MAX8576EUB+ ,3V to 28V Input, Low-Cost, Hysteretic Synchronous Step-Down ControllersELECTRICAL CHARACTERISTICS(V = 12V (MAX8576/MAX8577 only), 4.7µF capacitor from VL (MAX8576/MAX8577 ..
MAX8576EUB+T ,3V to 28V Input, Low-Cost, Hysteretic Synchronous Step-Down ControllersFeaturesThe MAX8576–MAX8579 synchronous PWM buck con-♦ 3V to 28V Supply Voltage Rangetrollers use a ..
MAX8577EUB ,3V to 28V Input, Low-Cost, Hysteretic Synchronous Step-Down ControllersELECTRICAL CHARACTERISTICS (continued)(V = 12V (MAX8576/MAX8577 only), 4.7µF capacitor from VL (MAX ..
MAX8577EUB+ ,3V to 28V Input, Low-Cost, Hysteretic Synchronous Step-Down ControllersFeaturesThe MAX8576–MAX8579 synchronous PWM buck con-♦ 3V to 28V Supply Voltage Rangetrollers use a ..
MAX8578EUB ,3V to 28V Input, Low-Cost, Hysteretic Synchronous Step-Down ControllersELECTRICAL CHARACTERISTICS(V = 12V (MAX8576/MAX8577 only), 4.7µF capacitor from VL (MAX8576/MAX8577 ..
MAX8578EUB ,3V to 28V Input, Low-Cost, Hysteretic Synchronous Step-Down ControllersMAX8576–MAX857919-3289; Rev 1; 6/053V to 28V Input, Low-Cost, HystereticSynchronous Step-Down Contr ..
MB84256A-10LLP , CMOS 256K-BIT LOW POWER SRAM
MB84256A-10LPF , CMOS 256K-BIT LOW POWER SRAM
MB84VD21183EM-70PBS , Stacked MCP (Multi-Chip Package) FLASH MEMORY & SRAM CMOS
MB84VD21194EM-70PBS , Stacked MCP (Multi-Chip Package) FLASH MEMORY & SRAM CMOS
MB84VD22181FM-70PBS , 32M (X16) FLASH MEMORY & 4M (X16) STATIC RAM
MB84VD22182EE-90 ,32M (x 8/x16) FLASH MEMORY & 4M (x 8/x16) STATIC RAMFUJITSU SEMICONDUCTORDS05-50204-2EDATA SHEETStacked MCP (Multi-Chip Package) FLASH MEMORY & SRAMCMO ..
MAX8576EUB-MAX8576EUB+-MAX8576EUB+T-MAX8577EUB-MAX8577EUB+-MAX8578EUB-MAX8578EUB+-MAX8578EUB+T-MAX8579EUB+
3V to 28V Input, Low-Cost, Hysteretic Synchronous Step-Down Controllers
General DescriptionThe MAX8576–MAX8579 synchronous PWM buck con-
trollers use a hysteretic voltage-mode control algorithm
to achieve a fast transient response without requiring
loop compensation. The MAX8576/MAX8577 contain an
internal LDO regulator allowing the controllers to func-
tion from only one 3V to 28V input supply. The
MAX8578/MAX8579 do not contain the internal LDO
and require a separate supply to power the IC when the
input supply is higher than 5.5V. The MAX8576–
MAX8579 output voltages are adjustable from 0.6V to
0.9 x VINat loads up to 15A.
Nominal switching frequency is programmable over the
200kHz to 500kHz range. High-side MOSFET sensing is
used for adjustable hiccup current-limit and short-cir-
cuit protection. The MAX8576/MAX8578 can start up
into a precharged output without pulling the output volt-
age down. The MAX8577/MAX8579 have startup output
overvoltage protection (OVP), and will pull down a
precharged output.
