STEVAL-ISA051V1 STMicroelectronics, STEVAL-ISA051V1 Datasheet - Page 21
![BOARD EVAL PM6670S DDR2/3](/photos/9/13/91334/steval-isa051v1_sml.jpg)
STEVAL-ISA051V1
Manufacturer Part Number
STEVAL-ISA051V1
Description
BOARD EVAL PM6670S DDR2/3
Manufacturer
STMicroelectronics
Type
DC/DC Switching Converters, Regulators & Controllersr
Specifications of STEVAL-ISA051V1
Design Resources
STEVAL-ISA051V1 Gerber Files STEVAL-ISA051V1 Schematic STEVAL-ISA051V1 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 ~ 28V
Regulator Topology
Buck
Board Type
Fully Populated
Utilized Ic / Part
PM6670
Input Voltage
4.5 V to 28 V
Output Voltage
1.8 V, 1.5 V
Product
Power Management Modules
Silicon Manufacturer
ST Micro
Silicon Core Number
PM6670S
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
PM6670S
Other names
497-8411
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
STEVAL-ISA051V1
Manufacturer:
STMicroelectronics
Quantity:
1
PM6670S
7.1
VDDQ section - constant on-time PWM controller
The PM6670S uses a pseudo-fixed frequency, constant on-time (COT) controller as the core
of the switching section. It is well known that the COT controller uses a relatively simple
algorithm and uses the ripple voltage derived across the output capacitor’s ESR to trigger
the on-time one-shot generator. In this way, the output capacitor’s ESR acts as a current
sense resistor providing the appropriate ramp signal to the PWM comparator. Nearly
constant switching frequency is achieved by the system’s loop in steady-state operating
conditions by varying the on-time duration, avoiding thus the need for a clock generator. The
on-time one shot duration is directly proportional to the output voltage, sensed at VSNS pin,
and inversely proportional to the input voltage, sensed at the VOSC pin, as follows:
Equation 1
where K
typ.). The one-shot generator directly drives the high-side MOSFET at the beginning of each
switching cycle allowing the inductor current to increase; after the on-time has expired, an
Off-Time phase, in which the low-side MOSFET is turned on, follows. The off-time duration
is solely determined by the output voltage: when lower than the set value (i.e. the voltage at
VSNS pin is lower than the internal reference V
off and a new cycle begins
Figure 28. Inductor current and output voltage in steady state conditions
OSC
is a constant value (130 ns typ.) and τ is the internal propagation delay (40ns
Inductor
Inductor
current
current
Output
Output
voltage
voltage
V
V
reg
reg
(Figure
Ton
Ton
Doc ID 14432 Rev 4
T
28).
ON
=
Toff
Toff
K
OSC
V
V
R
OSC
SNS
= 0.9 V), the synchronous rectifier is turned
+
τ
t
t
Device description
21/54