MAX17528GTJ+ Maxim Integrated Products, MAX17528GTJ+ Datasheet - Page 30

• Manufacturer Part Number: MAX17528GTJ+
• Description: IC PWM CTRLR STP-DWN 32TQFN-EP
• Manufacturer: Maxim Integrated Products
• Series: Quick-PWM™r

Specifications of MAX17528GTJ+

• Applications: Controller, Intel IMVP-6.5™ GMCH
• Voltage - Input: 4.5 ~ 5.5 V
• Number Of Outputs: 1
• Voltage - Output: 0.01 ~ 1.5 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 32-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 7. Fast Render GMCH Sleep Transition
1-Phase Quick-PWM
Intel IMVP-6.5/GMCH Controllers
During soft-shutdown and normal operation—when the
CPU is actively running (SKIP = low, Table 3), the
MAX17528 operates with the low-noise, forced-PWM
control scheme. Forced-PWM operation disables the
zero-crossing comparator, forcing the low-side gate-
drive waveforms to constantly be the complement of
the high-side gate-drive waveforms. This keeps the
switching frequency constant and allows the inductor
current to reverse under light loads, providing fast,
accurate negative output-voltage transitions by quickly
discharging the output capacitors.
Forced-PWM operation comes at a cost: the no-load
+5V bias supply current remains between 10mA to
50mA, depending on the external MOSFETs and switch-
ing frequency. To maintain high efficiency under light-
load conditions, the processor can switch the controller
to a low-power pulse-skipping control scheme after
entering suspend mode. The MAX17528 automatically
uses pulse-skipping operation during soft-start, regard-
less of the SKIP configuration.
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GFXDPRSLPVR
NOTE: GFXDPRSLPVR = SKIP = SLOW.
Forced-PWM Operation (Normal Mode)
VID (D0–D6)
ACTIVE VID
CPU CORE
VOLTAGE
PWRGD
DH
BLANK HIGH IMPEDANCE
20µs typ
t
BLANK
DEEPER SLEEP VID
PULSE SKIPPING
During soft-start and sleep states—SKIP is pulled
high—the MAX17528 operates in pulse-skipping mode.
The pulse-skipping mode enables the driver’s zero-
crossing comparator, so the controller pulls DL low
when the low-side MOSFET voltage drop (LX to GND
voltage) detects “zero” inductor current. This keeps the
inductor from sinking current and discharging the output
capacitors and forces the controller to skip pulses under
light-load conditions to avoid overcharging the output.
Upon entering pulse-skipping operation, the controller
temporarily blanks the upper PWRGD and CLKEN
thresholds, when the transition to pulse-skipping opera-
tion coincides with a VID code change. Once the error
amplifier detects that the output voltage is in regulation,
the upper PWRGD and upper CLKEN, resume tracking
the selected VID DAC code. The MAX17528 automati-
cally uses forced-PWM operation during soft-shutdown,
regardless of the SKIP configuration.
Light-Load Pulse-Skipping Operation
10mV/µs
BLANK HIGH IMPEDANCE
20µs typ
t
BLANK
1-PHASE FORCED PWM
ACTIVE VID
DPRSLP VID