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MAX1638EAG

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
General Description
The MAX1638 is an ultra-high-performance, step-down
DC-DC controller for CPU power in high-end computer
systems. Designed for demanding applications in which
output voltage precision and good transient response are
critical for proper operation, it delivers over 35A from 1.3V
to 3.5V with ±1% total accuracy from a +5V ±10% supply.
Excellent dynamic response corrects output transients
caused by the latest dynamically clocked CPUs. This
controller achieves over 90% efficiency by using synchro-
nous rectification. Flying-capacitor bootstrap circuitry
drives inexpensive, external N-channel MOSFETs.
The switching frequency is pin-selectable for 300kHz,
600kHz, or 1MHz. High switching frequencies allow the
use of a small surface-mount inductor and decrease out-
put filter capacitor requirements, reducing board area
and system cost.
The MAX1638 is available in 24-pin SSOP and QSOP
(future package) packages, and offers additional fea-
tures such as a digitally programmable output;
adjustable transient response; and selectable 0.5%, 1%,
or 2% AC load regulation. Fast recovery from load tran-
sients is ensured by a GlitchCatcher™ current-boost cir-
cuit that eliminates delays caused by the buck inductor.
Output overvoltage protection is enforced by a crowbar
circuit that turns on the low-side MOSFET with 100%
duty factor when the output is 200mV above the normal
regulation point. Other features include internal digital
soft-start, a power-good output, and a 3.5V ±1% refer-
ence output.
________________________Applications
Pentium Pro™, Pentium II™, PowerPC™, Alpha™,
and K6™ Systems
Workstations
Desktop Computers
LAN Servers
GTL Bus Termination
____________________________Features
♦ Better than ±1% Output Accuracy Over
Line and Load
♦ Greater than 90% Efficiency Using N-Channel
MOSFETs
♦ Pin-Selected High Switching Frequency (300kHz,
600kHz, or 1MHz)
♦ Over 35A Output Current
♦ Digitally Programmable Output from 1.3V to 3.5V
♦ Current-Mode Control for Fast Transient
Response and Cycle-by-Cycle Current-Limit
Protection
♦ Short-Circuit Protection with Foldback Current
Limiting
♦ Glitch-Catcher Circuit for Fast Load-Transient
Response
♦ Crowbar Overvoltage Protection
♦ Power-Good (PWROK) Output
♦ Digital Soft-Start
♦ High-Current (2A) Drive Outputs
♦ Complies with Intel VRM 8.2 Specification
MAX1638
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
________________________________________________________________ Maxim Integrated Products 1
19-1313; Rev 1; 8/05
PART
MAX1638EAG
MAX1638EAG+ -40°C to +85°C
-40°C to +85°C
TEMP RANGE PIN-PACKAGE
24 SSOP
24 QSOP
Ordering Information
Typical Operating Circuit
Pin Configuration appears at end of data sheet.
Pentium Pro and Pentium II are trademarks of Intel Corp.
PowerPC is a trademark of IBM Corp.
Alpha is a trademark of Digital Equipment Corp.
K6 is a trademark of Advanced Micro Devices.
GlitchCatcher is a trademark of Maxim Integrated Products.
V
CC
AGND
REF
LG
FREQ
CC1
CC2
DL
PWROK
D0
LX
BST
DH
PGND
TO V
DD
CSH
OUTPUT
1.3V TO 4.5V
INPUT
+5V
V
DD
CSL
FB
MAX1638
D1
D2
D3
D4
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.
EVALUATION KIT
AVAILABLE
+Denotes lead-free package.
MAX1638
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
DD
= V
CC
= D4 = +5V, PGND = AGND = D0–D3 = 0V, FREQ = REF, T
A
= 0°C to +85°C, unless otherwise noted.)
Stresses 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.
V
DD
, V
CC
, PWROK to AGND ......................................-0.3V to 6V
PGND to AGND ..................................................................±0.3V
CSH, CSL to AGND....................................-0.3V to (V
CC
+ 0.3V)
NDRV, PDRV, DL to PGND.........................-0.3V to (V
DD
+ 0.3V)
REF, CC1, CC2, LG, D0–D4, FREQ,
