EVAL6730 STMicroelectronics, EVAL6730 Datasheet - Page 18

• Manufacturer Part Number: EVAL6730
• Description: EVAL BOARD FOR L6730XX
• Manufacturer: STMicroelectronics
• Type: Motor / Motion Controllers & Driversr

Specifications of EVAL6730

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Power - Output: 66W
• Voltage - Output: 3.3V
• Current - Output: 20A
• Voltage - Input: 4.5 ~ 14V
• Regulator Topology: Buck
• Frequency - Switching: 400kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6730
• Input Voltage: 8 V to 52 V
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: L6208
• Other names: 497-5501

Device description
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The output of the error amplifier is clamped with this voltage (Vss) until it reaches the
programmed value. No switching activity is observable if V
MOSFETs are off. When Vss is between 0.5 V and 1.1 V the low-side MOSFET is turned on
because the output of the error amplifier is lower than the valley of the triangular wave and
so the duty-cycle is 0%. As V
limit) even the high-side MOSFET begins to switch and the output voltage starts to increase.
The L6730 - L6730B can only source current during the soft-start phase in order to manage
the pre-bias start-up applications. This means that when the startup occurs with output
voltage greater than 0V (pre-bias startup), even when Vss is between 0.5 V and 1.1 V the
low-side MOSFET is kept OFF (see
Figure 9.
Figure 10. Start-up with pre-bias
The L6730B can always sink current and so it can be used to supply the DDR memory
termination BUS. If overcurrent is detected during the soft-start phase, the device provides
constant current-protection. In case there is short soft-start time and/or small inductor value
and/or high output capacitors value and thus, in case of high ripple current during the soft-
start, the converter can start-up in anyway and limit the current
Start-up without pre-bias
SS
Doc ID 11938 Rev 3
reaches 1.1 V (i.e. the oscillator triangular wave inferior
Figure 9
and
Figure
10).
SS
is lower than 0.5 V and both
(Chapter 5.8: Monitoring and
LGate
V
V
LGate
V
I
SS
V
OUT
L
OUT
SS
I
L
L6730 - L6730B