PM6641 STMicroelectronics, PM6641 Datasheet - Page 27

• 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

PM6641
7.5
Output voltage divider
PM6641 switching regulators are adjustable voltage converters.
If the feedback pin (VFB_1S8, VFB_1S5, VFB_1S05 respectively belonging to
VDDQ (1.8 V), 1.5 V, 1.05 V rail) is directly tied to the rail output capacitor the internal divider
with pre-fixed output voltage value is activated and the nominal output voltages are
selected.
If the feedback pin is connected to the output voltage divider central tap (as depicted in
Figure 30
Figure 30. SW regulator with external divider
the PM6641 switching regulator automatically recognizes the external divider and the output
voltage is regulated to the following value:
Equation 5
)
Doc ID 13510 Rev 3
Vout
R
R
1
2
_
1
Sxx
=
⎛
⎜ ⎜
⎝
VFB_1Sxx
Vout_1Sxx
R
R
2
1
+
1
⎞
⋅ ⎟ ⎟
⎠
0
8 .
V
Device description
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