STEVAL-ISA051V1 STMicroelectronics, STEVAL-ISA051V1 Datasheet - Page 47

• 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

PM6670S
8.1.6
VDDQ current limit setting
The valley current limit is set by R
current. The valley of the inductor current I
Equation 45
The output current limit depends on the current ripple as shown in
Figure 41. Valley current limit waveforms
As the valley threshold is fixed, the greater the current ripple, the greater the DC output
current will be. If an output current limit greater than I
range is required, the minimum current ripple must be considered in the previous formula.
Then the resistor R
Equation 46
where R
temperature effect and the worst case value in R
The accuracy of the valley current also depends on the offset of the internal comparator
(±6 mV).
The negative valley-current limit (if the device works in forced-PWM mode) is given by:
Equation 47
DSon
is the drain-source on-resistance of the low-side switch. Consider the
MAX LOAD 1
Current
Valley current limit
CSNS
Inductor current
is:
Doc ID 14432 Rev 4
I
CSNS
Lvalley
R
CSNS
I
NEG
and must be chosen to support the maximum load
=
Inductor current
I
=
LOAD
Lvalley
MAX LOAD 2
=
R
DSon
110
R
(max)
100
DSon
DSon
is:
mV
⋅
uA
I
Lvalley
−
LOAD
calculation (typically +0.4 %/°C).
Δ
2
I
L
(max) over all the input voltage
Application information
Figure 41
Time
:
47/54