MAX8770GTL+T Maxim Integrated Products, MAX8770GTL+T Datasheet - Page 36

• Manufacturer Part Number: MAX8770GTL+T
• Description: IC CTLR PS 2/1PH QUICK PWM 40QFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8770GTL+T

• Applications: Controller, Intel IMVP-6
• Voltage - Input: 4 ~ 26 V
• Number Of Outputs: 1
• Voltage - Output: 0.125 ~ 1.5 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PWM Controller for IMVP-6+ CPU Core Power Supplies
CONFIDENTIAL INFORMATION – RESTRICTED TO INTEL
inhibits switching until V
troller powers up the reference once the system
enables the controller, V
ven high. With the reference in regulation, the controller
ramps the output voltage to the 1.20V boot voltage at
1/8 the slew rate set by R
where dV
slew rate. The soft-start circuitry does not use a variable
current limit, so full output current is available immediate-
ly. CLKEN is pulled low approximately 60µs after the
MAX8770/MAX8771/MAX8772 reach the boot voltage. At
the same time, the MAX8770/MAX8771/MAX8772 slew
the output to the voltage set at the VID inputs at the pro-
grammed slew rate. PWRGD and PHASEGD become
high impedance approximately 5ms after CLKEN is
pulled low. The MAX8770/MAX8771/MAX8772 automati-
cally use forced-PWM operation during soft-start and
soft-shutdown, regardless of the DPRSLPVR and PSI
configuration.
For automatic startup, the battery voltage should be
present before V
the output into regulation without the battery-voltage
present, the fault latch trips. The controller remains shut
down until the fault latch is cleared by toggling SHDN
or cycling the V
If the V
assumes that there is not enough supply voltage to
make valid decisions. To protect the output from over-
voltage faults, the controller shuts down immediately
and forces a high-impedance output.
When SHDN goes low, the MAX8770/MAX8771/MAX8772
enter low-power shutdown mode. CLKEN is pulled high
and PWRGD is pulled low immediately, and the output
voltage ramps down at 1/8 the slew rate set by R
where dV
the slew rate. Slowly discharging the output capacitors
by slewing the output over a long period of time keeps
the average negative inductor current low (damped
response), thereby eliminating the negative output-volt-
age excursion that occurs when the controller dis-
charges the output quickly by permanently turning on
the low-side MOSFET (underdamped response). This
36
______________________________________________________________________________________
CC
TARGET
MAX8770/MAX8771/MAX8772 Dual-Phase, Quick-
TARGET
voltage drops below 4.25V, the controller
t
t
TRAN START
TRAN SHDN
CC
/dt = 12.5mV/µs x 71.5kΩ / R
CC
/dt = 12.5mV/µs x 71.5kΩ / R
(
(
power supply below 0.5V.
. If the controller attempts to bring
CC
CC
)
)
TIME
=
=
rises above 4.25V. The con-
(
above 4.25V and SHDN dri-
(
dV
dV
:
TARGET
TARGET
8
8
V
V
BOOT
OUT
/
/
dt
dt
)
)
Shutdown
TIME
TIME
TIME
is the
:
is
eliminates the need for the Schottky diode normally
connected between the output and ground to clamp
the negative output-voltage excursion. After the con-
troller reaches the zero target, the MAX8770/
MAX8771/MAX8772 shut down completely—the drivers
are disabled (DL1 and DL2 driven high)—the reference
turns off, and the supply currents drop to about 1µA
(max) 20µs.
When a fault condition—output UVLO or thermal shut-
down—activates the shutdown sequence, the protection
circuitry sets the fault latch to prevent the controller from
restarting. To clear the fault latch and reactivate the con-
troller, toggle SHDN or cycle V
The MAX8770/MAX8771/MAX8772 include a single-
quadrant multiplier used to determine the actual output
power based on the inductor current (sum of the differ-
ential CS inputs) and output voltage (CSNpm to GNDS,
when CSNpm = CSN12 for MAX8771, CSNpm = CSN2
for MAX8770/MAX8772). The buffered output of this
multiplier is connected to POUT and provides a voltage
relative to the output power dissipation:
where the power-monitor scale factor (K
ly 16.67mV. The power monitor allows the system to
accurately monitor the CPU’s power dissipation and
quickly predict if the system is about to overheat before
the significantly slower temperature sensor signals an
overtemperature alert.
The MAX8771 includes a phase-fault output that sig-
nals the system that one of the two phases either has a
fault condition or is not matched with the other.
Detection is done by identifying the need for a large on-
time difference between phases in order to achieve or
move towards current balance. PHASEGD is forced low
when V
PHASEGD is high impedance when the MAX8771 is set
to run in 1-phase operation (DPRSLPVR high, or PSI
low and DPRSLPVR low). On exit to the 2-phase mode,
PHASEGD is forced high impedance for 32 switching
cycles on DH2.
PHASEGD is low in shutdown. PHASEGD is forced high
impedance whenever the slew rate controller is active
(output voltage transitions).
Phase Fault (PHASEGD, MAX8771 Only)
CCI
V
PWR
is below 0.6xV
=
(
V
CSN
®
pm V
IMVP-6 LICENSEES
−
FB
Power Monitor (POUT)
GNDS
K
or above 1.4xV
CC
PWR
)(
power below 0.5V.
I
LOAD SENSE
R
PWR
FB
) is typical-
)
.