MAX1763 Maxim, MAX1763 Datasheet - Page 9

• Manufacturer Part Number: MAX1763
• Description: 1.5A / Low-Noise / 1MHz / Step-Up DC-DC Converter
• Manufacturer: Maxim

Figure 1. Functional Diagram
Table 1. Typical Available Output Current
noise spectrum. See Table 1 for typical available output
current.
In its normal mode of operation (CLK/SEL = low), the
MAX1763 offers fixed-frequency PWM operation
through most of its load range. At light loads (less than
25% of full load), the device automatically optimizes
efficiency by switching only as needed to supply the
load. Shutdown reduces quiescent current to just 1µA.
Figure 2 shows the standard application circuit for the
MAX1763. (An external Schottky diode is needed for
output voltages greater than 4V, or to assist low-voltage
startup.)
1 NiCd/NiMH
2 NiCd/NiMH
1 Li+
1 Li+
3 NiCd/NiMH
OF CELLS
NUMBER
CLK/SEL
OUT
GND
ISET
ONA
ONB
REF
AIN
FB
VOLTAGE
2.7 (min)
2.7 (min)
_______________________________________________________________________________________
INPUT
IC POWER
2.15V
(V)
1.2
2.4
2.4
3.6
1.25V
ON
REF
VOLTAGE
OUTPUT
REFERENCE
UNDERVOLTAGE LOCKOUT
(V)
3.3
3.3
5.0
3.3
5.0
5.0
1.5A, Low-Noise, 1MHz, Step-Up
RDY
MODE/
DUAL
FB
CURRENT
OUTPUT
(mA)
1500
1300
1100
1600
675
950
0.938V
EN
Additional features include synchronous rectification for
high efficiency and increased battery life, and a gain
block that can be used to build a linear regulator using
an external P-channel MOSFET pass device. This gain
OSCILLATOR
Figure 2. PFM/PWM Automode Connection
EN
1MHz
NOTE: HEAVY LINES INDICATE HIGH-CURRENT PATHS.
OSCILLATOR
GAIN
BLOCK
0.22µF
STARTUP
C3
Q
REF
ONB
ISET
CLK/SEL
ONA
DC-DC Converter
PGND
MAX1763
MAX1763
D
EN
OSC
MODE
FB
CONTROLLER
GND
POUT
OUT
ISET
AIN
AO
1.5µH
LX
FB
0.7V TO 5.5V
L1
V
IN
Q
Q
MBR0520L
D1
R5
4.7Ω
C2
1.0µF
N
P
N
C4
2 x 100µF
POUT
PGND
AO
LX
OUT
3.3V
C1
47µF
9