position. Verify the power good LED (D1) is OFF. Verify the DVM reading is 0 ±100 mV. 2. Place the ENABLE switch in the ON position. Verify the green power good LED turns on, and the DVM now displays approximately the input supply voltage level. The scope should have acquired a sweep similar to that shown in Figure 4.
SLUU172 − October 2003 4 Using the Evaluation Module to Evaluate the TPS2398/99 Procedures similar to the steps of Section 3.2.2 for functional test of the EVM can also be used to continue evaluation of the TPS2398 and TPS2399 hot swap controllers. Additional details about the EVM features are provided in this section. The ENABLE switch can be used to enable and disable power to the load (i.e., the VOUT+ and VOUT− terminals), when the POWER switch is in the ON position.
SLUU172 − October 2003 4.3 Changing the Current Limit Threshold During power-up of a plug-in card, the TPS2398 and TPS2399 limit the peak inrush current drawn by the discharged bulk capacitance. The LCA senses load current as the drop across an external sense resistor. Current is regulated by slewing the gate of the pass FET to maintain the voltage drop at an internally set level, nominally 40 mV. Therefore, the peak current level can be established by selecting the appropriate sense resistor value.
SLUU172 − October 2003 To observe the controller response to a load that does not charge up as expected (a shorted or otherwise excessive load), set switches SW1−1, SW1−2, and SW1−3 to the ON position. This greatly reduces the inrush (load charging) current slew rate at turn-on, with a corresponding increase in the amount of time needed to successfully charge the intended load. Increase the supply level to between approximately 60 V and 80 V, and again enable the device.
SLUU172 − October 2003 If the target application requires fault timing other than that provided by the default EVM setup, a new value of timing capacitor can be calculated from equation (3). When selecting from the readily available capacitor values for the result of equation (3), default to a slightly larger, rather than smaller, capacitor. C FLT + ǒ55 t FLTǓ (3) 3.75 where 4.
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