HA16150T Datasheet, PDF (14/25 Pages) Renesas Technology Corp – High-Speed Current Mode Push-Pull PWM Control IC

HA16150T/P
Soft start time tss is determined by SS pin connection capacitance Css and an internal constant, and can be estimated
using the equation shown below.
Soft start time tss is the time until the first pulse is output to the driver output OUT pin after VREF starts up following
UVLO release.
This is equivalent to the time until the SS pin voltage reaches IC-internal SS comparator reference voltage VTL (1.1 V),
and can be calculated using the approximate equation shown below.
Soft start time tss when Css is 1000pF is given by the following equation.
tss = ^{Css × VTL} =
Iss
1000 [pF] × 1.1 [V]
5 [µA]
≈ 220 [µs]
* Iss: SS pin source current, 5 µA typ.
Note: A soft start circuit operates only once at the start-up of the IC (after the VREF pin voltage is launched and the
VrefGOOD circuit is operated). If the SS pin is lowered to 1.1 V or less after the SS pin becomes once high,
the pulse of OUT1 and OUT2 is not halt. Each duty cycle of OUT1 and OUT2 is fixed to 25%.
4. Dead Band Generation Circuit
"Dead band" refers to the time when both push-pull dual outputs are off.
By setting the dead band time arbitrarily, it is possible to configure a system in which the dual outputs are never on
simultaneously with respect to input and load variations.
V_CT
V_TDB
SS comp. out
(internal signal)
OUT1
0.5V
OUT2
Figure 5
Dead band time tdb is determined by TDB pin connection capacitance Cdb and an internal constant, and can be
estimated using the equation shown below.
Even when the TDB pin is open, the dead band time does not become zero due to floating capacitance of the IC package,
etc. This dead band time is designated tdb0.
Dead band time tdb when Cdb is 47 pF is given by the following equation.
tdb = tdb0 + ^{Cdb × Vth} = tdb0 +
Idb
47 [pF] × 0.5 [V]
300 [µA]
= 60 [ns] + 78 [ns]
= 138 [ns]
* Idb: TDB pin source current, 300 µA typ.
* Vth: IC-internal TDB comparator reference voltage
Rev.3.00 Jan 30, 2007 page 14 of 24