FB to AGND.............................................-0.3V to (V
CC
+ 0.3V)
BST to PGND ............................................................-0.3V to 12V
BST to LX ....................................................................-0.3V to 6V
DH to LX.............................................(LX - 0.3V) to (BST + 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
QSOP (derate 8.70mW/°C above +70°C).....................696mW
QSOP
θ
JC
..................................................................40°C/W
SSOP (derate 8.00mW/°C above +70°C) .....................640mW
SSOP θ
JC
..................................................................45°C/W
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
FREQ = AGND
FREQ = REF
V
CC
= V
DD
FREQ = V
CC
PWROK = 5.5V
Over line and load
(Note 1)
I
SINK
= 2mA, V
CC
= 4.5V
Falling FB, 1% hysteresis with respect to V
REF
Rising FB, 1% hysteresis with respect to V
REF
CSH - CSL =
0mV to 80mV
0µA < I
REF
< 100µA
No load
V
CC
= V
DD
= 5.5V, FB forced 200mV above
regulation point, operating or standby mode
V
CC
rising edge, 1% hysteresis
V
REF
= 0V
Rising edge, 1% hysteresis
CONDITIONS
kHz
255 300 345
Switching Frequency
540 600 660
850 1000 1150
µA1PWROK Output Current High
V0.4PWROK Output Voltage Low
%
6.5 8 9.5
PWROK Trip Level
-7.5 -6 -4.5
%
2
AC Load Regulation
(Note 2)
1
0.5
mA0.5 4.0Reference Short-Circuit Current
V2.7 3.0Reference Undervoltage Lockout
V4.5 5.5Input Voltage Range
%
±1.5
±1
Output Voltage (FB) Accuracy
mV10Reference Load Regulation
V3.465 3.5 3.535Reference Voltage
mA0.1V
DD
Supply Current
V4.0 4.2Input Undervoltage Lockout
UNITSMIN TYP MAXPARAMETER
CSH - CSL =
0mV to 80mV
%
0.2
DC Load Regulation
(Note 2)
0.1
0.05
T
A
= +25°C to +85°C
T
A
= 0°C to +85°C
LG = GND
LG = REF
LG = V
CC
LG = GND
LG = REF
LG = V
CC
2.5FB overdrive = 200mV
5FB overdrive = 0V
Operating
mode
V
CC
= V
DD
= 5.5V
mA
3.6 10
V
CC
Supply Current
V
REF
= 0V
Shutdown
mode
0.3DAC code = 11111
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= V
CC
= D4 = +5V, PGND = AGND = D0–D3 = 0V, FREQ = REF, T
A
= 0°C to +85°C, unless otherwise noted.)
MAX1638
_______________________________________________________________________________________ 3
DH = DL = 2.5V
V
DD
= 4.5V
BST - LX = 4.5V
GND (low)
100mV overdrive
FREQ = V
CC
With respect to V
REF
,
FB going low
Minimum
D0–D4 = 0V
D0–D4, V
CC
= 5.5V
REF (mid)
CSH = CSL = 1.3V, D0–D3 = 5V, D4 = 0V
D0–D4, V
CC
= 4.5V
CONDITIONS
-2.75 -2 -1.25
V
CC
(high)
ns030DH, DL Dead Time
A2DH, DL Source/Sink Current
Ω
0.7 2
Maximum
DH On-Resistance 0.7 2
%
-3 -1
µA100CC2 Source/Sink Current
4V
CC
V
2.4 3.0
mmho1
kΩ10CC1 Output Resistance
µA±0.1
3.3 3.7
0.2
%85 90Maximum Duty Cycle
LG, FREQ Input Voltage
µA50CSH, CSL Input Current
µA4LG, FREQ Input Current
µA2510D0–D4 Source Current
V2.0Logic Input Voltage High
V
CC
- 0.1
V
0.8Logic Input Voltage Low
UNITSMIN TYP MAXPARAMETER
FB Input Current
CC2 Clamp Voltage
CC2 Transconductance
PDRV Trip Level
PDRV, NDRV Response Time FB overdrive = 5% ns75
PDRV, NDRV On-Resistance V
DD
= 4.5V Ω25
PDRV, NDRV Source/Sink Current PDRV = NDRV = 2.5V A0.5
PDRV, NDRV Minimum On-Time ns100
FB = 3.5V 85 100 115
Soft-Start Time To full current limit 1 / f
OSC
1536
BST Leakage Current BST = 12V, LX = 7V, REF = GND µA50
V
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
ΩDL On-Resistance
NDRV Trip Level
With respect to V
REF
,
FB going high
1.25 2 2.75
%
13
T
A
= +25°C
T
A
= 0°C to +85°C
T
A
= +25°C
T
A
= 0°C to +85°C
Current-Limit Trip Voltage
FB = 0V (Foldback)
mV
15 38 70
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

MAX1638EAG

Mfr. #:
Buy MAX1638EAG
Manufacturer:
Maxim Integrated
Description:
Switching Controllers High-Speed Step-Down Controller with Synchronous Rectification for CPU Power
Lifecycle:
New from this manufacturer.
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