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PDF MAX8550 Data sheet ( Hoja de datos )
| Número de pieza | MAX8550 | |
| Descripción | (MAX8550 / MAX8551) Integrated DDR Power-Supply Solutions | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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www.DataSheet.co.kr
19-3173; Rev 2; 9/04
EVAALVUAAILTAIOBNLEKIT
Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
General Description
The MAX8550/MAX8551 integrate a synchronous-buck
PWM controller to generate VDDQ, a sourcing and sinking
LDO linear regulator to generate VTT, and a 10mA refer-
ence output buffer to generate VTTR. The buck controller
drives two external N-channel MOSFETs to generate out-
put voltages down to 0.7V from a 2V to 28V input with out-
put currents up to 15A. The LDO can sink or source up to
1.5A continuous and 3A peak current. Both the LDO out-
put and the 10mA reference buffer output can be made
to track the REFIN voltage. These features make the
MAX8550/MAX8551 ideally suited for DDR memory appli-
cations in desktops, notebooks, and graphic cards.
The PWM controller in the MAX8550/MAX8551 utilizes
Maxim’s proprietary Quick-PWM™ architecture with pro-
grammable switching frequencies of up to 600kHz. This
control scheme handles wide input/output voltage ratios
with ease and provides 100ns response to load tran-
sients while maintaining high efficiency and a relatively
constant switching frequency. The MAX8550 offers fully
programmable UVP/OVP and skip-mode options ideal in
portable applications. Skip mode allows for improved
efficiency at lighter loads. The MAX8551, which is tar-
geted towards desktop and graphic-card applications,
does not offer the pulse-skip feature.
The VTT and VTTR outputs track to within 1% of VREFIN / 2.
The high bandwidth of this LDO regulator allows excel-
lent transient response without the need for bulk capac-
itors, thus reducing cost and size.
The buck controller and LDO regulators are provided with
independent current limits. Adjustable lossless foldback
current limit for the buck regulator is achieved by monitor-
ing the drain-to-source voltage drop of the low-side MOS-
FET. Additionally, overvoltage and undervoltage
protection mechanisms are built in. Once the overcurrent
condition is removed, the regulator is allowed to enter
soft-start again. This helps minimize power dissipation
during a short-circuit condition. The MAX8550/MAX8551
allow flexible sequencing and standby power manage-
ment using the SHDNA, SHDNB, and STBY inputs.
Both the MAX8550 and MAX8551 are available in a
small 5mm × 5mm, 28-pin thin QFN package.
Applications
DDR I and DDR II Memory Power Supplies
Desktop Computers
Notebooks and Desknotes
Graphic Cards
Game Consoles
RAID
Networking
Buck Controller
Features
♦ Quick-PWM with 100ns Load-Step Response
♦ Up to 95% Efficiency
♦ 2V to 28V Input Voltage Range
♦ 1.8V/2.5V Fixed or 0.7V to 5.5V Adjustable Output
♦ Up to 600kHz Selectable Switching Frequency
♦ Programmable Current Limit with Foldback
Capability
♦ 1.7ms Digital Soft-Start and Independent
Shutdown
♦ Overvoltage/Undervoltage-Protection Option
♦ Power-Good Window Comparator
LDO Section
♦ Fully Integrated VTT and VTTR Capability
♦ VTT has ±3A Sourcing/Sinking Capability
♦ VTT and VTTR Outputs Track VREFIN / 2
♦ All-Ceramic Output-Capacitor Designs
♦ 1.0V to 2.8V Input Voltage Range
♦ Power-Good Window Comparator
Ordering Information
PART
TEMP RANGE
MAX8550ETI
-40°C to +85°C
MAX8550ETI+ -40°C to +85°C
MAX8551ETI
-40°C to +85°C
+Denotes lead-free package.
