UCC2915 UCC3915 15V Programmable Hot Swap Power Manager FEATURES DESCRIPTION • Integrated 0.15 Ohm Power MOSFET The UCC3915 Programmable Hot Swap Power Manager provides complete power management, hot swap capability, and circuit breaker functions. The only external component required to operate the device, other than power supply bypassing, is the fault timing capacitor, CT. All control and housekeeping functions are integrated, and externally programmable. These include the fault current level, maximum output sourcing current, maximum fault time, and startup delay. In the event of a constant fault, the Internal fixed 2% duty cycle ratio limits average output power. • 7V to 15V Operation • Digital Programmable Current Limit from 0A to 3A • 100 A ICC when Disabled • Programmable ON Time The internal 4 bit DAC allows programming of the fault level current from 0 to 3A with 0.25A resolution. The IMAX control pin sets the maximum sourcing current to 1A above the trip level or to a full 4A of output current for fast output capacitor charging. • Programmable Start Delay • Fixed 2% Duty Cycle • Thermal Shutdown When the output current is below the fault level, the output MOSFET is switched ON with a nominal ON resistance of 0.15 . When the output current exceeds the fault level, but is less than the maximum sourcing level, the output remains switched ON, but the fault timer starts, charging CT. Once CT charges to a preset threshold, the switch is turned OFF, and remains OFF for 50 times the programmed fault time. When the output current reaches the maximum sourcing level, the MOSFET transitions from a switch to a constant current source. • Fault Output Indicator • Maximum Output Current can be set to 1A above the Programmed Fault Level or to a full 4A • Power SOIC and TSSOP, Low Thermal Resistance Packaging BLOCK DIAGRAM 2 IMAX 10 VIN 3 VOUT MAX CURRENT LEVEL 4A 30mV + CHARGE PUMP H = 4A REVERSE VOLTAGE COMPARATOR CURRENT SENSE POWER FET * H = OPEN LINEAR CURRENT AMPLIFIER 1A ABOVE FAULT OVER CURRENT COMPARATOR CURRENT FAULT LEVEL 0–3 AMPS ON TIME CONTROL 14 VOUT 2% DUTY CYCLE 15 0–3A THERMAL SHUTDOWN 0.25 RES INTERNAL BIAS 6 7 8 9 5 B3 B2 B1 B0 GND 4 BIT DAC 4 13 12 HEAT SINK GND PINS Note: Pin numbers refer to DIL-16 and SOIC-16 packages. SLUS198A - FEBRUARY 2000 11 16 CT FAULT 1.5V + – 1 SHTDWN * BODY DIODE UDG-99174 UCC2915 UCC3915 (continued) ABSOLUTE MAXIMUM RATINGS VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +15.5 Volts VOUT VIN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.3V FAULT Sink Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA FAULT Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 to 8V Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . Self Limiting TTL Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 to VIN Storage Temperature . . . . . . . . . . . . . . . . . . . 65 C to +150 C Junction Temperature . . . . . . . . . . . . . . . . . . . 55 C to +150 C Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300 C DESCRIPTION (cont.) The UCC3915 can be put into sleep mode, drawing only 100 A of supply current. Other features include an open drain Fault Output Indicator, Thermal Shutdown, Under- Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. CONNECTION DIAGRAMS DIL-16, SOIC-16 (Top View) N, DP Package PWP-24 (Top View) TSSOP Package SHTDWN 1 24 FAULT VIN 2 23 VOUT VIN 3 22 VOUT VOUT N/C 4 21 N/C GND* 5 20 GND* GND* 6 19 GND* GND* 7 18 GND* GND* 8 17 GND* EGND* 9 16 N/C B3 10 15 CT B2 11 14 IMAX B1 12 13 B0 SHTDWN 1 16 FAULT VIN 2 15 VOUT VIN 3 14 GND* 4 13 GND* EGND* 5 12 GND* B3 6 11 CT B2 7 10 IMAX B1 8 9 B0 *Pin 5 serves as lowest impedance to the electrical ground; Pins 4, 12, and 13 serve as heat sink/ground. These pins should be connected to large etch areas to help dissipate heat. For N Package, pins 4, 12, and 13 are N/C. *Pin 9 serves as lowest impedance to the electrical ground; other GND pins serve as heat sink/ground. These pins should be connected to large etch areas to help dissipate heat. ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = 40°C to +85°C for the UCC2915 and 0°C to 70°C for the UCC3915, VIN = 12V, IMAX = 0.4V, SHTDWN = 2.4V, TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Supply Section Voltage Input Range 7.0 Supply Current Sleep Mode Current SHTDWN = 0.2V, No load Output Leakage SHTDWN = 0.2V 15.0 V 1.0 2.0 mA 100 150 A 20 A Output Section Voltage Drop IOUT = 1A (10V to 12V) 0.15 0.3 V IOUT = 2A (10V to 12V) 0.3 0.6 V IOUT = 3A (10V to 12V) 0.45 0.9 V 2 UCC2915 UCC3915 ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = 40°C to +85°C for the UCC2915 and 0°C to 70°C for the UCC3915, VIN = 12V, IMAX = 0.4V, SHTDWN = 2.4V, TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Output Section (cont.) Voltage Drop (cont). IOUT = 1A, VIN = 7V and 15V 0.2 0.4 V IOUT = 2A, VIN = 7V and 15V 0.4 0.8 V IOUT = 3A, VIN = 7V, 12V Max. 0.6 1.2 V Initial Startup Time Note 2 100 s Short Circuit Response Note 2 100 ns Thermal Shutdown Note 2 165 °C Thermal Hysteresis Note 2 10 °C DAC Section Trip Current Code = 0000-0011 (Device Off) Code = 0100 0.07 0.25 0.45 A Code = 0101 0.32 0.50 0.70 A Code = 0110 0.50 0.75 0.98 A Code = 0111 0.75 1.00 1.3 A Code = 1000 1.0 1.25 1.6 A Code = 1001 1.25 1.50 1.85 A Code = 1010 1.5 1.75 2.15 A Code = 1011 1.70 2.00 2.4 A Code = 1100 1.90 2.25 2.7 A Code = 1101 2.1 2.50 2.95 A Code = 1110 2.30 2.75 3.25 A Code = 1111 2.50 3.0 3.50 A 0.35 1.0 1.65 A 3.0 4.0 5.2 A Max Output Current Over Trip (Current Source Mode) Code = 0100 to 1111, IMAX = 0V Max Output Current (Current Source Mode) Code = 0100 to 1111, IMAX = 2.4V Fault Output Section CT Charge Current VCT = 1.0V 83 –62 47 A CT Discharge Current VCT = 1.0V 0.8 1.2 1.8 A Output Duty Cycle VOUT = 0V 1.0 1.9 3.3 % CT Fault Threshold 1.2 1.5 1.7 V CT Reset Threshold 0.4 0.5 0.6 V 1.5 1.9 Shutdown Section Shutdown Threshold 1.1 Shutdown Hysteresis 150 Input Current 100 V mV 500 nA Open Drain Output Section High Level Output Current FAULT = 5V Low Level Output Voltage IOUT = 5mA 0.2 250 A 0.8 V TTL Input DC Characteristics Section TTL Input Voltage High 2.0 V TTL Input Voltage Low TTL Input High Current VIH = 2.4V TTL Input Low Current VIL = 0.4V 3 Note 1: All voltages are with respect to GND. Current is positive into and negative out of the specified terminal. Note 2: Guaranteed by design. Not 100% tested in production. 3 0.8 V 10 A 1 A UCC2915 UCC3915 PIN DESCRIPTIONS SB0 - B3: These pins provide digital input to the DAC, which sets the fault current threshold. They can be used to provide a digital soft-start and adaptive current limiting. SHTDWN: When this pin is brought to a logic low, the IC is put into a sleep mode drawing typically less than 100 A of ICC.The input threshold is hysteretic, allowing the user to program a startup delay with an external RC circuit. CT: A capacitor connected to ground sets the maximum fault time. The maximum fault time must be more than the time required to charge the external capacitance in one cycle. The maximum fault time is defined as TFAULT = 3 16.1 10 CT. Once the fault time is reached the output 3 CT, will shutdown for a time given by TSD = 833 10 this equates to a 1.9% duty cycle. VIN: Input voltage to the