PM6670AS View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'PM6670AS' PDF : 54 Pages View PDF
PM6670AS
Device description
has taken place within 30 μs (typ.) since the last one (because the output voltage is still
higher than the reference), a no-audible pulse-skip cycle begins. The low-side MOSFET is
turned on and the output is driven to fall until the reference has been crossed. Then, the
high-side switch is turned on for a TON period and, once it has expired, the synchronous
rectifier is enabled until the inductor current reaches the zero-crossing threshold (see
Figure 32).
Figure 32. Inductor current and output voltage at light load with non-audible pulse-skip
Inductor
current
7.1.4
VDDQ
Output
Vreg
TMAX
TON TOFF
TIDLE
t
For frequencies higher than 33 kHz (due to heavier loads) the device works in the same way
as in Pulse-Skip mode. It is important to notice that in both Pulse-Skip and No-Audible
Pulse-Skip modes the switching frequency changes not only with the load but also with the
input voltage.
Mode-of-operation selection
Figure 33. MODE and DDRSEL multifunction pin configurations
VDDQ
VDDQ
+5V
PPMM66667700AS
+5V
PMM66667700AS
R9
R9
MODE
MODE
R8
R8
VREF
DDRSEL
DDRSEL
(a)
(b)
The PM6670AS has been designed to satisfy the widest range of applications involving
DDR2/3 memories, SSTL15-18 buses termination and I/O supplies for CPU/Chipset. The
device is provided with multilevel pins which allow the user to choose the appropriate
configuration. The MODE pin is used to firstly decide between fixed preset or adjustable
(user defined) output voltages.
Doc ID 14436 Rev 2
29/53
Share Link: 
