L6730TR STMicroelectronics, L6730TR Datasheet - Page 18

• Manufacturer Part Number: L6730TR
• Description: IC CTRLR ADJ STEP DOWN 20-TSSOP
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L6730TR

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: Adj to 0.6V
• Frequency - Switching: 100kHz ~ 1MHz
• Voltage - Input: 1.8 ~ 14 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP Exposed Pad, 20-eTSSOP, 20-HTSSOP
• Output Voltage: 0.6 V
• Input Voltage: 1.8 V to 14 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• For Use With: 497-5868 - EVAL BOARD 30A 400KHZ L6730497-5501 - EVAL BOARD FOR L6730XX
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-5098-2

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