ISL6263C Datasheet, PDF (10/18 Pages) Intersil Corporation – 5-Bit VID Single-Phase Voltage Regulator with Current Monitor for GPU Core Power

ISL6263C
VDD
−
OCP
+
+
−
10µA _↓
OCSET
ISP
+
Isense
−
ISN
ICOMP
VO
R_OCSET
PHASE
R_S
L_OUT
DCR
C_OUT
ESR
+
−
VDIFF
VSEN
RTN
C_FILTER1
R_FILTER1
R_FILTER2
C_FILTER2
C_FILTER3
V_OUT
V_GND
TO
PROCESSOR
KELVIN
CONNECTIONS
FIGURE 5. SIMPLIFIED GPU KELVIN SENSE AND INDUCTOR DCR CURRENT SENSE
VR_ON
~100µs
V_SOFT/ V_OUT
90%
PGOOD
13 SWITCHING CYCLES
FIGURE 4. ISL6263C START-UP TIMING
Static Regulation
The output voltage V_OUT will be regulated to the value set
by the VID inputs per Table 1. A true differential amplifier
connected to the VSEN and RTN pins implements processor
Kelvin sense for precise core voltage regulation at the GPU
voltage sense points.
The ISL6263C can accommodate DCR current sense or
discrete resistor current sense. The DCR current sense uses
the intrinsic series resistance of the output inductor, as
shown in the application circuit of Figure 2. The discrete
resistor current sense uses a shunt resistor in series with the
output inductor, as shown in the application circuit in
Figure 3. In both cases, the signal is fed to the non-inverting
input of the current sense amplifier at the ISP pin, where it is
measured differentially with respect to the output voltage of
the converter at the VO pin and amplified. The voltage at the
ICOMP pin minus the output voltage measured at the VO
pin, is proportional to the total inductor current. This
information is used for overcurrent protection and current
monitoring. It is important to note that this current
measurement should not be confused with the synthetic
current ripple information created within the R³ modulator.
When using inductor DCR current sense, an NTC
compensation network is optional to compensate the
positive temperature coefficient of the copper winding, thus
maintaining the current sense accuracy.
Processor Kelvin Voltage Sense
The remote voltage sense input pins VSEN and RTN of the
ISL6263C are to be terminated at the die of the GPU. Kelvin
sense allows the voltage regulator to tightly control the
processor voltage at the die, compensating for various
resistive voltage drops in the power delivery path.
Since the voltage feedback is sensed at the processor die,
removing the GPU will open the voltage feedback path of the
regulator, causing the output voltage to rise towards VIN.
The ISL6263C will shut down when the voltage between the
VO and VSS pins exceeds the severe overvoltage protection
threshold V_OVPS of 1.55V. To prevent this issue from
occurring, it is recommended to install resistors R_OPN1 and
R_OPN2, as shown in Figure 5. These resistors provide
voltage feedback from the regulator local output in the
absence of the GPU. These resistors should be in the range
of 20Ω to 100Ω.
10
FN6745.1
July 8, 2010