Integrated Protection IC On 12V Bus With VT505 Evaluation Kit Manual An Integrated Mosfet, Lossless Current Sensing And Pmbus Interface pass FET, V , and UVLO during normal operation. If GS General Description any fault (other than input or output UVLO) is detected, This evaluation kit (EV kit) serves as a reference for the VT505 latches the pass FET off and reports the fault evaluating Maxims VT505 integrated protection IC on by asserting the FAULT signal low. Restarting the system a 12V bus. The VT505 is a circuit breaker protection IC requires 12V supply cycling, EN/UVLO toggling, or IN with an integrated low resistance MOSFET and loss- PMBus commands. The EV kit consists of an assembled less current sense circuitry featuring PMBus control and and tested printed circuit board implementation of a 12V reporting. The VT505 monitors the current and the voltage power distribution network with circuit-breaker protection of the 12V system power rail and provides multiple levels using the VT505 protection IC. All the VT505 features can of protection. The IC is designed to provide the optimum be verified using this EV kit. More thorough explanations solution for distribution, control, monitoring and protection of topics discussed in this manual can be found in the of the systems 12V power supply. An internal LDO pro- VT505 data sheet. vides the supply voltage for the protection IC. The VT505 monitors the current and the voltage of the 12V system Benefits and Features power rail and provides multiple levels of protection with High Density (6.5mm x 4mm for 60A): Less than 25% fast turn off if a fault is detected. of the Board Area of Conventional Solutions Three methods of overcurrent protection are provided. Monolithic Integration of Power, Control and Programmable moderate OCP level allows surge cur- Monitoring rents for a limited time. User selectable severe OCP - Integrated Power MOSFET with 0.9mW Total level provides a fast disconnect if a current exceeding the Resistance in 12V Power Path (RDSON), severe OCP threshold is detected. An additional, fixed Including Package high shutdown OCP level provides instantaneous discon- - Integrated Lossless, Precise Current Sensing nect to further protect the device. User programmable - Integrated LDO Provides V Supply (1.8V Bias DD Startup OCP is available to protect the device during Supply) soft-start. Enables Advanced System Power Management Maxims patented lossless current sense provides high PMBus/SMBus Telemetry with Extensive Status accuracy current sensing over load and temperature, Monitoring and Reporting improving overall system energy efficiency, and reducing Load Current Indicator (ILOAD) Pin Provides Ana- dissipation. A signal proportional to the load current is log Output Current Reporting with High Accuracy reported through an analog output and extensive report- Programmable Soft-Start for Inrush Current Limiting ing is provided using a PMBus. Increases Power Supply Reliability with IC Output voltage is monitored at all times. If at any time Self-Protection Features the output voltage falls below the programmable output Very Fast Fault Detection and Isolation undervoltage lockout threshold, the PWRGD signal is - Detection and Isolation of Severe Overcurrent in asserted low. If at any time the input voltage falls below Less Than 5s the programmable input undervoltage lockout threshold, - Fail-Safe Overcurrent (Safe-OCP) Detection and the PWRGD signal is asserted low. If the input voltage Isolation in Less Than 250ns exceeds a programmable overvoltage threshold, the Three Levels of Programmable Overcurrent MOSFET is latched off and a fault indicated. During start- Protection up, the PWRGD signal is deasserted low. The VT505 has V to V Short Protection During Startup IN OUT been designed to provide controlled, monotonic startup. Systems and Applications Programmable soft-start is implemented to limit the inrush current during startup. The VT505 performs the follow- Servers, Networking, Storage, Communication Equipment ing check procedures at every startup: pass FET short and AC/DC Power Supplies detection, the soft-start capacitor discharge ROCP resis- 12V Power Distribution and Protection IC: Circuit tor value check and pass FET, V , and UVLO check. GS Breaker/E-Fuse, Hot Swap The VT505 also provides overtemperature protection and Ordering Information appears at end of data sheet. 19-7254 Rev 3 2/17VT505 Evaluation Kit Manual Integrated Protection IC On 12V Bus With An Integrated Mosfet, Lossless Current Sensing And Pmbus Interface System Configuration Table 1. System Configuration PARAMETER COMPONENT/SETTING PARAMETER COMPONENT/SETTING Input UVLO Threshold 10.3V Integrated Protection IC on VT505 12V Bus Bootstrap Capacitor 1x 0.22F Soft-Start Capacitor C (C2) 1x 47nF (0402, 25V) 1x 180F (OS-CON) SS Input Capacitors 1x 10F Soft-Start Time 19ms 1x 2.2F Severe OCP Threshold 130% of Moderate OCP (PMBus) 2 x 330F (OS-CON) 1x 10F Moderate OCP Timeout Output Capacitors 100s 1x 2.2F (PMBus) 1x 0.1F Input OVP Protection (PMBus) 14V (Disabled by default) Startup Delay (PMBus) 0s SMBus Address Programming 1.78k Resistor (R23) Output PWRGD Threshold 11V SMBus Address 40h (PMBus) Input Transient Voltage Self-Test Threshold (PMBus) 9V 1 x 14V, 400W Suppressor Overtemperature Warning/ Disabled / 135C Output Schottky Diode 1 x 30V, 80A Fault Thresholds (PMBus) Input Overpower Warning R (R9 + R10/R11). 1 x 301k OCP Disabled Threshold (PMBus) Moderate OCP Threshold 1 x 137k Programming Resistor 1 x 330k Reporting and Warning 1 Sample Averaging Size (PMBus) Moderate OCP Threshold 68A / 41A R (R13). Current 1 x 4.42k Output Overcurrent Warning ILOAD Disabled Reporting Resistor 0402, 0.1% (PMBus) ILOAD Reporting Range 0 - 61A Input/Output Undervoltage Disabled Warning (PMBus) Pullup resistors Current Hysteresis Disabled (FAULT, PWRGD, SMBUS 5 x 10k (0402) DATA, SMBUS CLK, SMBUS Startup OCP 16A ALERT) Note 1. For Hot Swap operation C should be removed and IN additional C might be required. OUT EN/UVLO Voltage Divider 1 x 20k (R15, R16) 1 x 2.26k EV kit provides additional circuitry for measurements and Additional Components testing: 1 x 180F (OS-CON) + 1 x 10F additional input capacitors to increase input voltage filtering (not PMBus interface for telemetry and programming loaded by default). fast output short to ground 2A, 30V Schottky diode to protect VT505 from on-the-fly moderate OCP threshold change damage in case of high-inductive short on output soft-start capacitor C discharge fail SS (> 400nH). pass FET short protection 100mA LDO to provide 3.3V pullup voltage for PMBus and LEDs. wrong ROCP or SMBUS ID resistor fault detection A transient voltage suppressor to protect VT505 from Additional components like sense/test jumpers and con- damage in case of high inductance input connection. nectors could be loaded on the board. Maxim Integrated 2 www.maximintegrated.com