PIN-PACKAGE
28 5mm × 5mm TQFN
28 5mm × 5mm TQFN
28 5mm × 5mm TQFN
Pin Configuration
TOP VIEW
TON
OVP/UVP
(N.C. FOR
MAX8551)
REF
1
2
3
ILIM 4
POK1 5
POK2 6
STBY 7
MAX8550
MAX8551
21 DL
20 BST
19 LX
18 DH
17 VIN
16 OUT
15 FB
5mm x 5mm Thin QFN
Typical Operating Circuit appears at end of data sheet.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Datasheet pdf - http://www.DataSheet4U.net/
1 page  
www.DataSheet.co.kr
Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +15V, VDD = AVDD = VSHDNA = VSHDNB = VBST = VILIM = 5V, VOUT = VREFIN = VVTTI = 2.5V, UVP/OVP = STBY = FB = SKIP
= GND, PGND1 = PGND2 = LX = GND, TON = OPEN, VVTTS = VVTT, TA = -40°C to +85°C, unless otherwise noted. Typical values
are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
LINEAR REGULATORS (VTTR AND VTT)
VTTI Input Voltage Range
VTTI Supply Current
VVTTI
IVTTI
VTTI Shutdown Current
REFIN Input Impedance
REFIN Range
VREFIN
REFIN Lockout Threshold
Soft-Start Charge Current
VTT Internal MOSFET High-Side
On-Resistance
ISS
CONDITIONS
IVTT = IVTTR = 0
SHDNA = SHDNB = GND
VREFIN = 2.5V
VREFIN rising
Hysteresis
VSS = 0
IVTT = -100mA, VVTTI = 1.5V,
AVDD = 4.5V
MIN TYP MAX UNITS
1 2.8
<0.1
1
10
12 20 30
1 2.8
0.7 0.9
75
4
0.3
V
mA
µA
kΩ
V
V
mV
µA
Ω
VTT Internal MOSFET Low-Side
On-Resistance
IVTT = 100mA, AVDD = 4.5V
0.3 Ω
VTT Output Accuracy
(Referred to VREFIN / 2)
VREFIN = 1.5V or 2.5V, IVTT = 1mA
-1
+1 %
VTT Load Regulation
VREFIN = 2.5V, IVTT = 0 to ±1.5A
VREFIN = 1.5V, IVTT = 0 to ±1A
1
%
1
VTT Current Limit
VTT = 0 or VTTI
±3 ±5 ±6.5 A
VTTS Input Current
IVTTS VVTTS = 1.5V, VTT open
0.1 1
µA
VTTR Output Error
(Referred to VREFIN / 2)
VREFIN = 1.5V or 2.5V, IVTTR = 0 -1 +1 %
VTTR Current Limit
VVTTR = 0 or VVTTI
±23 ±40 ±60
mA
Note 1: Specifications to -40°C are guaranteed by design, not production tested.
Note 2: When the inductor is in continuous conduction, the output voltage has a DC regulation level higher than the error-compara-
tor threshold by 50% of the ripple. In discontinuous conduction, the output voltage has a DC regulation level higher than the
trip level by approximately 1.5% due to slope compensation.
Note 3: On-time and off-time specifications are measured from 50% point to 50% point at the DH pin with LX = GND, VBST = 5V,
and a 250pF capacitor connected from DH to LX. Actual in-circuit times may differ due to MOSFET switching speeds.
Note 4: Not applicable to the MAX8551.
_______________________________________________________________________________________ 5
Datasheet pdf - http://www.DataSheet4U.net/
5 Page 
www.DataSheet.co.kr
Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
IN
tOFF
TRIG MAX8550/
Q ONE-SHOT
MAX8551
TON
ON-TIME
COMPUTE
OUT
tON
TRIG
ONE-SHOT
Q
S
Q
R
BST
DH
LX
INTREF
1.16 x INTREF
S
Q
R
VDD
DL
PGND
OVP/UVP
(N.C. IN MAX8551)
SHDNA
BUCK ON/OFF
QUAD LEVEL
DECODE
OVP/UVP
LATCH
SHDNB
STBY
SHUTDOWN BIAS ON/OFF
DECODER
VTT ON/OFF VTTR ON/OFF
0.7 x INTREF
INTREF + 10%
20ms
TIMER
INTREF - 10%
POK1
N
FB
1.0V
LX
ZERO CROSSING
VDD - 1V
LX
VOUT = 1.8V
VOUT = 2.5V
DISCHARGE
LOGIC
FB
DECODE
INTREF
2V
REFERENCE
N
POK2
REFIN / 2 - 10%
REFIN / 2 + 10%
+0.4V
POWER-DOWN*
VTT ILIM
N
CURRENT
LIMITS
VTTR ILIM
10kΩ
10kΩ
REFIN / 2
VDD
N
VDD
N
VTTI
*POWER-DOWN
FORCES POK2 LOW
AND VTT, VTTR TO
HIGH IMPEDANCE.
REFIN / 2 - 10%
Figure 1. Functional Diagram
REFIN / 2 + 10%
SS
PGND2
ILIM
SKIP
(TP1 IN MAX8551
MUST BE CONNECTED TO GND)
OUT
AVDD
GND
REF
VTTS
REFIN
VTTI
VTT
PGND2
VTTR
______________________________________________________________________________________ 11
Datasheet pdf - http://www.DataSheet4U.net/
11 Page | ||
| Páginas | Total 29 Páginas | |
| PDF Descargar | [ Datasheet MAX8550.PDF ] | |
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