ApplicationsMotherboard Power Supplies
AGP and PCI-Express Power Supplies
Graphic-Card Power Supplies
Set-Top Boxes
Point-of-Load Power Supplies
Features3V to 28V Supply Voltage Range1.2% Accurate Over TemperatureAdjustable Output Voltage Down to 0.6V200kHz to 500kHz Switching FrequencyAdjustable Temperature-Compensated Hiccup
Current LimitLossless Peak Current SensingMonotonic Startup into Prebias Output
(MAX8576/MAX8578)Startup Overvoltage Protection
(MAX8577/MAX8579)Enable/ShutdownAdjustable Soft-Start
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down ControllersOCSETGND
MAX8576
MAX8577
BSTDL
INPUT
UP TO 28V
OUTPUT
0.6V TO 0.9 x VIN
ypical Operating Circuit19-3289; Rev 1; 6/05
EVALUATION KIT
AVAILABLE
Ordering InformationPART TEMP RANGE PIN-PACKAGE
MAX8576EUB-40°C to +85°C10 µMAX®
MAX8577EUB-40°C to +85°C10 µMAX
MAX8578EUB-40°C to +85°C10 µMAX
MAX8579EUB-40°C to +85°C10 µMAX
Pin Configurations appear at end of data sheet.µMAX is a registered trademark of Maxim Integrated Products, Inc.
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down Controllers
ABSOLUTE MAXIMUM RATINGSStresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN to GND (MAX8576/MAX8577)...........................-0.3V to +30V
VL to GND (MAX8576/MAX8577).............................-0.3V to +6V
IN to VL (MAX8576/MAX8577)...............................-0.3V to +30V
VCCto GND (MAX8578/MAX8579)..........................-0.3V to +6V
SS to GND (MAX8576/MAX8577)...............-0.3V to (VVL+ 0.3)V
SS to GND (MAX8578/MAX8579)...............-0.3V to (VCC+ 0.3)V
DL to GND (MAX8576/MAX8577)...............-0.3V to (VVL+ 0.3)V
DL to GND (MAX8578/MAX8579)..............-0.3V to (VCC+ 0.3)V
BST to GND............................................................-0.3V to +36V
BST to LX..................................................................-0.3V to +6V
LX to GND.....................-1V (-2.5V for <50ns Transient) to +30V
DH to LX..................................................-0.3V to +(VBST+ 0.3)V
FB to GND................................................................-0.3V to +6V
EN to GND (MAX8578/MAX8679EUB).....................-0.3V to +6V
OCSET to GND (MAX8576/MAX8677)........-0.3V to (VIN+ 0.3)V
OCSET to GND (MAX8578/MAX8679)...................-0.3V to +30V
OCSET to LX (MAX8576/MAX8677)............-0.6V to (VIN+ 0.3)V
OCSET to LX (MAX8578/MAX8679).......................-0.6V to +30V
DH and DL Continuous Current ............................±250mA RMS
Continuous Power Dissipation (TA= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C)...........444mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................+300°C
ELECTRICAL CHARACTERISTICS(VIN= 12V (MAX8576/MAX8577 only), 4.7µF capacitor from VL (MAX8576/MAX8577 only) or VCC(MAX8578/MAX8579 only) to GND;
VCC= VEN= 5V (MAX8578/MAX8579 only); 0.01µF capacitor from SS to GND; VFB= 0.65V; VBST= 5V; VLX= VGND= 0V; VOCSET=
