DEMO CIRCUIT 1704A LTC4280 QUICK START GUIDE LTC4280 2 Hot Swap Controller with I C Compatible Monitoring DESCRIPTION Demonstration circuit DC1704A4A is a 12V rail circuit insertion of up to 12 gauge wires for in-situ testing. An using the LTC4280, Hot Swap Controller with I2C Com- I2C port designed to interface with DC590A allows con- patible Monitoring. trol of DC1704A with LTC s QuickEval software. DC1704A permits evaluating the LTC4280 during a turn Included on a board is an input clamp, input and output on and turn off transients as well as during steady state voltage dividers for UV, OV, and PWRGD comparators, and fault conditions. Design files for this circuit board LEDs to indicate the presence of various voltages and are available. Call the LTC factory. turret terminals for critical signals to facilitate evaluation L, LTC, LT are registered trademarks of Linear Technology Corporation. Hot Swap is trade- in a working system. Input and output connections are mark of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products. made by 93 mil turrets, which if removed, accommodate PERFORMANCE SUMMARY Specifications are at TA = 25C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Input Supply Range 2.9 15. V DD V Input Supply Overvoltage Threshold 15 15.6 16.5 V OV(VDD) V Input Supply Undervoltage Lockout V Rising 2.75 2.84 2.89 V DD(UVL) DD V Input Supply Undervoltage Lockout Hysteresis 75 100 125 mV DD(HYST) INTV Internal Regulator Voltage 2.9 3.1 3.4 V CC INTV INTV Undervoltage Lockout INTV Rising 2.55 2.64 2.79 V CC(UVL) CC CC INTV INTV Undervoltage Lockout Hysteresis 20 55 75 mV CC(HYST) CC V Circuit Breaker Threshold (V -V ) 22.5 25 27.5 mV SENSE(TH) DD SENSE V Current Limit Voltage V =1.3 22.5 26 29.5 mV SENSE DD V =0 7 10 13.5 DD V External N-Channel Gate Drive(V -V V =2.9 to 15V 4.7 5.9 6.5 V GATE GATE SOURCE) DD I External N-Channel Gate Pull-Up Current Gate On, V =0V to 15V 15 20 30 A GATE(UP) GATE I External N-Channel Gate Pulldown Current Gate Off, V =15V 0.8 1.0 1.6 mA GATE(DN)SLOW GATE I Pulldown Current From GATE to SOURCE DuringOC/UVL V -V =100mV, V =4V 300 450 700 mA GATE(DN)FAST DD SENSE GS V On pin Threshold V Rising 1.21 1.235 1.26 V ON(TH) ON V EN Input Threshold V Rising 1.215 1.235 1.255 V EN(TH) EN V OV pin Threshold Voltage V Rising 1.215 1.235 1.255 V OV(TH) OV V UV pin Threshold Voltage V Rising 1.215 1.235 1.255 V UV(TH) UV V Foldback Pin Power Good Threshold V Rising 1.215 1.235 1.255 V FB FB RES AD Converter Resolution 8 Bits UVLO Undervoltage Lockout V Rising, 0C < T < 85C 2.5 V IN A V Rising 2.6 IN V Falling 1.6 IN 1 LTC4280 OPERATING PRINCIPLES The LTC4280 is a low voltage hot swap controller that tor, providing a minimum of 5.4A load current. The cur- has a 2.9V to 15V operating range and a 24V absolute rent limit and circuit breaker thresholds can be adjusted maximum operating voltage for the VDD pin. This demo by changing the sense resistor, RS. To enable demon- circuit is populated for +12V operation, but it can easily stration of higher current applications up to 100A, provi- be readjusted for any voltage between 2.9V and 15V by sions have been made to replace RS with up to three 1W, replacing R1, R2 and R7 (top resistors in the UV and OV 2512 size sense resistors in parallel connection and re- dividers and the FB divider). The DC1704A as supplied place Q1 MOSFET with one in the D2Pack or PowerSO- by the factory is populated with a Si4864DP MOSFET in 10 packages. an SO-8 package and a 4m ,1/2W current sense resis- QUICK START PROCEDURE Demonstration circuit DC1704A4A is easy to set up to tions, Q1 may be replaced with a MOSFET in a SSOT-6 evaluate the performance of the LTC4280. Refer to the package using the alternate pad on the back of the board. Figure 1 for proper measurement equipment setup and 4 The TIMER SELECT jumper can be used to choose follow the procedure below: a startup timer period between the time defined the 1. The DC1704A is a factory setup to operate in a 12 external timer capacitor, CT, or 100ms (built in inter- volt rail with current level up to 5 A. If the LTC4280 is nal startup time). CT is stuffed with a 0.82uF capaci- to be evaluated at different operating conditions, fol- tor at the factory, which provides a 10.1ms2.8ms low 2-3 below, otherwise skip to 4. startup time. To customize the startup time, select CT=T /12.3(ms/uF). START 2. If evaluating at a voltage other than 12V, the follow- ing Demo board component must be adjusted: 5. The LTC4280 does not require an RC network on the GATE pin for compensation. However, an RC network - R1 and R2 for proper UV and OV PIN response, may be used to limit the rate at which the GATE rises - R7 for proper foldback configuration and power-good to provide an inrush current below the internal current detection. limit. Pads for R6 and CG on the back of the board are available for this purpose. R6 and CG may be Select R2=V /V 13.7K*1.235/1.205-13.7K, and MAX MIN stuffed with a 15k resistor, and CG=C * LOAD R1= V *(13.7K+R2)/1.235-13.7-R2, where V and MIN MIN 20uA/I for this purpose. INRUSH V are the minimum and maximum output voltages MAX for which power is determined to be good. 6. The ADIN pin may be used as an input to take volt- age for 8 bit measurement. Jumper ADIN SELECT Select R7= V 3.01K.7K-3.01K. MIN selects between measuring the input voltage or meas- 3. If the DC1704A should operate at other than 5A max, uring the voltage on the ADIN turret. The input volt- change the value of R =0.9922.5mV/I SENSE LOAD(MAX) age is measured through a resistor divider, which de- for a 1% tolerance current sense resistor. faults to a 15.4V full scale range to match the range of the SOURCE pin measurement. To change the full If the DC1704A should operate above 10Amps, replace scale of the input measurement, select Q1 with a suitable MOSFET. There are pads for D2Pack R11=V *12.4k/1.23-12.4k. The ADIN turret sig- and PowerSO-10 packages. The SO-8 pad on the front of RANGE nal is also measured through a voltage divider, but the the board includes an extra area for better heat-sinking bottom resistor is not stuffed at the factory, defaulting this package requires. Alternately, for low power applica- 2