MAX8632ETI+ Maxim Integrated Products, MAX8632ETI+ Datasheet - Page 15

• Manufacturer Part Number: MAX8632ETI+
• Description: IC PWR SUPPLY DDR 28-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8632ETI+

• Applications: Controller, DDR
• Voltage - Input: 2 ~ 28 V
• Number Of Outputs: 1
• Voltage - Output: 1.8V, 2.5V, 0.7 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Output Voltage: 1.8 V or 2.5 V or 0.7 V to 5.5 V
• Output Current: 15 A
• Input Voltage: 2 V to 28 V
• Supply Current: 25 uA
• Switching Frequency: 600 KHz
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 3. Adjustable Current-Limit Threshold
Figure 4. Valley Current-Limit Threshold
when OVP and shutdown discharge are disabled
(OVP/UVP = REF or GND) or forcing DL high when OVP
and shutdown discharge are enabled (OVP/UVP =
AV
for OVP/UVP and shutdown settings. When AV
above 4.25V, the controller activates the buck regulator
and initializes the internal soft-start.
The buck regulator’s internal soft-start allows a gradual
increase of the current-limit level during startup to
DD
or OPEN). See Table 3 for a detailed truth table
0
Integrated DDR Power-Supply Solution for
Desktops, Notebooks, and Graphic Cards
______________________________________________________________________________________
(SEE FIGURE 1)
CONTROLLER
TO PWM
TIME
I
I
LIM(VAL) =
LOAD(MAX)
(
1 -
LX
LIR
2
)
x
1.0V
I
I
I
PEAK
LOAD
LIMIT
I
LOAD
DD
rises
reduce the input surge currents. The MAX8632 divides
the soft-start period into five phases. During the first
phase, the controller limits the current limit to only 20%
of the full current limit. If the output does not reach reg-
ulation within 425µs, soft-start enters the second phase,
and the current limit is increased by another 20%. This
process repeats until the maximum current limit is
reached, after 1.7ms, or when the output reaches the
nominal regulation voltage, whichever occurs first.
Adding a capacitor in parallel with the external ILIM
resistors creates a continuously adjustable analog soft-
start function for the buck regulator’s output.
Soft-start in the LDO section can be realized by con-
necting a capacitor between the SS pin and ground.
When VTT is turned off or placed in standby mode, or
during thermal shutdown of the LDOs, the SS capacitor
is discharged. When VTT is turned on or when the ther-
mal limit is removed, an internal 4µA (typ) current
charges the SS capacitor. The resulting ramp voltage
on SS linearly increases the current-limit comparator
threshold to the VTT output, until full current limit is
attained when SS reaches approximately 1.6V. This
lowering of the current limit during startup limits the ini-
tial inrush current peaks, particularly when driving
capacitors. Choose the value of the SS capacitor
appropriately to set the soft-start time window. Leave
SS floating to disable the soft-start feature.
POK1 is an open-drain output for a window comparator
that continuously monitors V
MAX8632
V
DD
- 1V
ILIM
REF
R
R
A
B
OUT
C
C
. POK1 is actively held
Power-OK (POK1)
ILIM
REF
15