PM6670S STMicroelectronics, PM6670S Datasheet - Page 40

• Manufacturer Part Number: PM6670S
• Description: IC CTLR DDR2/3 MEM PS VFQFPN-24
• Manufacturer: STMicroelectronics

Specifications of PM6670S

• Applications: Memory, DDR2/DDR3 Regulator
• Current - Supply: 800µA
• Voltage - Supply: 4.5 V ~ 36 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-VFQFN, 24-VFQFPN
• For Use With: 497-8411 - BOARD EVAL PM6670S DDR2/3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application information
40/54
where
Equation 27a
Equation 27b
Referring to the typical application schematic (figure in cover page and
expression is then:
Equation 28
The switching frequency directly affects two parameters:
●
●
Even if the switching frequency is theoretically independent from battery and output
voltages, parasitic parameters involved in power path (like MOSFETs on-resistance and
inductor DCR) introduce voltage drops responsible for a slight dependence on load current.
In addition, the internal delay is due to a light dependence on input voltage.
Table 12.
Inductor size: greater frequencies mean smaller inductances. In notebook applications,
real estate solutions (i.e. low-profile power inductors) are mandatory also with high
saturation and r.m.s. currents.
Efficiency: switching losses are proportional to the frequency. Generally, higher
frequencies imply lower efficiency.
R1 (kΩ)
330
330
330
330
330
330
Typical values for switching frequency selection
Doc ID 14432 Rev 4
f
SW
=
R2 (kΩ)
K
α
11
13
15
18
20
22
α
OSC
OSC
α
OSC
OUT
=
=
=
R
V
V
1
V
R
V
OSC
SNS
OUT
+
IN
2
R
2
⋅
K
Approx switching frequency (kHz)
OSC
1
250
300
350
400
450
500
Figure 29
), the final
PM6670S