PM6641 STMicroelectronics, PM6641 Datasheet - Page 32

• Manufacturer Part Number: PM6641
• Description: IC MONO VR DDR2/3 PC VFQFPN-48
• Manufacturer: STMicroelectronics

Specifications of PM6641

• Applications: Converter, DDR2, DDR3
• Voltage - Input: 2.7 ~ 5.5 V
• Number Of Outputs: 3
• Voltage - Output: 0.8 ~ 5.5 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-VFQFN
• Output Voltage: 0.9 V
• Output Current: 3 A
• Input Voltage: 2.7 V to 5.5 V
• Switching Frequency: 1000 KHz
• Operating Temperature Range: - 40 C to + 125 C
• Mounting Style: SMD/SMT
• For Use With: 497-8425 - KIT EVAL PM6641 CHIPSET/DDR2/3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Device description
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where VREF = 0.9V is the constant voltage forced by CSNS pin, R
connected between CSNS and AGND, α is the coefficient that collects the MOS current
sensing scaling factor and other design parameters and I
The following table resumes values for all the switching regulators.
Table 11.
The following graph is a plot of the switching regulators peak current limit, increasing the
R
Figure 33. SW regulators peak current limit
From the previous plot and table it’s clear that the three regulators peak current limits are
scaled; by changing the R
CSNS
resistor:
Typical SW regulators values
7.00
7.00
6.00
6.00
5.00
5.00
4.00
4.00
3.00
3.00
2.00
2.00
1.00
1.00
0.00
0.00
40
40
SW regulator
1.05V
1.8V
1.5V
60
60
CSNS
Doc ID 13510 Rev 3
external resistor the three peak current limits all change.
80
80
100
100
Rcsns [kOhm]
Rcsns [kOhm]
120
120
140
140
CL
is the peak current limit [A].
160
160
CSNS
333x10e3
222x10e3
278x10e3
CL_1V8
CL_1V8
CL_1V5
CL_1V5
CL_1V05
CL_1V05
α
[Ω] is the resistor
180
180
PM6641