DATASHEET ISL6446 FN7944 Rev 2.00 Dual (180Out-of-Phase) PWM and Linear Controller October 12, 2015 The ISL6446 is a high-performance, triple output controller Features that provides a single high-frequency power solution primarily 4.5V to 5.5V or 5.5V to 24V input voltage range for broadband, DSL and networking applications. This device integrates complete control, monitoring and protection Three programmable power output voltages functions for two synchronous buck PWM controllers and one - Two PWM controllers with out-of-phase operation linear controller. Input voltage ripple and total RMS input - Voltage-mode PWM control current is substantially reduced by synchronized 180 - One linear controller out-of-phase operation of the two PWMs. The two PWM buck converters provide simple voltage mode Programmable switching frequency from 100kHz to 2.5MHz control. The output voltage of the converters can be precisely Fast transient response regulated to as low as 0.6V, with a maximum tolerance of - High-bandwidth error amplifier 1.5% over-temperature and line variations. Programmable switching frequency down to 100kHz provides optimized low Extensive circuit protection functions cost solution for ATX power supplies. Its also able to operate - Undervoltage and over-temperature up to 2.5MHz to deliver compact solutions. The linear - Overvoltage with latch-off mode controller provides a low-current output. - Programmable overcurrent limit with latch-off mode Each PWM controller has soft-start and independent enable - Lossless current sensing (no sense resistor needed) functions combined on a single pin. A capacitor from SS/EN to ground sets the soft-start time pulling SS/EN pin below 1V Externally adjustable soft-start time disables the controller. Both outputs can soft-start into a - Independent enable control prebiased load. - Voltage tracking capability The ISL6446 incorporates robust protection features. An - Able to soft-start into a prebiased load adjustable overcurrent protection circuit monitors the output PGOOD output with delay current by sensing the voltage drop across the upper MOSFET r . Latch-off mode overcurrent operation protects the DS(ON) Applications DC/DC converters from damage under overload and short-circuit conditions. A PGOOD signal is issued when ATX power supplies soft-start is complete and PWM outputs are within 10% of DSP, ASIC and FPGA point of load regulation their regulated values and the linear regulator output is higher Industrial and security networking applications than 75% of its nominal value. Thermal shutdown circuitry turns the device off if the IC temperature exceeds +150C. VCC VIN C 100 VCC R OCSET1 VIN1 = VIN Feedback VCC VIN C 98 OCSET1 COMP1 and OCSET1 C BOOT1 VOUT1 Compensation BOOT1 FB1 Q 1 C 96 Network IN1 UGATE1 R 1 VOUT1 PHASE1 94 L 1 Feedback LGATE1 V = 5V C OUT COMP2 OUT1 and Q 2 92 VOUT2 Compensation FB2 R OCSET2 Network ISL6446 V = 3.3V VIN2 = VIN OUT 90 R 2 C OCSET2 OCSET2 C BOOT2 BOOT2 88 Q 3 C IN2 UGATE2 86 VOUT2 PHASE2 L 2 LGATE2 C OUT2 84 PGOOD Q 4 RT 82 SS1/EN1 LCDR SS2/EN2 80 LCFB 0 5 10 15 20 25 SGND PGND LOAD CURRENT (A) FIGURE 1. TYPICAL APPLICATION FIGURE 2. EFFICIENCY vs LOAD CURRENT (OBTAINED FROM ISL6446EVAL1Z) FN7944 Rev 2.00 Page 1 of 19 October 12, 2015 EFFICIENCY (%) ISL6446 Pin Configuration ISL6446 (24 LD QSOP) TOP VIEW OCSET1 24 VIN 1 SS1/EN1 2 23 BOOT1 COMP1 3 22 UGATE1 FB1 4 21 PHASE1 RT 5 20 LGATE1 SGND 6 19 VCC LCDR 7 18 PGND LCFB 17 LGATE2 8 FB2 9 16 PHASE2 COMP2 10 15 UGATE2 SS2/EN2 11 14 BOOT2 OCSET2 12 13 PGOOD Pin Descriptions SYMBOL PIN DESCRIPTION BOOT2, 1 14, 23 These pins power are the upper MOSFET drivers of each PWM converter. The anode of each internal bootstrap diode is connected to the VCC pin. The cathode of the bootstrap diode is connected to this pin, which should also connect to the bootstrap capacitor. UGATE2, 1 15, 22 These pins provide the gate drive for upper MOSFETs, bootstrapped from the VCC pin. PHASE2, 1 16, 21 These are the junction points of the upper MOSFET sources, the output filter inductor and lower MOSFET drains. Connect these pins accordingly to the respective converter. LGATE2, 1 17, 20 These are the outputs of the lower N-Channel MOSFET drivers, sourced from the VCC pin. PGND 18 This pin provides the power ground connection for the lower gate drivers. This pin should be connected to the source of the lower MOSFET for PWM1 and PWM2 and the negative terminals of the external input capacitors. FB1, 2 4, 9 These pins are connected to the feedback resistor divider and provide the voltage feedback signals for the respective controller. They set the output voltage of the converter. In addition, the PGOOD circuit and OVP circuit use these inputs to monitor the output voltage status. COMP1, 2 3, 10 These pins are the error amplifier outputs for the respective PWM. They are used, along with the FB pins, as the compensation point for the PWM error amplifier. PGOOD 13 This is an open drain logic output used to indicate the status of the output voltages. This pin is pulled low when either of the two PWM outputs is not within 10% of the respective nominal voltage or when the linear output drops below 75% of its nominal voltage. To maintain the PGOOD function if the linear output is not used, connect LCFB to VCC. SGND 6 This is the signal ground, common to both controllers, and must be routed separately from the high current grounds (PGND). All voltage levels are measured with respect to this pin. VIN 24 This pin powers the controllers with an internal linear regulator (if VIN > 5.5V) and must be closely decoupled to ground using a ceramic capacitor as close to the VIN pin as possible. The VIN is the input voltage applied to the upper FET of both converters. TABLE 1. INPUT SUPPLY CONFIGURATION INPUT PIN CONFIGURATION 5.5V to 24V Connect the input supply to the VIN pin. The VCC pin will provide a 5V output from the internal voltage regulator. 5V 10% Connect the input supply to the VCC pin. VCC 19 This pin supplies the bias for the regulators, powers the low-side gate drivers and external boot circuitry for high-side gate drivers. The IC may be powered directly from a single 5V (10%) supply at this pin when used as a 5V supply input, this pin must be externally connected to VIN. When VIN > 5.5, VCC is the output of the internal 5V linear regulator output. The VCC pin must always be decoupled to power ground with a minimum of 1F ceramic capacitor, placed very close to the pin. FN7944 Rev 2.00 Page 2 of 19 October 12, 2015