CM3718 Datasheet, PDF (4/10 Pages) List of Unclassifed Manufacturers – 1.5A LOW NOISE PWM STEP DOWN REGULATOR

CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
FUNCTIONAL DESCRIPTION
The CM3718 step-down, pulse-width-modulated (PWM),
INPUTS
DC-DC converter has an adjustable output range from VREF The input voltage reference pin, VREF determine the output
to the input voltage (VIN). An internal synchronous rectifier
voltages (LX). If a specific voltage is forced at the VREF pin, the
improves efficiency and eliminates an external Schottky diode. output voltage follows the voltage at the VREF pin.
Fixed-frequency operation enables easy post-filtering, thereby
providing excellent noise characteristics. As a result, the
OTHER SUPPLY VOLTAGES
CM3718 is an ideal choice for many small wireless systems. Several inputs are provided for the supply voltages: PVIN and
VIN.
VREF
The PVIN provide the power supply to the power MOSFETs.
The reference voltage could be ranged from 1.1V to VIN.
VIN provides the voltage supply to the logic section and internal
error amplifiers.
OUPUTS
The output voltage pins (LX) are tied to the RF power amp, FEEDBACK
via an external inductor. Output voltage is determined by the The VFB pin is an input that can be used for closed loop
VREF inputs.
compensation. This input is derived from the voltage output.
AGND pin is a contact node of internal resistor divider for
remote sense.
APPLICATION CIRCUIT
2
1
J1
PWR/IN
TP1
4
BNC
1
3
2
1
J2
VTT
1
2
J3
VREF-OUT
C7
104
R5
0
VDD
D1
SK12
L1
3.3uH/2A
D2
SK12
C6
47uf/6.3V
C1 100uf/6.3V
JP1
JUMPER
C2 105
1
2
R1
100k
1
R2
1k
2
C3
470
U3
CM3718-8PIN
VCC
1
105 C4
R8
5.1
2
JUMPER
VDD JP2
C5 104P
JP4 on/off sw
JP3
1
2
3
CON3
2
1
R3
100k
NOTE:
JP3---->USEING EXTERNAL
VOLTAGE SETING BOARD
(PIN 1,2 SHORT)
VCC
1
R4
470
2
1
R7
0
2
U2 CM-431
1
3
2005/02/02 Rev. 1.5
Champion Microelectronic Corporation
Page 4