TPS652510 View Datasheet(PDF) - Texas Instruments

 Part Name Description Manufacturer TPS652510 4.5-V TO 16-V INPUT, HIGH CURRENT, SYNCHRONOUS STEP DOWN THREE DC-DC CONVERTERS WITH INTEGRATED FET Texas Instruments
TPS652510 Datasheet PDF : 31 Pages
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TPS652510
SLVSB30B – SEPTEMBER 2011 – REVISED AUGUST 2013
To calculate the external compensation components follow the following steps:
www.ti.com
Select switching frequency that is appropriate for
application depending on L, C sizes, output ripple, EMI
concerns and etc. Switching frequencies around 500 kHz
yield best trade off between performance and cost. When
using smaller L and C, switching frequency can be
increased. To optimize efficiency, switching frequency can
be lowered.
Select cross over frequency (fc) to be at least 1/5 to 1/10 of
switching frequency (fs).
Set and calculate Rc.
Calculate Cc by placing a compensation zero at or before
the converter dominant pole
1
fp =
CO × RL × 2p
Add CRoll if needed to remove large signal coupling to high
impedance CMP node. Make sure that
1
fpRoll = 2 ×p × RC × CRoll
is at least twice the cross over frequency.
Calculate Cff compensation zero at low frequency to boost
the phase margin at the crossover frequency. Make sure
that the zero frequency (fzff) is smaller than equivalent
soft-start frequency (1/Tss).
TYPE II CIRCUIT
Suggested
fc = fs/10
RC
=
2p
gM
× fc ×Vo ×Co
×Vref × gmps
Cc
=
RL × Co
Rc
CRoll
=
Re sr ×Co
RC
NA
TYPE III CIRCUIT
Type III circuit recommended for
switching frequencies higher than
500 kHz.
Suggested
fc = fs/10
RC
=
2p × fc ×Co
gM × gmps
Cc
=
RL × Co
Rc
CRoll
=
Re sr ×Co
RC
1
C ff = 2 ×p × fz ff × R1
Slope Compensation
The device has a built-in slope compensation ramp. The slope compensation can prevent sub harmonic
oscillations in peak current mode control.
Power Good
The PGOOD pin is an open drain output. The PGOOD pin is pulled low when any buck converter is pulled below
85% of the nominal output voltage. The PGOOD is pulled up when both buck converters’ outputs are more than
90% of its nominal output voltage.
The default reset time is 100 ms. The polarity of the PGOOD is active high.
18
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