MAX8550ETI+ Maxim Integrated Products, MAX8550ETI+ Datasheet - Page 10

• Manufacturer Part Number: MAX8550ETI+
• Description: IC PWR SUP DDR INTEG 28TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8550ETI+

• Applications: Controller, DDR
• Voltage - Input: 2 ~ 28 V
• Number Of Outputs: 2
• 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: 0.7 V to 5.5 V, 1.8 V, 2.5 V
• Output Current: 20 A
• 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

Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
10
PIN
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
______________________________________________________________________________________
(MAX8550)
(MAX8551)
SHDNA
SHDNB
PGND2
PGND1
NAME
REFIN
AV
GND
OUT
SKIP
VTTI
BST
V
VTT
TP1
V
DH
FB
LX
DL
DD
IN
DD
Power Ground for VTT and VTTR. Connect PGND2 externally to the underside of the exposed pad.
Termination Power-Supply Output. Connect VTT to VTTS to regulate to V
Power-Supply Input Voltage for VTT and VTTR. Normally connected to the output of the buck regulator
for DDR application.
External Reference Input. This is used to regulate the VTT and VTTR outputs to V
Feedback Input for Buck Output. Connect to AV
output. For an adjustable output (0.7V to 5.5V), connect FB to a resistive divider from the output
voltage. FB regulates to +0.7V.
Output-Voltage Sense Connection. Connect to the positive terminal of the buck output filter capacitor.
OUT senses the output voltage to determine the on-time for the high-side switching MOSFET (Q1 in the
Typical Applications Circuit). OUT also serves as the buck output’s feedback input in fixed-output
modes. When discharge mode is enabled by OVP/UVP, the output capacitor is discharged through an
internal 10Ω resistor connected between OUT and GND.
Input-Voltage Sense Connection. Connect to input power source. V
time one-shot timer. IN voltage range is from 2V to 28V.
High-Side Gate-Driver Output. Swings from LX to BST. DH is low when in shutdown or UVLO.
External Inductor Connection. Connect LX to the input side of the inductor. LX is used for both current
limit and the return supply of the DH driver.
Boost Flying-Capacitor Connection. Connect to an external capacitor and diode according to the
Typical Applications Circuit (Figure 8). See the Boost-Supply Diode and Capacitor Selection section.
Synchronous-Rectifier Gate-Driver Output. Swings from PGND to V
Supply Input for the DL Gate Drive. Connect to the +4.5V to +5.5V system supply voltage. Bypass to
PGND1 with a 1µF (min) ceramic capacitor.
Power Ground for Buck Controller. Connect PGND1 externally to the underside of the exposed pad.
Analog Ground for Both Buck and LDO. Connect GND externally to the underside of the exposed pad.
Pulse-Skipping Control Input. Connect to AV
enable pulse-skipping operation.
In the MAX8551, this pin is a test pin and must be connected to GND (pin 24).
Analog Supply Input for Both Buck and LDO. Connect to the +4.5V to +5.5V system supply voltage
with a series 10Ω resistor. Bypass to GND with a 1µF or greater ceramic capacitor.
Shutdown Control Input A. Use to control buck output. A rising edge on SHDNA clears the overvoltage
and undervoltage-protection fault latches (see Tables 2 and 3). Connect to AV
Shutdown Control Input B. Use to control VTT and VTTR outputs. Both VTTR and VTT are high
impedence in shutdown (see Table 2).
DD
FUNCTION
for low-noise, forced-PWM mode. Connect to GND to
DD
for a +1.8V fixed output or to GND for a +2.5V fixed
Pin Description (continued)
DD
IN
.
is used only to set the PWM’s on-
REFIN
/ 2.
DD
REFIN
for normal operation.
/ 2.