PM6675AS STMicroelectronics, PM6675AS Datasheet - Page 43

• Manufacturer Part Number: PM6675AS
• Description: IC CTLR STP DWN HE LDO VFQFPN24
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of PM6675AS

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1.5V, 0.6 ~ 3.3 V
• Current - Output: ±1A, ±2A
• Frequency - Switching: 33kHz
• Voltage - Input: 4.5 ~ 36 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-VFQFN, 24-VFQFPN
• Power - Output: 2.3W
• For Use With: 497-8426 - KIT EVAL PM6675S HE CTLR 2A REG497-8413 - BOARD EVAL BASED ON PM6675A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PM6675AS
where k is a free design parameter greater than unity (k > 3) . It determinates the minimum
integrator capacitor value C
Equation 49
If the ripple on pin COMP is greater than the integrator output dynamic (150 mV), an
additional capacitor C
attenuation factor of the output ripple, select:
Equation 50
In order to reduce noise on pin COMP, it’s possible to introduce a resistor R
with C
or more times) than the switching frequency of the section:
Equation 51
For most of applications both R
If the ripple is very small (e.g. such as with ceramic capacitors), a further compensation
network, called “Virtual ESR” network, is needed. This additional part generates a triangular
ripple that substitutes the ESR output voltage ripple. The complete compensation scheme is
represented in
Figure 40. Virtual ESR network
Generation
INT
Block
Ton
and C
Figure 40
filt
, realizes a low pass filter. The cutoff frequency must be much greater (10
filt
could be added in order to reduce its amplitude. If q is the desired
.
PWM Comparator
INT
:
C
INT
R
INT
+
INT
-
and C
>
C
=
2
filt
2
⋅ π
VREF
⋅ π
filt
=
⎛
⎜ ⎜
⎝
f
C
CUT
f
are unnecessary.
SW
k
g
INT
m
C
−
C
⋅
q
1
1 (
INT
f
R
INT
Zout
−
INT
C
C
+
) q
⋅
FILT
⎞
⎟ ⎟
⎠
C
C
INT
⋅
FILT
FILT
Vref
Vo
Integrator
g
R
m
+
-
Application information
L
C
R1
0.6V
INT
that, together
VOUT
43/48