19-1268; Rev 3; 8/05
KIT
ATION
EVALU
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B
AVAILA
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
Features
The MAX1636 is a synchronous, buck, switch-mode,
power-supply controller that generates the CPU supply
voltage in battery-powered systems. It achieves ±1%
output voltage accuracy and offers the excellent loadtransient response needed by upcoming generations of
dynamic-clock CPUs.
Up to 95% efficiency is achieved through synchronous
rectification and Maxim’s proprietary Idle Mode™ control scheme. Efficiency is greater than 80% over a
1000:1 load-current range, extending battery life in system-suspend or standby modes. Excellent dynamic
response corrects output load transients caused by the
latest dynamic-clock CPUs within five 300kHz clock
cycles. Strong, 1A, on-board gate drivers ensure fast,
external N-channel MOSFET switching.
♦ ±1% DC Accuracy (Adjustable Mode)
The MAX1636 features a logic-controlled and synchronizable, fixed-frequency, pulse-width-modulation (PWM)
operating mode that reduces noise and RF interference
in sensitive mobile communications and pen-entry applications. Holding SKIP high forces fixed-frequency mode
for lowest noise under all load conditions.
♦ Open-Drain Power-Good Output (RESET)
For a low-cost version that omits the +5V VL linearregulator block and comes in a smaller 16-pin QSOP
package, refer to the MAX1637 data sheet.
Applications
♦ Output Overvoltage Crowbar Protection
♦ Output Undervoltage Shutdown
♦ Adjustable Switching Frequency to 340kHz
♦ Low-Dropout Operation
♦ Idle Mode Pulse-Skipping Operation
♦ 1.10V to 5.5V Adjustable Output Voltage
♦ 2.5V/3.3V Dual-Mode Fixed-Output Settings
♦ Internal Digital Soft-Start
♦ 1.1V ±1% Reference Output
♦ 3μA (typ) Shutdown Current
♦ 20-Pin SSOP Package
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX1636EAP
-40°C to +85°C
20 SSOP
MAX1636EAP+
-40°C to +85°C
20 SSOP
+Denotes lead-free package.
Typical Operating Circuit
Notebook Computers
Subnotebook Computers
VIN
Desktop Computers
Bus-Termination Supplies
V+
OVP
VL
VCC
SHDN
Pin Configuration
TOP VIEW
CSH 1
20 SKIP
CSL 2
DH
BST
19 LX
RESET 3
CC
18 DH
SHDN 4
OVP 5
LX
17 BST
MAX1636
CC 6
MAX1636
16 PGND
15 DL
REF 7
14 VL
SYNC 8
13 V+
GND 9
11 FB
PGND
SYNC
12 VCC
GND 10
SKIP
DL
SSOP
CSH
GND
REF
GND
CSL
FB
RESET
TO μP
Idle Mode is a trademark of Maxim Integrated Products.
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX1636
General Description