11.5V; DH = unconnected; DL = unconnected; TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERCONDITIONSMINTYPMAXUNITS
SUPPLY VOLTAGESMAX8576/MAX85775.528.0IN Supply VoltageIN = VL (MAX8576/MAX8577)3.05.5V
VCC Input VoltageMAX8576/MAX85773.05.5V
VL Output VoltageIVL = 10mA (MAX8576/MAX8577)4.755.05.25V
VL Maximum Output CurrentMAX8576/MAX857720mA
Rising2.752.82.90
Falling2.42.452.5VVL or VCC Undervoltage Lockout
(UVLO)Hysteresis350mV
VIN = 12V0.62
VIN = VVL = 5V1.13No switching, VFB = 0.65V
(MAX8576/MAX8577)VIN = VVL = 3.3V0.62
VCC = 5V0.62
Supply Current
VEN = 0V or VFB = 0.65V, no
switching (MAX8578/MAX8579)VCC = 3.3V0.62
REGULATOROutput Regulation AccuracyVFB peak0.5930.60.607V
Output Regulation Hysteresis(Note 1)12.52028.0mV
FB falling to DL falling50FB Propagation DelayFB rising to DH falling70ns
Overvoltage-Protection (OVP)
Threshold0.700.750.80V
TA = +85°C60High-Side Current-Sense
Program Current (Note 2)TA = +25°C42.55057.5µA
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down Controllers
ELECTRICAL CHARACTERISTICS (continued)(VIN= 12V (MAX8576/MAX8577 only), 4.7µF capacitor from VL (MAX8576/MAX8577 only) or VCC(MAX8578/MAX8579 only) to GND;
VCC= VEN= 5V (MAX8578/MAX8579 only); 0.01µF capacitor from SS to GND; VFB= 0.65V; VBST= 5V; VLX= VGND= 0V; VOCSET=
11.5V; DH = unconnected; DL = unconnected; TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERCONDITIONSMINTYPMAXUNITSHigh-Side Current-Sense
Overcurrent Trip Adjustment
Range
VIN - VOCSET0.050.40V
Soft-Start Internal Resistance4580125kΩ
Fault Hiccup Internal SS Pulldown
CurrentVLX < VOCSET and VFB < VSS250nA
DRIVER SPECIFICATIONSSourcing current2.64.0DH Driver ResistanceSinking current1.93.0Ω
Sourcing current2.64.0DL Driver ResistanceSinking current1.12.0Ω
Dead TimeDH low to DL high and DL low to DH high
(adaptive)40ns
DH Minimum On-Time140245ns
Normal operation120220DL Minimum On-TimeCurrent fault580ns
BST CurrentVBST - VLX = 5.5V, VLX = 28V, VFB < VSS1.65mA
Input Voltage LowVCC = 3V (MAX8578/MAX8579)0.7V
Input Voltage HighVCC = 5.5V (MAX8578/MAX8579)1.5V
THERMAL SHUTDOWNThermal ShutdownRising temperature, hysteresis = 20°C (typ)+160°C
ELECTRICAL CHARACTERISTICS(VIN= 12V (MAX8576/MAX8577 only), 4.7µF capacitor from VL (MAX8576/MAX8577 only) or VCC(MAX8578/MAX8579 only) to GND;
VCC= VEN= 5V (MAX8578/MAX8579 only); 0.01µF capacitor from SS to GND; VFB= 0.65V; VBST= 5V; VLX= VGND= 0V; VOCSET=
11.5V; DH = unconnected; DL = unconnected; TA
= -40°C to +85°C, unless otherwise noted. Note 3)
PARAMETERCONDITIONSMINTYPMAXUNITS
SUPPLY VOLTAGESMAX8576/MAX85775.528.0IN Supply VoltageIN = VL, MAX8576/MAX85773.05.5V
VCC Input VoltageMAX8576/MAX85773.05.5V
VL Output VoltageIVL = 10mA, MAX8576/MAX85774.755.25V
VL Maximum Output CurrentMAX8576/MAX857720mA
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down Controllers
Note 1:Guaranteed by design.
Note 2:This current linearly compensates for the MOSFET temperature coefficient.
Note 3:Specifications to -40°C are guaranteed by design and not production tested.
