MAX1637 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – Miniature, Low-Voltage, Precision Step-Down Controller

19-1321; Rev 1; 2/98
EVAALVUAAILTAIOBNLEKIT
Miniature, Low-Voltage,
Precision Step-Down Controller
General Description
The MAX1637 synchronous, buck, switch-mode power-
supply controller generates the CPU supply voltage in
battery-powered systems. The MAX1637 is a stripped-
down version of the MAX1636 in a smaller 16-pin QSOP
package. The MAX1637 is intended to be powered sep-
arately from the battery by an external bias supply (typi-
cally the +5V system supply) in applications where the
battery exceeds 5.5V. The MAX1637 achieves excellent
DC and AC output voltage accuracy. This device can
operate from a low input voltage (3.15V) and delivers the
excellent load-transient response needed by upcoming
generations of dynamic-clock CPUs.
Using synchronous rectification, the MAX1637 achieves
up to 95% efficiency. Efficiency is greater than 80%
over a 1000:1 load-current range, which extends bat-
tery life in system-suspend or standby mode. Excellent
dynamic response corrects output load transients
caused by the latest dynamic-clock CPUs within five
300kHz clock cycles. Powerful 1A on-board gate driv-
ers ensure fast external N-channel MOSFET switching.
The MAX1637 features a logic-controlled and synchro-
nizable, fixed-frequency, pulse-width-modulation
(PWM) operating mode. This reduces noise and RF
interference in sensitive mobile-communications and
pen-entry applications. Asserting the SKIP pin enables
fixed-frequency mode, for lowest noise under all load
conditions. For a stand-alone device that includes a
+5V VL linear regulator and low-dropout capabilities,
refer to the MAX1636 data sheet.
________________________Applications
Notebook Computers
Subnotebook Computers
Handy-Terminals, PDAs
__________________Pin Configuration
____________________________Features
o ±2% DC Accuracy
o 0.1% (typ) DC Load Regulation
o Adjustable Switching Frequency to 350kHz
o Idle Mode™ Pulse-Skipping Operation
o 1.10V to 5.5V Adjustable Output Voltage
o 3.15V Minimum IC Supply Voltage (at V_CC pin)
o Internal Digital Soft-Start
o 1.1V ±2% Reference Output
o 1µA Total Shutdown Current
o Output Overvoltage Crowbar Protection
o Output Undervoltage Shutdown (foldback)
o Tiny 16-Pin QSOP Package
______________Ordering Information
PART
MAX1637EEE
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
16 QSOP
__________Typical Operating Circuit
V_BIAS V_BATT
V_CC
V_GG
SHDN
MAX1637
DH
BST
TOP VIEW
CSH 1
16 SKIP
CSL 2
FB 3
CC 4
MAX1637
15 LX
14 DH
13 BST
REF 5
12 PGND
SHDN 6
SYNC 7
GND 8
11 DL
10 V_GG
9 V_CC
QSOP
Idle Mode is a trademark of Maxim Integrated Products.
CC
REF
SKIP
SYNC
GND
LX
DL
PGND
CSH
CSL
FB
OUTPUT
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