L6725_07 STMICROELECTRONICS [STMicroelectronics], L6725_07 Datasheet - Page 11

• Manufacturer Part Number: L6725_07
• Description: Voltage mode PWM controller with bootstrap anti-discharging system
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

L6725 - L6725A
5.3
Figure 3.
5.4
Bypassing the LDO to avoid the voltage drop with low Vcc
If V
maximum LDO output current is about 100mA and so the output voltage drop is 100mV, to
avoid this the LDO can be bypassed.
Internal and external references
It is possible to set the internal/external reference and the switching frequency by setting the
proper voltage at the EAREF pin. The maximum value of the external reference depends on the
V
maximum external reference is 2.5V (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 100K pull-down resistor is integrated into
the device (see
pin is captured by the device at the start-up when V
CC
Bypassing the LDO
CC
: with V
V
V
V
The minimum OVP threshold is set at 300mV;
The under-voltage-protection doesn't work;
≈
EAREF
EAREF
EAREF
5V the internal LDO works in dropout with an output resistance of about 1Ω. The
CC
from 0% to 80% of V
from 80% to 95% of V
from 95% to 100% of V
= 4V the clamp operates at about 2V (typ.), while with V
Figure
4.). Finally it must be taken into account that the voltage at the EAREF
CCDR
CCDR
CCDR
-> External reference/Fsw = 250KHz
-> V
-> V
REF
REF
= 0.6V/Fsw = 500KHz
= 0.6V/Fsw = 250KHz
CC
is about 4V.
CC
greater than 5V the
Device description
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