MAX17528GTJ+ Maxim Integrated Products, MAX17528GTJ+ Datasheet - Page 33

• 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

Table 3. Operating Mode Truth Table
When SHDN goes low, the MAX17528 enters low-
power shutdown mode. PWRGD is pulled low immedi-
ately, and the output voltage ramps down at 1/8 the
slew rate set by R
where dV
nominal slew rate. Slowly discharging the output capaci-
tors by slewing the output over a long period of time
keeps the average negative inductor current low
(damped response), thereby eliminating the negative
output-voltage excursion that occurs when the controller
discharges the output quickly by permanently turning on
the low-side MOSFET (underdamped response). This
eliminates the need for the Schottky diode connected
between the output and ground to clamp the negative
output-voltage excursion. After the controller reaches
the zero target, the MAX17528 shuts down completely—
Falling
Rising
GND
High
High
High
High
TARGET
High
Low
X
X
X
X
X
t
TRAN SHDN
/dt = 12.5mV/µs x 71.5kΩ/R
TIME
(
______________________________________________________________________________________
SKIP
High
High
Low
X
X
X
X
:
)
=
DISABLED
Pulse skipping
1/8 R
rate
Forced-PWM
nominal R
slew rate
Pulse-skipping
nominal R
slew rate
Pulse-skipping
1/2 R
rate
Forced-PWM
1/8 R
rate
DISABLED
(
dV
TIME
TIME
TIME
TARGET
8
V
OUT
TIME
TIME
slew
slew
slew
Intel IMVP-6.5/GMCH Controllers
/
dt
)
Shutdown
LOW-POWER SHUTDOWN. DL forced low, and the controller is disabled. The
supply current drops below 30µA.
STARTUP. When SHDN is pulled high, the MAX17528 begins the startup
sequence after the internal circuitry powers up. The MAX17528 enables the
PWM controller and ramps the output voltage up to the startup voltage. See
Figures 9 and 10.
FULL POWER. The no-load output voltage is determined by the selected VID
DAC code (Table 2).
LOW-POWER MODE (NOMINAL TRANSITION). The no-load output voltage is
determined by the selected VID DAC code (Table 2). When SKIP is pulled high,
the controller immediately enters pulse-skipping operation, allowing automatic
PWM/PFM switchover under light loads. The PWRGD and CLKEN upper
thresholds are blanked during the transition.
LOW-POWER MODE (SLOW TRANSITION). The no-load output voltage is
determined by the selected VID DAC code (Table 2). When SKIP is pulled high,
the MAX17528 enters pulse-skipping operation, allowing automatic PWM/PFM
switchover under light loads. The PWRGD and CLKEN thresholds are blanked
during the transition.
SHUTDOWN. When SHDN is pulled low, the MAX17528 immediately pulls
PWRGD low, CLKEN becomes high impedance, and the output voltage is
ramped down to ground. Once the output reaches zero, the controller enters the
low-power shutdown state. See Figures 9 and 10.
FAULT MODE. The fault latch has been set by the MAX17528 UVP fault, R
open fault, or thermal-shutdown protection. The controller remains in FAULT
mode until V
TIME
is the
CC
power is cycled or SHDN toggled.
the drivers are disabled (DL and DH are pulled low)—
the internal reference turns off, and the supply currents
drop to about 30µA (max).
When an output undervoltage fault condition activates
the shutdown sequence, the protection circuitry sets the
UVP fault latch to prevent the controller from restarting.
To clear the fault latch and reactivate the controller,
toggle SHDN or cycle V
The MAX17528 includes a unidirectional transconduc-
tance amplifier that sources current proportional to the
positive current-sense voltage. The IMON output cur-
rent is defined by:
where G
unidirectional (sources current out of IMON only) for
positive current-sense values. For negative current-
sense voltages, the IMON current is zero.
OPERATING MODE
1-Phase Quick-PWM
m(IMON)
I
IMON
= G
= 5mS (typ) and the IMON current is
m(IMON)
CC
Current Monitor (IMON)
power below 0.5V.
x (V
CSP
- V
CSN
)
TON
33