VOL: As table 2 suggests,
TL and ATL devices have VOL close to 2 V and TLV and TLVH devices have VOL close
to 1 V. Please refer to application note SLVA987 for
more detail of VOL variation over IKA, IREF and temperature.
Propagation delay:
Designers prefer fast response in the comparator mode in their designs. Faster
response of the comparator mode in power vsupply design saves power by
switching the PWM controller faster in the design example given in the figure.
Table 4-2
lists the typical TPHL for 431 devices when the supply is ramped up from 4.5 V
to 6 V to the output of the comparator settles within 5% of the VOL value for
the no load capacitor.
Table 4-2 Typical Propagation Delay
(Settled Response) of Devices
Device
TPHL (μs)
TL431
1.5
TL431LI
1.2
ATL431
10
ATL431LI
1.2
Below are the scope shots for TPLH for
different devices.
Figure 4-2 Propagation Delay (TPLH):
TL431
Figure 4-3 Propagation Delay (TPLH):
TL431LI
Figure 4-4 Propagation Delay (TPLH):
ATL431
Figure 4-5 Propagation Delay (TPLH):
ATL431LI
Shunt regulators from TI (TL431 ,
TL431, ATL431 & ATL431LI) have < 10 us typical response time and can be used
for faster systems.