STEVAL-ISA051V2 STMicroelectronics, STEVAL-ISA051V2 Datasheet - Page 30
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STEVAL-ISA051V2
Manufacturer Part Number
STEVAL-ISA051V2
Description
BOARD EVAL PM6670AS DDR2/3
Manufacturer
STMicroelectronics
Type
DC/DC Switching Converters, Regulators & Controllersr
Specifications of STEVAL-ISA051V2
Design Resources
STEVAL-ISA051V2 Gerber Files STEVAL-ISA051V2 Schematic STEVAL-ISA051V2 Bill of Material
Main Purpose
Special Purpose DC/DC, DDR Memory Supply
Outputs And Type
4, Non-Isolated
Voltage - Output
1.5V, 1.8V
Voltage - Input
4.5 ~ 36V
Regulator Topology
Buck
Board Type
Fully Populated
Utilized Ic / Part
PM6670A
Input Voltage
4.5 V to 36 V
Output Voltage
1.8 V, 1.5 V
Product
Power Management Modules
Silicon Manufacturer
ST Micro
Silicon Core Number
PM6670AS
Kit Application Type
Power Management
Application Sub Type
DDR2/3 Memory Power Supply Controller
Kit Contents
Board
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Current - Output
-
Power - Output
-
Frequency - Switching
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
For Use With/related Products
PM6670AS
Other names
497-8412
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
STEVAL-ISA051V2
Manufacturer:
STMicroelectronics
Quantity:
1
Device description
7.1.5
30/53
When the MODE pin is connected to +5 V, the PM6670AS allows setting the VDDQ voltage
to 1.8 V or 1.5 V just forcing the DDRSEL multilevel pin to +5 V or to ground respectively
(see
In this condition the pulse-skip feature is enabled. This device configuration is suitable for
standard DDR2/3 memory supply applications avoiding the need for an external, high
accuracy, divider for output voltage setting.
Applications requiring different output voltages can be managed by PM6670AS simply
setting the adjustable mode. If MODE pin voltage is higher than 4 V, the fixed output mode is
selected. Connecting an external divider to the MODE pin (
negative input of the error amplifier and the output voltage is given by expression (21).
Equation 21
VDDQ output voltage can be set in the range from 0.9 V to 2.6 V. Adjustable mode
automatically switches DDRSEL pin to become the power saving algorithm selector: if tied
to +5 V, the forced-PWM (fixed frequency) control is performed. If grounded or connected to
VREF pin (1.237 V reference voltage), the pulse-skip or non-audible pulse-skip modes are
respectively selected.
Table 8.
Current sensing and current limit
The PM6670AS switching controller uses a valley current sensing algorithm to properly
handle the current limit protection and the inductor current zero-crossing information. The
current is sensed during the conduction time of the low-side MOSFET. The current sensing
element is the on-resistance of the low-side switch. The sensing scheme is visible in
Figure 34
V
V
Figure 33
MODE
MODE
Mode
.
> 4.3 V
< 3.7 V
Mode-of-operation settings summary
a).
1 V < V
1V < V
V
V
V
DDRSEL
DDRSEL
DDRSEL
DDRSEL
DDRSEL
DDRSEL
<0.5 V
Doc ID 14436 Rev 2
VDDQ
> 4.2 V
> 4.2 V
< 0.5 V
< 3.5 V
< 3.5 V
ADJ
=
0
9 .
VDDQ
1.8 V
1.5 V
ADJ
⋅
R
8
R
+
8
R
9
Figure 33
Non-Audible Pulse-skip
Operating mode
Forced-PWM
b), it is used as
Pulse-Skip
Pulse-Skip
PM6670AS