ELECTRICAL CHARACTERISTICS (continued)(VIN= 12V (MAX8576/MAX8577 only), 4.7µF capacitor from VL (MAX8576/MAX8577 only) or VCC(MAX8578/MAX8579 only) to GND;
VCC= VEN= 5V (MAX8578/MAX8579 only); 0.01µF capacitor from SS to GND; VFB= 0.65V; VBST= 5V; VLX= VGND= 0V; VOCSET=
11.5V; DH = unconnected; DL = unconnected; TA
= -40°C to +85°C, unless otherwise noted. Note 3)
PARAMETERCONDITIONSMINTYPMAXUNITSRising2.752.90VL or VCC Undervoltage Lockout
(UVLO)Falling2.402.55V
VIN = 12V2
VIN = VVL = 5V3.5No switching, VFB = 0.65V
(MAX8576/MAX8577)
VIN = VVL = 3.3V2
VCC = 5V2
Supply Current
VEN = 0V or VFB = 0.65V, no
switching (MAX8578/MAX8579)VCC = 3.3V2
REGULATOROutput Regulation AccuracyVFB peak0.5910.607V
Overvoltage-Protection (OVP)
Threshold0.700.80V
High-Side Current-Sense Over-
Current Trip Adjustment RangeVIN - VOCSET0.050.40V
DRIVER SPECIFICATIONSSourcing current4DH Driver ResistanceSinking current3.0Ω
Sourcing current4.0DL Driver ResistanceSinking current2.0Ω
DH Minimum On-Time245ns
DL Minimum On-TimeNormal operation220ns
Input Voltage LowVCC = 3V, MAX8578/MAX85790.7V
Input Voltage HighVCC = 5.5V, MAX8578/MAX85791.5V
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down Controllers
EFFICIENCY vs. LOAD CURRENT
(CIRCUIT OF FIGURE 2)MAX8576-79 toc01
LOAD CURRENT (A)
EFFICIENCY (%)1
VOUT = 3.3VVOUT = 2.5V
VOUT = 1.8VVOUT = 1.5V
VIN = 12V
EFFICIENCY vs. LOAD CURRENT
(CIRCUIT OF FIGURE 3)MAX8576-79 toc02
LOAD CURRENT (A)
EFFICIENCY (%)
VOUT = 3.3V
VOUT = 2.5V
VOUT = 1.8V
VOUT = 1.5V
VIN = 12V
LOAD REGULATION
(CIRCUIT OF FIGURE 2)MAX8576-79 toc03
LOAD CURRENT (A)
OUTPUT VOLTAGE (V)5
LINE REGULATION
(CIRCUIT OF FIGURE 2)
MAX8576-79 toc04
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)1510
0A LOAD
15A LOAD
LINE REGULATION
(CIRCUIT OF FIGURE 3)MAX8576-79 toc05
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)1510
NO LOAD
5A LOAD1.76
SWITCHING FREQUENCY vs. INPUT
VOLTAGE (CIRCUIT OF FIGURE 3)MAX8576-79 toc06
INPUT VOLTAGE (V)
SWITCHING FREQUENCY (kHz)1510
LOAD TRANSIENT
(CIRCUIT OF FIGURE 2)
MAX8576-79 toc07
40μs/div
IOUT
VOUT50mV/div
AC-COUPLED
12A
LOAD TRANSIENT
(CIRCUIT OF FIGURE 3)MAX8576-79 toc08
40μs/div
IOUT
VOUT50mV/div
AC-COUPLED
2.5A
Typical Operating Characteristics(TA= +25°C, unless otherwise noted.)
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down Controllers
Typical Operating Characteristics (continued)( TA= +25°C, unless otherwise noted.)
POWER-DOWN
(CIRCUIT OF FIGURE 2, MAX8576)MAX8576-79 toc13
4ms/div
VIN
VOUT
ILX
5V/div
1V/div
10A/div
STARTUP AND SHUTDOWN
(CIRCUIT OF FIGURE 3)MAX8576-79 toc14
400μs/div
VEN
VDL
VOUT
ILX
2V/div
10V/div
1V/div
5A/div
POWER-DOWN VCC
(CIRCUIT OF FIGURE 3)MAX8576-79 toc11
400μs/div
VIN
VCC
VOUT
ILX
10V/div
5V/div
1V/div
5A/div
POWER-UP
(CIRCUIT OF FIGURE 2)MAX8576-79 toc12
1ms/div
VIN
VOUT
ILX
10V/div
1V/div
10A/div
POWER-UP VIN
(CIRCUIT OF FIGURE 3)MAX8576-79 toc09
400μs/div
VIN
VCC
VOUT
ILX
10V/div
5V/div
1V/div
5A/div
POWER-UP VCC
(CIRCUIT OF FIGURE 3)MAX8576-79 toc10
400μs/div
VIN
VCC
VOUT
ILX
10V/div
5V/div
1V/div
5A/div
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down Controllers
Typical Operating Characteristics (continued)( TA= +25°C, unless otherwise noted.)
