MAX8720ETX+ Maxim Integrated Products, MAX8720ETX+ Datasheet - Page 12

• Manufacturer Part Number: MAX8720ETX+
• Description: IC CNTRL VID STP DWN 36-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8720ETX+

• Applications: Controller, CPU GPU
• Voltage - Input: 2 ~ 28 V
• Number Of Outputs: 1
• Voltage - Output: 0.28 ~ 1.85 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 36-TQFN Exposed Pad
• Output Voltage: 0.275 V to 1.85 V
• Input Voltage: 2 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX8720 is a constant-on-time, quick-PWM con-
troller with 6-bit VID inputs to dynamically set the output
voltage from 0.275V to 1.85V. The MAX8720 standard
application circuit (Figure 1) generates a low-voltage
1.25V/15A output typical of low-power CPU and GPU
core supplies in a notebook computer. The input sup-
ply range is 7V to 24V. See Table 1 for component
selections and Table 2 for component manufacturers.
The MAX8720 requires an external 5V bias supply in
addition to the battery. Typically, this 5V bias supply is
the notebook’s 95%-efficient, 5V system supply.
Keeping the bias supply external to the IC improves
efficiency and eliminates the cost associated with the
5V linear regulator that would otherwise be needed to
supply the PWM circuit and gate drivers. If stand-alone
capability is needed, the 5V supply can be generated
with an external linear regulator.
Dynamically Adjustable 6-Bit VID
Step-Down Controller
12
Figure 1. MAX8720 Standard Application Circuit
______________________________________________________________________________________
+5V BIAS
VID0
VID1
VID2
VID3
VID4
VID5
PGOOD
5V Bias Supply (V
(6) 100kΩ
R2 TO R7
100kΩ
R8
Detailed Description
PWM
ON
SUSPEND
OPEN (300kHz)
4-LEVEL
INPUTS
SKIP
OFF
100kΩ
CC
R
1µF
C2
TIME
and V
V
AGND*
D0
D1
D2
D3
D4
D5
S0
S1
TON
PGOOD
SUS
TIME
SKIP
SHDN
CC
DD
MAX8720
10Ω
)
R1
*PGND
GNDS
ILIM
V
BST
FBS
REF
The 5V bias supply must provide V
and V
drawn is:
where I
and Q
sheet’s total gate-charge specification limits at V
V+ and V
source is a fixed 4.5V to 5.5V supply. If the 5V bias supply
is powered up prior to the battery supply, the enable sig-
nal (SHDN going from low to high) must be delayed until
the battery voltage is present to ensure startup.
The 2V reference is accurate to ±0.75% over tempera-
ture and load, making REF useful as a precision system
reference. Bypass REF to GND with a 0.22µF or greater
ceramic capacitor. The reference sources up to 100µA
and sinks 10µA to support external loads. Loading the
reference reduces the output voltages slightly, because
of the reference load regulation error.
DH
CC
DL
DD
V+
LX
FB
DD
R
100kΩ
G(LOW)
D
C
0.1µF
CC
I
ILIM1
BST
C
47pF
BST
BIAS
33.2kΩ
R
N
CC
DD
ILIM2
L
(gate-drive power), so the maximum current
is 800µA (typ), f
C
0.22µF
REF
can be connected together if the input power
V
V
= I
= 4mA to 40mA (typ)
CPU_SENSE
GND_SENSE
N
and Q
H
CC
D
*FOR THE MAX8720EEI, AGND AND PGND
+ f
REFER TO A SINGLE PIN DESIGNATED GND
L
C1
1µF
C
(2) 10µF
0.8µH
IN
SW
L1
CONNECT TO REMOTE-
SENSE POINTS
G(HIGH)
(Q
SW
G(LOW)
+5V BIAS
INPUT (V
7V TO 28V
is the switching frequency,
are the MOSFET data
OUTPUT
(V
C
(3) 470µF
IN
OUT
OUT
Reference (REF)
)
CC
+ Q
)
(PWM controller)
G(HIGH)
GS
)
= 5V.