PM6670AS STMicroelectronics, PM6670AS Datasheet - Page 29

• Manufacturer Part Number: PM6670AS
• Description: IC CTLR DDR2/3 MEM PS VFQFPN-24
• Manufacturer: STMicroelectronics

Specifications of PM6670AS

• Applications: Memory, DDR2/DDR3 Regulator
• Current - Supply: 800µA
• Voltage - Supply: 4.5 V ~ 28 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-VFQFN, 24-VFQFPN
• For Use With: 497-8412 - BOARD EVAL PM6670AS DDR2/3497-8411 - BOARD EVAL PM6670S DDR2/3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PM6670AS
7.1.4
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 T
rectifier is enabled until the inductor current reaches the zero-crossing threshold (see
Figure 32
Figure 32.
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
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.
R8
R8
R9
R9
VDDQ
VDDQ
Inductor
current
).
VDDQ
Output
V
reg
Inductor current and output voltage at light load with non-audible pulse-skip
T
+5V
+5V
ON
T
OFF
(a)
(a)
DDRSEL
DDRSEL
MODE
MODE
Doc ID 14436 Rev 2
PM6670
PM6670
PM6670AS
T
MAX
T
IDLE
ON
period and, once it has expired, the synchronous
R9
R9
R8
R8
VDDQ
VDDQ
V
V
REF
REF
+5V
+5V
(b)
(b)
DDRSEL
DDRSEL
MODE
MODE
Device description
PM6670AS
PM6670
PM6670
t
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