Datasheet MYTNA1R86RELA2RA (Murata) - 9

MYTNA1R86RELA2RA
Document Category: Datasheet UltraBK™ 6A 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
OUTPUT
VOLTAGE(V) 1.8
1.2
1.0 (eq.1) CALCULATION EXAMPLE
VINSR_L(V/ms)
0.26
0.14
0.1 VIN RISE TIME(ms)
(0V to 12V)
46.2
85.7
120 Table.6 Minimum input voltage start-up slew rate and start-up time Detailed Description
The MYTNA1R86RELA2RA is a two-stage DCDC converter that is composed of a dual-phase charge pumpbased 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 6A
and up to 10.8W 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. Also, avoid high noise at the trim pin. However, to prevent
instability, you should never connect any capacitors between trim pin and GND pin. 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) The equations above are only reference, so please be sure to check the output voltage and adjust Rtrim in user
circumstances. To increase or decrease the output voltage, increase or decrease the Rtrim value. http://www.murata.com/products/power
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