Datasheet LTM4639 (Analog Devices) - 10

LTM4639
DECOUPLING REQUIREMENTS TA = 25°C. Use Figure 1 configuration. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
CIN External Input Capacitor Requirement IOUT = 20A, 4× 22µF Ceramic X7R Capacitors 88 µF (VIN = 2.375V to 7V, VOUT = 1.5V), (See Table 5) CPWR ≥ 4.5V COUT External Output Capacitor Requirement IOUT = 20A (See Table 5) 400 µF (VIN = 2.375V to 7V, VOUT = 1.5V), CPWR ≥ 4.5V
OPERATION Power Module Description
Pulling the RUN pin below 1.1V forces the regulator The LTM4639 is a low input voltage,high performance into a shutdown state. The TRACK/SS pin is used for single output standalone nonisolated switching mode DC/ programming the output voltage ramp and voltage tracking DC power supply. It can provide a 20A output with few during start-up. See the Application Information section. external input and output capacitors. This module provides The LTM4639 is internally compensated to be stable over precisely regulated output voltages programmable via all operating conditions with COMPA tied to COMPB. Table external resistors from 0.6VDC to 5.5VDC over a 2.375V 5 provides a guideline for input and output capacitances to 7V input range. The typical application schematic is for several operating conditions. LTpowerCAD™ is available shown in Figure 22. for transient and stability analysis. Custom compensation The LTM4639 has an integrated constant-frequency current can be used with the COMPA pin using the LTpowerCAD mode regulator, power MOSFETs, 0.3µH inductor, and and an external compensation network. The VFB pin is other supporting discrete components. The switching used to program the output voltage with a single external frequency range is from 250kHz to 770kHz, and the typical resistor to ground. operating frequency is shown in Table 5 for each VOUT. For A remote sense amplifier is provided for accurately sensing switching noise-sensitive applications, it can be externally output voltages ≤3.3V at the load point. synchronized from 250kHz to 800kHz, subject to minimum Multiphase operation can be easily employed with the on-time limitations. A single resistor is used to program synchronization inputs using an external clock source. the frequency. See the Applications Information section. See application examples. With current mode control and internal feedback loop High efficiency at light loads can be accomplished with compensation, the LTM4639 module has sufficient selectable Burst Mode operation using the MODE_PLLIN stability margins and good transient performance with pin. These light load features will accommodate battery a wide range of output capacitors, even with all ceramic operation. Efficiency graphs are provided for light load output capacitors. operation in the Typical Performance Characteristics Current mode control provides cycle-by-cycle fast current section. limit in an overcurrent condition. An internal overvoltage A TEMP+ and TEMP– pin is provided to allow the internal monitor protects the output voltage in the event of an device temperature to be monitored using an onboard overvoltage >10%. The top MOSFET is turned off and the diode connected PNP transistor. This diode connected bottom MOSFET is turned on until the output is cleared. PNP transistor can be used with TEMP monitor devices Overtemperature protection will turn off the regulator’s like the LTC2990, LTC2997, LTC2974 and LTC2978. RUN pin at ~130°C to 137°C. See Applications Information. 4639f 10 For more information www.linear.com/LTM4639