L6591 STMicroelectronics, L6591 Datasheet - Page 28

• 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

Application information
6.6
28/41
Figure 47. Operation after latched disable activation: timing diagram
This function is useful to implement a latched over temperature protection very easily by
biasing the pin with a divider from VREF, where the upper resistor is an NTC physically
located close to a heating element like the MOSFET, or the secondary diode or the
transformer. An OVP can be implemented as well, e.g. by sensing the output voltage and
transferring an overvoltage condition via an optocoupler.
Oscillator and dead-time programming
The oscillator is programmed externally by means of a resistor-capacitor network (R
connected from pin OSC (#5) to VREF (#6) and to ground respectively. Once chosen the
oscillator frequency and the dead-time duration needed, the values of RT and CT can be
calculated as:
Equation 1
Equation 2
After having selected the commercial values for R
can be verified with good approximation using the following formula:
Vcc
LVG, H VG
P FC_ STOP
on
- 1
Vcc
VH
V cc
Vcc
Vcc
DIS
4 .5V
re sta rt
Vin
sta rt
o ff
on
Doc ID 14821 Rev 5
R
C
H V g ene ra to r i s turn ed on
T
T
=
=
50
. 1
39
+
f
⋅
osc
f
osc
1
(
T
d
⋅
R
1150
−
R
T
T
125
T
(
R
and C
−
T
Inpu t sou rce i s re moved he re
1200
⋅
10
−
HV gen erator tu rn-on i s d isabl ed he re
50
−
T
9
, the oscillator frequency (f
)
)
Disa ble la tch i s re set h ere
T
, C
osc
L6591
t
t
t
t
T
)
)