SLVSH63 February 2023 TLVM13610
PRODUCTION DATA
Input capacitors are necessary to limit the input ripple voltage to the module due to switching-frequency AC currents. TI recommends using ceramic capacitors to provide low impedance and high RMS current rating over a wide temperature range. Equation 2 gives the input capacitor RMS current. The highest input capacitor RMS current occurs at D = 0.5, at which point the RMS current rating of the capacitors must be greater than half the output current.
where
Ideally, the DC and AC components of input current to the buck stage are provided by the input voltage source and the input capacitors, respectively. Neglecting inductor ripple current, the input capacitors source current of amplitude (IOUT – IIN) during the D interval and sink IIN during the 1 – D interval. Thus, the input capacitors conduct a square-wave current of peak-to-peak amplitude equal to the output current. The resultant capacitive component of AC ripple voltage is a triangular waveform. Together with the ESR-related ripple component, Equation 3 gives the peak-to-peak ripple voltage amplitude:
Equation 4 gives the input capacitance required for a particular load current:
where
The TLVM13610 requires a minimum of two 10-µF ceramic input capacitors, preferably with X7R or X7S dielectric and in 1206 or 1210 footprint. Additional capacitance can be required for applications to meet conducted EMI specifications, such as CISPR 11 or CISPR 32.
#GUID-E6757F0A-FD9F-4C2B-A5BA-8A9C94F3D8F0/SNVSA92_INPUTCAPS includes a preferred list of capacitors by vendor. To minimize the parasitic inductance in the switching loops, position the ceramic input capacitors in a symmetrical layout close to the VIN1 and VIN2 pins and connect the capacitor return terminals to the PGND pins using a copper ground plane under the module.
VENDOR(1) | DIELECTRIC | PART NUMBER | CASE SIZE | CAPACITANCE (µF)(2) | RATED VOLTAGE (V) |
---|---|---|---|---|---|
TDK | X7R | C3216X7R1H106K160AC | 1206 | 10 | 50 |
Murata | X7S | GCM32EC71H106KA03K | 1210 | 10 | 50 |
AVX | X7R | 12105C106MAT2A | 1210 | 10 | 50 |
Murata | X7R | GRM32ER71H106KA12L | 1210 | 10 | 50 |
As discussed in Power Supply Recommendations, an electrolytic bulk capacitance (68 µF to 100 µF) provides low-frequency filtering and parallel damping to mitigate the effects of input parasitic inductance resonating with the low-ESR, high-Q ceramic input capacitors.