PM6652 STMicroelectronics, PM6652 Datasheet - Page 26

• Manufacturer Part Number: PM6652
• Description: IC CTLR STEPDOWN SMPS 32VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6652

• Applications: Controller, Intel IMVP-6.5™, VR11
• Voltage - Input: 4.5 V ~ 36 V
• Number Of Outputs: 1
• Voltage - Output: 0.3 V ~ 1.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Device description
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Equation 1
where K
typ.).
This leads to a nearly constant switching frequency, regardless of input and output voltages.
When the output voltage goes lower than the internal programmed voltage (see
Droop function on page 29
high side MOSFET for a fixed on-time, allowing the inductor current to increase; after the on-
time, an off-time phase, in which the low side MOSFET is turned on, follows.
If the DPRSLPVR control pin is set low, the low-side MOSFET is turned off only when the
output voltage becomes lower than the programmed value again, and a new cycle begins. In
this working mode the switching frequency is almost load independent, as shown below.
Refer to
light load, high-efficiency algorithm.
The duty cycle of the buck converter, in steady state conditions, is given by
Equation 2
The switching frequency is thus calculated as
Equation 3
where
Equation 4
can be set by varying the external resistor ROSC, placed between VIN and VOSC pin. RINT
is the integrated switching frequency programming resistor (typ. 17 kΩ).
The resultant switching frequency is theoretically independent from battery and output
voltage; actually conduction losses due to MOSFET on resistance, inductor DCR and PCB
traces can slightly influence the programmed value.
OSC
Section 8.4: Differential remote sensing on page 29
is a constant value (140 ns typ.) and τ is the internal propagation delay (40 ns
f
SW
for details), the on-time one shot generator directly drives the
=
Doc ID 16867 Rev 3
T
α
D
ON
OSC
T
=
ON
K
=
OSC
V
=
V
D =
OSC
K
IN
V
V
OSC
V
V
OUT
IN
OUT
OSC
V
=
V
OUT
IN
V
V
R
OUT
OSC
+
INT
τ
R
+
≅
INT
+
R
α
τ
OSC
OSC
⋅
section for details about the
K
OSC
1
Section 8.5:
PM6652