L6591 STMicroelectronics, L6591 Datasheet - Page 25

• Manufacturer Part Number: L6591
• Description: IC CTRLR PWM PROG CM HV 16SOIC
• Manufacturer: STMicroelectronics

Specifications of L6591

• Output Isolation: Isolated
• Frequency Range: 168 ~ 192kHz
• Voltage - Input: 8.7 ~ 22 V
• Power (watts): 750mW
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Output Voltage: 5 V
• Input Voltage: 25 V
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: SMD/SMT
• Duty Cycle (max): 50 %
• For Use With: 497-8335 - BOARD EVAL FOR L6591
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-8286

L6591
Figure 43. Load-dependent operating modes: timing diagram
Figure 44. Addition of an offset to the current sense lowers the burst-mode
To help the designer meet energy saving requirements even in power-factor-corrected
systems, where a PFC pre-regulator precedes the DC-DC converter, the L6591 allows that
the PFC pre-regulator can be turned off during burst-mode operation, hence eliminating the
no-load consumption of this stage (0.5÷1 W). There is no compliance issue in that because
EMC regulations on low-frequency harmonic emissions refer to nominal load, no limit is
envisaged when the converter operates with light or no load.
To do so, the L6591 provides the PFC_STOP (#8) pin: it is an open collector output,
normally open, that is asserted low when the IC is idle during burst-mode operation. This
signal will be externally used for switching off the PFC controller and the pre-regulator as
shown in
controller starts first.
GATE-DR IVE
PF C_STOP
L VG, HVG
PFC
COMP
f
1.82V
1.75V
osc
Figure
operation threshold
Fi x. Fr eq . M od e
45. When the L6591 is in UVLO the pin is kept open, to let the PFC
Vref
Vref
Doc ID 14821 Rev 5
L6591
L6591
6
6
11
11
Bu rst-mo d e
GND
GND
10
10
4
4
V
V
o
o
LVG
LVG
ISEN
ISEN
= Vref
= Vref
Rc
Rc
R + Rc
R + Rc
R
R
R
R
Fi x. Fre q . Mo de
Rs
Rs
Application information
t
t
t
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