Delta Electronics IPM24S0B0 Test Configurations, Design Considerations, Input Source Impedance

TEST CONFIGURATIONS

	TO OSCILLOSCOPE
	L		VI(+)
BATTERY	2	100uF	3.3uF
			Ceramic
	Electrolytic
			VI(-)

Note: Input reflected-ripple current is measured with a simulated source inductance. Current is measured at the input of the module.

Figure 23: Input reflected-ripple current test setup

COPPER STRIP

Vo

220uF	1uF	SCOPE	Resistive
			Load
PosCap	ceramic

GND

Note: Use a 220µF PosCap and 1µF capacitor. Scope measurement should be made using a BNC connector.

Figure 24: Peak-peak output noise and startup transient measurement test setup

				CONTACT AND
				DISTRIBUTION LOSSES
		VI	Vo
	II				Io
SUPPLY						LOAD
		GND

CONTACT RESISTANCE

Figure 25: Output voltage and efficiency measurement test setup

Note: All measurements are taken at the module terminals. When the module is not soldered (via socket), place Kelvin connections at module terminals to avoid measurement errors due to contact resistance.

η = (Vo ⋅ Io) ⋅100 %

DS_IPM24S0B0_03202007Vi ⋅ Ii

DESIGN CONSIDERATIONS

Input Source Impedance

To maintain low-noise and ripple at the input voltage, it is critical to use low ESR capacitors at the input to the module. Figure 26 shows the input ripple voltage (mVp-p) for various output models using 2x100uF low ESR electrolytic capacitors (Rubycon P/N:50YXG100, 100uF/50V or equivalent) and 1x3.3.0 uF very low ESR ceramic capacitors (TDK P/N: C4532JB1H335M, 3.3uF/50V or equivalent).

The input capacitance should be able to handle an AC ripple current of at least:

Irms	=	Iout	Vout	⎛	−	Vout	⎞
			Vin	⎜ 1		Vin	⎟ Arms
				⎝			⎠

Figure 26: Input ripple voltage for various output models, Io = 3A (Cin =2x100uF electrolytic capacitors 1x3.3uF ceramic capacitors at the input)

The power module should be connected to a low ac-impedance input source. Highly inductive source impedances can affect the stability of the module. An input capacitance must be placed close to the modules input pins to filter ripple current and ensure module stability in the presence of inductive traces that supply the input voltage to the module.

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