UltraBK™ 4A DC–DC Converter Module Limitation of Input Voltage Slew rate When starting the module with ramping Input Voltage up, the slew rate of the ramping should be managed for the proper operation. If Input Voltage ramping up is too steep, it would cause charge injection to the internal nodes via parasitic. The maximum slew rate of the Input Voltage ramp up when booting the module with Input Voltage is specified on the table 4 "Electronic Characteristics". Similarly, if the VIN slew late is too low compare with VOUT slew rate, it could prevent expected start-up behavior. To avoid hitting the maximum duty cycle operation, the VIN slew rate should satisfy the equation of (eq.1). As a reference, estimated value of the slew rate and start-up time for each output voltage is written in the follow table. VINSR_L is minimum of input voltage start-up slew rate. VINSR [V/ms] ≧ 0.2 × 𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉[𝑉𝑉] − 0.1 (eq.1) CALCULATION EXAMPLEOUTPUTVOLTAGE(V)VINSR_L(V/ms)VIN RISE TIME(ms)(0V to 12V) 1.8 0.26 46.2 1.2 0.14 85.7 1.0 0.1 120 Table.6 Minimum input voltage start-up slew rate and start-up timeDetailed Description The MYTNA1R84RELA2RA is a two-stage DCDC converter that is composed of a dual-phase charge pump- based DCDC converter and a dual-phase synchronous buck DCDC converter. The output voltage range supported from 0.7 to 1.8V (The output voltage range depend on the input voltage.) with load currents of up to 4A and up to 7.2W delivered to the external load. This module isn’t designed for the parallel operation. Output Voltage Adjustment The output voltage may be adjusted over a limited range by connecting an external trim resistor (Rtrim) between the Trim pin and AGND pin. The Rtrim must be a 1/10W (or larger) precision metal film type,±0.5% accuracy (or better) with low temperature coefficient, ±100 ppm/°C (or better). Mount the resistor close to the converter with very short leads or use a surface mount trim resistor. And do not connect any additional components between the Trim pin and Vout or between the Trim and Sense pins. Use only the specified connections. Resistor Trim Equation Rtrim[kohm] = 0.7164/(VOUT − 0.597) (eq.2)