lt1940l Linear Technology Corporation, lt1940l Datasheet - Page 6
![no-image](/images/manufacturer_photos/0/3/389/linear_technology_corporation_sml.jpg)
lt1940l
Manufacturer Part Number
lt1940l
Description
Lt1940l - Dual Monolithic 1.4a, 1.1mhz Step-down Switching Regulator
Manufacturer
Linear Technology Corporation
Datasheet
1.LT1940L.pdf
(20 pages)
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
lt1940lEFE
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Company:
Part Number:
lt1940lEFE#PBF
Manufacturer:
LT
Quantity:
5 000
BLOCK DIAGRA
LT1940/LT1940L
The LT1940 is a dual, constant frequency, current mode
buck regulator with internal 2A power switches. The two
regulators share common circuitry including input source,
voltage reference and oscillator, but are otherwise inde-
pendent. This section describes the operation of the
LT1940; refer to the Block Diagram.
If the RUN/SS (run/soft-start) pins are both tied to ground,
the LT1940 is shut down and draws 30 A from the input
source tied to V
external soft-start capacitors, generating voltage ramps at
6
C
F
CLK
Figure 2. Block Diagram of the LT1940 with Associated External Components (One of Two Switching Regulators Shown)
RUN/SS2
RUN/SS1
R
C
C
GND
V
C
PG
C
RUN/SS
2 A
2 A
SLOPE
IN
+
–
. Internal 2 A current sources charge
SLAVE
OSC
0.5V
W
0.75V
AND REF
INT REG
C1
V
IN
–
+
CLAMP
I
LIMIT
R
S
MASTER
OSC
Q
CLK1
CLK2
ERROR
these pins. If either RUN/SS pin exceeds 0.6V, the internal
bias circuits turn on, including the internal regulator,
1.25V reference and 1.1MHz master oscillator. In this
state, the LT1940 draws 3.5mA from V
both RUN/SS pins are high. Neither switching regulator
will begin to operate until its RUN/SS pin reaches ~0.8V.
The master oscillator generates two clock signals of
opposite phase.
The two switchers are current mode step-down regula-
tors. This means that instead of directly modulating the
AMP
–
+
+
–
125mV
1.25V
1940 F02
BOOST
SW
V
FB
IN
R2
C
D1
IN
IN
C3
D2
L1
R1
IN
, whether one or
C1
OUT
1940fa