L6731DTR STMicroelectronics, L6731DTR Datasheet - Page 11

• Manufacturer Part Number: L6731DTR
• Description: IC CTRLR ADJ STPDN SYNC 16-TSSOP
• Manufacturer: STMicroelectronics

Specifications of L6731DTR

• Applications: Controller, DDR
• Voltage - Input: 1.8 ~ 14 V
• Number Of Outputs: 1
• Voltage - Output: Adjustable down to 0.6V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP Exposed Pad, 16-eTSSOP, 16-HTSSOP
• Output Voltage: 0.6 V to 18 V
• Input Voltage: 1.8 V to 14 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6112-2

L6731D
5.3
5.4
Bypassing the LDO to avoid the voltage drop with low Vcc
If V
maximum LDO output current is about 100 mA and so the output voltage drop is 100 mV, to
avoid this the LDO can be bypassed.
Figure 4.
Internal and external references
It is possible to set the internal/external reference and the switching frequency by setting the
proper voltage at the DDR-IN pin. The maximum value of the external reference is 2.5 V
(typ.):
Providing an external reference from 0V to 450mV the output voltage will be regulated but
some restrictions must be considered:
To set the resistor divider it must be considered that a 100 k pull-down resistor is integrated
into the device (see
DDR-IN pin is captured by the device at the start-up when V
CC
≈
5 V the internal LDO works in dropout with an output resistance of about 1 Ω. The
●
●
●
●
●
●
Bypassing the LDO
V
V
V
OV threshold saturates to a minimum value of 300 mV (OV is tracking the
reference; tracking small references will result in a narrow threshold reducing
noise immunity)
The under-voltage-protection doesn't work;
The PGOOD signal remains low;
EAREF
EAREF
EAREF
Figure
from 0 % to 80 % of V
from 80 % to 95 % of V
from 95 % to 100 % of V
5.). Finally it must be taken into account that the voltage at the
CCDR
CCDR
CCDR
-> External reference/F
-> V
-> V
REF
REF
CC
= 0.6 V/F
= 0.6 V/F
is about 4 V.
SW
SW
Device description
= 500 kHz
SW
= 250 kHz
= 250 kHz
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