lm2711 National Semiconductor Corporation, lm2711 Datasheet - Page 3

• Manufacturer Part Number: lm2711
• Description: Step-up Pwm Dc/dc Converter Integrated With 4 Buffers
• Manufacturer: National Semiconductor Corporation

Pin Functions
V
switch. Minimize the metal trace area connected to this pin to
minimize EMI.
V
as close to the device as possible. The capacitor should
connect between V
SHDN(Pin 3): Shutdown Pin. The shutdown pin signal is
active low. A voltage of less than 0.3V disables the device. A
voltage greater than 0.85V enables the device.
FSLCT(Pin 4): Frequency Select Pin. Connecting FSLCT to
AGND selects a 600 kHz operating frequency for the switch-
ing regulator. Connecting FSLCT to V
operating frequency. If FSLCT is left floating, the switching
frequency defaults to 600 kHz.
Vs+(Pin 5): Supply pin for the four Gamma buffers. Bypass
this pin with a capacitor as close to the device as possible.
The capacitor should connect between Vs+ and GND.
GMA1-in(Pin 6):Gamma Buffer input pin.
GMA2-in(Pin 7): Gamma Buffer input pin.
GMA3-in(Pin 8): Gamma Buffer input pin.
GMA4-in(Pin 9): Gamma Buffer input pin.
NC(Pin 10):No Connection.
NC(Pin 11): No Connection.
Ordering Information
SW
IN
(Pin 2): Input Supply Pin. Bypass this pin with a capacitor
(Pin 1): This is the drain of the internal NMOS power
LM2711MTX-ADJ
LM2711MT-ADJ
Order Number
IN
and GND.
Package Type
IN
TSSOP-20
TSSOP-20
selects a 1.25 MHz
3
NSC Package Drawing
GMA4-out(Pin 12): Gamma Buffer output pin.
GMA3-out(Pin13): Gamma Buffer output pin.
GMA2-out(Pin 14): Gamma Buffer output pin.
GMA1-out(Pin 15): Gamma Buffer output pin.
SS(Pin 16): Softstart pin. Connect capacitor to SS pin and
AGND to slowly ramp inductor current on startup.
V
regulator. Connect resistor/capacitor network between V
pin and AGND for boost switching regulator AC compensa-
tion.
FB(Pin 18): Feedback pin. Set the output voltage by select-
ing values of R1 and R2 using:
Connect the ground of the feedback network to the AGND
plane, which can be tied directly to the GND pin.
AGND(Pin 19): Analog ground pin. Ground connection for
the Gamma buffers and the boost switching regulator. AGND
must be tied directly to GND at the pins.
GND(Pin 20): Power ground pin. Ground connection for the
NMOS power device of the boost switching regulator. GND
must be tied directly to AGND at the pins.
C
(Pin 17): Compensation Network for Boost switching
MTC20
MTC20
73 Units, Rail
2500 Units, Tape and Reel
Supplied As
www.national.com
C