Rainbow Electronics MAX1637 - Manual

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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
____________________________Features
♦ ±2% DC Accuracy
♦ 0.1% (typ) DC Load Regulation
♦ Adjustable Switching Frequency to 350kHz
♦ Idle Mode™ Pulse-Skipping Operation
♦ 1.10V to 5.5V Adjustable Output Voltage
♦ 3.15V Minimum IC Supply Voltage (at V CC pin)
♦ Internal Digital Soft-Start
♦ 1.1V ±2% Reference Output
♦ 1µA Total Shutdown Current
♦ Output Overvoltage Crowbar Protection
♦ Output Undervoltage Shutdown (foldback)
♦ Tiny 16-Pin QSOP Package
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
________________________________________________________________ Maxim Integrated Products 1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
CSH SKIP
LX
DH
BST
PGND
DL
V GG
V
CC
TOP VIEW
MAX1637
QSOP
CSL
FB
SHDN
CC
REF
SYNC
GND
__________________Pin Configuration
__________Typical Operating Circuit
19-1321; Rev 1; 2/98
PART
MAX1637EEE -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
16 QSOP
EVALUATION KIT
AVAILABLE
______________Ordering Information
Idle Mode is a trademark of Maxim Integrated Products.
MAX1637
SHDN
GND
V BATT V BIAS
DL
PGND
LX
DH
V CC V GG
BST
CSH
CSL
FB
SKIP
SYNC
REF
CC
OUTPUT