米6体育平台手机版

SNVA881 November 2019 LP87521-Q1 , LP87522-Q1 , LP87523-Q1 , LP87524-Q1 , LP87525-Q1 , LP87561-Q1 , LP87562-Q1 , LP87563-Q1 , LP87564-Q1 , LP87565-Q1

Stability Considerations for LP8756x-Q1 and LP8752x-Q1

4.2 Measurement Results

Typical Bode diagrams for every phase configuration are shown in Figure 2, Figure 3, Figure 4 and Figure 5. Each configuration has 1000 mV output voltage and 44 µF POL capacitance.

Figure 2. V_OUT=1000 mV, C_POL=44 µF/phase, 1-phase configuration

Figure 4. V_OUT=1000 mV, C_POL=44 µF/phase, 3-phase configuration

Figure 3. V_OUT=1000 mV, C_POL=44 µF/phase, 2-phase configuration

Figure 5. V_OUT=1000 mV, C_POL=44 µF/phase, 4-phase configuration

All measurement results are listed in Table 3, Table 4, Table 5 and Table 6 for each phase configuration. Results marked with N/A were not possible to measure due to the limitations in the measurement hardware as mentioned in Section 4.1. These results can be used when selecting point of load capacitance to fulfill phase margin requirements on specific V_IN and V_OUT.

Table 3. Measured gain and phase margins for 1-phase configuration

V_IN (V)	V_OUT (mV)	C_POL (µF/phase)	Bandwidth (kHz)	Gain margin (dB)	Phase margin (deg)
3.3	860	22	193.2	18.3	30.3
		44	147.7	31.1	36.9
		91	101.7	38.5	48.5
	1000	22	201.2	17.8	32.0
		44	152.4	35.3	39.1
		91	104.4	N/A	50.4
	1800	22	224.5	17.3	38.8
		44	167.4	29.2	46.0
		91	116.2	36.1	55.3
5.0	860	22	229.6	19.6	34.0
		44	172.0	N/A	41.0
		91	114.6	N/A	52.0
	1000	22	219.0	19.9	30.8
		44	164.7	N/A	37.5
		91	112.1	N/A	48.4
	1800	22	245.7	17.7	39.2
		44	181.4	30.9	45.4
		91	124.9	39.4	55.4
	3300	22	296.9	13.8	45.4
		44	207.5	26.9	51.9
		91	152.5	26.2	58.1

Table 4. Measured gain and phase margins for 2-phase configuration

V_IN (V)	V_OUT (mV)	C_POL (µF/phase)	Bandwidth (kHz)	Gain margin (dB)	Phase margin (deg)
3.3	860	22	188.2	19.0	31.9
		44	143.9	35.4	39.1
		91	95.2	N/A	50.4
	1000	22	193.6	18.7	33.2
		44	147.5	N/A	40.3
		91	99.6	N/A	50.7
	1800	22	209.8	18.6	36.3
		44	158.8	N/A	43.3
		91	110.7	N/A	52.3
5.0	860	22	223.4	22.0	35.9
		44	168.1	34.5	43.7
		91	108.3	N/A	54.0
	1000	22	210.7	21.7	34.6
		44	159.4	38.4	41.0
		91	105.7	N/A	52.2
	1800	22	236.3	20.6	39.9
		44	174.0	N/A	46.9
		91	119.4	N/A	55.0
	3300	22	273.3	16.3	44.8
		44	194.2	26.8	50.3
		91	137.0	27.8	56.5

Table 5. Measured gain and phase margins for 3-phase configuration

V_IN (V)	V_OUT (mV)	C_POL (µF/phase)	Bandwidth (kHz)	Gain margin (dB)	Phase margin (deg)
3.3	860	22	186.7	21.3	31.2
		44	144.2	36.7	38.8
		91	100.5	N/A	48.3
	1000	22	193.7	19.9	32.7
		44	147.4	41.5	39.8
		91	102.6	N/A	49.8
	1800	22	209.2	19.4	36.3
		44	157.0	37.7	42.6
		91	111.4	N/A	51.5
5.0	860	22	246.4	21.2	36.1
		44	183.1	32.9	45.6
		91	122.2	N/A	55.5
	1000	22	223.9	20.7	35.0
		44	166.2	35.6	42.4
		91	112.5	N/A	51.5
	1800	22	241.3	19.8	39.2
		44	175.8	29.5	46.2
		91	123.0	N/A	53.7
	3300	22	287.8	15.9	42.4
		44	204.6	25.8	50.1
		91	146.5	27.1	55.1

Table 6. Measured gain and phase margins for 4-phase configuration

V_IN (V)	V_OUT (mV)	C_POL (µF/phase)	Bandwidth (kHz)	Gain margin (dB)	Phase margin (deg)
3.3	860	22	180.7	20.6	31.6
		44	136.9	N/A	38.3
		91	95.3	N/A	48.6
	1000	22	189.7	20.3	32.8
		44	143.3	N/A	40.0
		91	99.5	N/A	49.4
	1800	22	207.6	23.4	36.5
		44	153.7	N/A	42.8
		91	109.7	N/A	50.8
5.0	860	22	261.0	N/A	38.0
		44	194.7	N/A	48.9
		91	129.5	N/A	59.8
	1000	22	240.6	N/A	38.1
		44	170.7	N/A	45.7
		91	113.4	N/A	54.0
	1800	22	231.4	31.7	39.8
		44	169.0	N/A	47.4
		91	118.4	N/A	54.2
	3300	22	263.7	28.2	44.9
		44	197.2	28.1	50.1
		91	137.4	N/A	55.0