MAX1636 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – Low-Voltage, Precision Step-Down Controller for Portable CPU Power

19-1268; Rev 0; 8/97
EVAALVUAAILTAIOBNLEKIT
Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
_______________General Description
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 load-
transient response needed by upcoming generations of
dynamic-clock CPUs.
Up to 95% efficiency is achieved through synchronous
rectification and Maxim’s proprietary Idle Mode™ con-
trol scheme. Efficiency is greater than 80% over a
1000:1 load-current range, extending battery life in sys-
tem-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.
The MAX1636 features a logic-controlled and synchro-
nizable, fixed-frequency, pulse-width-modulation (PWM)
operating mode that reduces noise and RF interference
in sensitive mobile communications and pen-entry appli-
cations. Holding SKIP high forces fixed-frequency mode
for lowest noise under all load conditions.
For a low-cost version that omits the +5V VL linear-
regulator block and comes in a smaller 16-pin QSOP
package, refer to the MAX1637 data sheet.
________________________Applications
Notebook Computers
Subnotebook Computers
Desktop Computers
Bus-Termination Supplies
__________________Pin Configuration
____________________________Features
o ±1% DC Accuracy (Adjustable Mode)
o Output Overvoltage Crowbar Protection
o Output Undervoltage Shutdown
o Adjustable Switching Frequency to 340kHz
o Low-Dropout Operation
o Idle Mode Pulse-Skipping Operation
o 1.10V to 5.5V Adjustable Output Voltage
o 2.5V/3.3V Dual-Mode Fixed-Output Settings
o Internal Digital Soft-Start
o 1.1V ±1% Reference Output
o 3µA (typ) Shutdown Current
o Open-Drain Power-Good Output (RESET)
o 20-Pin SSOP Package
______________Ordering Information
PART
MAX1636EAP
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
20 SSOP
__________Typical Operating Circuit
V_IN
V+ SHDN OVP
VL
V_CC
TOP VIEW
CSH 1
CSL 2
RESET 3
SHDN 4
OVP 5
CC 6
REF 7
SYNC 8
GND 9
GND 10
MAX1636
20 SKIP
19 LX
18 DH
17 BST
16 PGND
15 DL
14 VL
13 V+
12 V_CC
11 FB
SSOP
Idle Mode is a trademark of Maxim Integrated Products.
CC
DH
BST
LX
MAX1636
DL
SKIP
SYNC
GND
PGND
CSH
CSL
REF
FB
RESET
GND
TO µP
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