OUTPUT OVERVOLTAGE PROTECTION
(CIRCUIT OF FIGURE 2)MAX8576-79 toc19
200μs/div
VDH
VOUT
VDL
VFB
20V/div
5V/div
0.5V/div
1V/div
NONMONOTONIC OUTPUT-VOLTAGE RISE
(CIRCUIT OF FIGURE 2, MAX8577)MAX8576-79 toc17
1ms/div
VIN
VLX
VOUT
VDL
10V/div
1.5V
0.5V/div
20V/div
5V/div
SHORT CIRCUIT AND RECOVERY
(CIRCUIT OF FIGURE 2)MAX8576-79 toc18
10ms/div
VIN
IOUT
IIN
VOUT
10V/div
2A/div
10A/div
2V/div
STARTUP AND SHUTDOWN
(CIRCUIT OF FIGURE 2)MAX8576-79 toc15
4ms/div
VGS(Q3)
VSS
VOUT
ILX
10V/div
0.5V/div
2V/div
10A/div
MONOTONIC OUTPUT-VOLTAGE RISE
(CIRCUIT OF FIGURE 2, MAX8576)MAX8576-79 toc16
1ms/div
VIN
VLX
VOUT
VDL
10V/div
1.5V
0.5V/div
20V/div
5V/div
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down Controllers
PIN
MAX8576/
MAX8577
MAX8578/
MAX8579
NAMEFUNCTIONFBFeedback Input. Regulates at VFB = 0.59V. Connect FB to a resistor-divider to set the output
voltage. See the Setting the Output Voltage section.S S oft- S tar t. U se an exter nal cap aci tor ( C SS) to ad j ust the soft- star t ti m e. An i nter nal 80kΩ r esi stor g i ves
ap p r oxi m atel y 4m s soft- star t ti m e for a 0.01µF exter nal cap aci tor . An i nter nal 250nA cur r ent si nk i n
hi ccup m od e g i ves ap p r oxi m atel y 10% d uty cycl e d ur i ng faul t cond i ti ons.VLInternal 5V Linear-Regulator Output. Bypass with a 4.7µF or larger ceramic capacitor. Must be
connected to IN for operation from a 3.3V to 5.5V input.VCCSupply Input (3V to 5.5V). Bypass with a 4.7µF or larger ceramic capacitor to GND.4GNDGround5DLLow-Side Gate-Drive Output. Drives the synchronous-rectifier MOSFET.6BST
Boost-Capacitor Connection for High-Side Gate-Drive Output. Connect a 0.1µF ceramic
capacitor from BST to LX and a Schottky or switching diode and a 4.7Ω series resistor from
BST to VL (MAX8576/MAX8577) or VCC (MAX8578/MAX8579). See Figure 4.7LXExternal Inductor Connection. Connect LX to the junctions of the MOSFETs and inductor.8DHHigh-Side Gate-Drive Output. Drives the high-side MOSFET.INSupply Voltage Input of the Internal Linear Regulator (3V to 28V). Connect to VL for operation
from 3V to 5.5V input. Connect a 0.47µF or larger ceramic capacitor from IN to GND.ENEnable Input. A logic low on EN shuts down the converter and discharges the soft-start
capacitor. Drive high or connect to VCC for normal operation.10OCSET
Overcurrent-Limit Set. Programs the high-side peak current-limit threshold by setting the
maximum-allowed VDS voltage drop across the high-side MOSFET. Connect a resistor from IN
to OCSET; an internal 50µA current sink sets the maximum voltage drop relative to VIN. See the
Setting the Current Limit section.
Pin Description
MAX8576–MAX8579
3V to 28V Input, Low-Cost, Hysteretic
Synchronous Step-Down ControllersFigure 1. Functional Diagram
0.75V
0.05V
OVP
FAULT
VCC
REFOK
VLOK
GND
OCSET
MAX8578/
MAX8579
RAMP
LOGIC
DRIVERS
GND
VL REG
POK
REF
DHI
DLI
MAX8576–MAX8579
BST
MAX8578
MAX8579
MAX8576
MAX8577
