STEVAL-ISA051V2 STMicroelectronics, STEVAL-ISA051V2 Datasheet - Page 21

• 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

PM6670AS
The duty-cycle of the buck converter is, in steady-state conditions, given by
Equation 2
The switching frequency is thus calculated as
Equation 3
where
Equation 4a
Equation 4b
Referring to the typical application schematic (figures on cover page and
final expression is then:
Equation 5
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's DCR) introduce voltage drops responsible for slight dependence on load current.
In addition, the internal delay is due to a small dependence on input voltage. The
PM6670AS switching frequency can be set by an external divider connected to the VOSC
pin.
f
SW
Doc ID 14436 Rev 2
=
f
SW
T
D
ON
=
K
α
=
α
OSC
OSC
α
K
OSC
OUT
D
OSC
=
V
=
V
OUT
=
=
V
--------------
IN
R
V
V
V
OUT
1
V
-------------- -
--------------
V
OSC
V
SNS
IN
R
V
+
OSC
OUT
SNS
2
IN
R
2
=
⋅
α
α
K
OSC
OUT
OSC
1
⋅
K
OSC
1
Device description
Figure 27
), the
21/53