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.
SLUU150 – February 2003 Evaluation Modules for Simple –48-V Hot Swap Controllers Systems Power Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 The Simple –48-V Hot Swap Controller EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SLUU150 – February 2003 1.2 Description The TPS2390 and TPS2391 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.
SLUU150 – February 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.
S1 OFF TP9 TP11 TP13 TP15 POWER ON R1 200 kΩ 1/8 W, 1% R3 12 kΩ 1W + U1 TPS2390DGK TPS2391DGK TP1 RED D1 TP2 1 FAULT + C6 100 µF 100 V RTN 1 C7 100 µF 100 V 8 R5 20 kΩ 1W VOUT+ R6 20 kΩ 1W TP14 TP16 J4 VOUT– TP7 OFF S2 1 ENABLE C8 USER ON R4 7.32 kΩ 1/8 W, 1% 2 EN GATE 7 3 FLTTME ISNS 6 Q1 SUB85N10 TP5 1 4 IRAMP –VIN 5 TP3 TP6 R4 20 mΩ 0.5 W TP4 TP8 SW1 5 J2 –48 V_IN 4 3 2 1 1 TP12 C9 0.082 µF C5 USER C4 0.1 µF 1 C3 0.047 µF C2 0.
SLUU150 – February 2003 Table 1.
SLUU150 – February 2003 2.3 Simple –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.
SLUU150 – February 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.
SLUU150 – February 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 red LED is OFF. Verify the DVM reading is 0 ±100 mV. 2. Place the ENABLE switch in the ON position. Verify the red LED remains off, 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.
SLUU150 – February 2003 4 Using the Evaluation Module to Evaluate the TPS2390/1 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 TPS2390 and TPS2391 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.
SLUU150 – February 2003 4.3 Changing the Current Limit Threshold During power-up of a plug-in card, the TPS2390 and TPS2391 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.
SLUU150 – February 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.
SLUU150 – February 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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