UCC3915. The recommended voltage range is 7 to 15 volts. Both VIN pins should be connected together and connected to power source. VOUT: Output voltage from the UCC3915. Both VOUT pins should be connected together and connected to the load. When switched the output voltage will be approxiIOUT). VOUT must not exceed VIN mately VIN - (0.15 by greater than 0.3V. FAULT: Open drain output, which pulls low upon any fault or interrupt condition, Fault, or Thermal Shutdown. IMAX: When this pin is set to a logic low, the maximum sourcing current will always be 1A above the programmed fault level. When set to a logic high, the maximum sourcing current will be a constant 4A for applications which require fast charging of load capacitance. APPLICATIONS INFORMATION 4 13 HEAT SINK GND PINS VIN 2 +5V 12 VIN CIN R1 5 GND VOUT 3 D1 VOUT 14 15 RL COUT UCC3915 S6 LED SHTDWN 16 FAULT RSD VIN 1 CSD 11 CT CT B0 B1 B2 B3 IMAX 9 8 7 6 10 VIN S1 S2 S3 S4 S5 DIP SWITCH UDG-99175 Figure 1. Evaluation circuit. • Reducing the power distribution inductance (e.g., twist the positive (+) and negative (–) leads of the power supply feeding VIN, locate the power supply close to the UCC3915 or use a PCB ground plane). Protecting The UCC3915 From Voltage Transients The parasitic inductance associated with the power distribution can cause a voltage spike at VIN if the load current is suddenly interrupted by the UCC3915. It is important to limit the peak of this spike to less than 15V to prevent damage to the UCC3915. This voltage spike can be minimized by: • Decoupling VIN with a capacitor, CIN (refer to Fig. 1), located close to the VIN pin. This capacitor is typically less than 1 F to limit the inrush current. • Clamping the voltage at VIN below 15V with a Zener diode, D1(refer to Fig. 1), located close to the VIN pin. 4 UCC2915 UCC3915 APPLICATION INFORMATION (cont.) UDG-94138 16 .1 • 10 3 • CT COUT (max) ≈ (IMAX − ILOAD ) • VOUT Estimating Maximum Load Capacitance For hot swap applications, the rate at which the total output capacitance can be charged depends on the maximum output current available and the nature of the load. For a constant-current, current-limited application, the output will come up if the load asks for less than the maximum available short-circuit current. Where VOUT is the output voltage. For a resistive load of value RI, the value of COUT(max) can be estimated from: To guarantee recovery of a duty-cycle from a shortcircuited load condition, there is a maximum total output capacitance which can be charged for a given unit ON time (Fault time). The design value of ON or Fault time can be adjusted by changing the timing capacitor CT. COUT (max) For worst-case constant-current load of value just less than the trip limit; COUT(max) can be estimated from: 16 .1 • 10 3 • CT ≈ 1 R n • L VOUT 1 − I MAX • R L Figure 2. Load current, timing capacitor voltage, and output voltage of the UCC3915 under fault conditions. SAFETY RECOMMENDATIONS Although the UCC3915 is designed to provide system protection for all fault conditions, all integrated circuits can ultimately fail short. For this reason, if the UCC3915 is intended for use in safety critical applications where UL or some other safety rating is required, a redundant safety device such as a fuse should be placed in series with the device. The UCC3915 will prevent the fuse from blowing for virtually all fault conditions, increasing system reliability and reducing maintenance cost, in addition to providing the hot swap benefits of the device. UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. 603-424-2410 • FAX 603-424-3460 5