LT1776CS8 Linear Technology, LT1776CS8 Datasheet - Page 16

• Manufacturer Part Number: LT1776CS8
• Description: IC SW REG STEP-DOWN HI-EFF 8SOIC
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LT1776CS8

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.24 ~ 34 V
• Current - Output: 700mA
• Frequency - Switching: 200kHz
• Voltage - Input: 7.4 ~ 40 V
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

LT1776
TYPICAL APPLICATIONS
Burst Mode Operation Configuration
Figure 4b demonstrates that power supply efficiency de-
grades with lower output load current. This is not surpris-
ing, as the LT1776 itself represents a fixed power overhead.
A possible way to improve light load efficiency is in Burst
Mode operation.
Figure 7 shows the LT1776 configured for Burst Mode
operation. Output voltage regulation is now provided in a
16
10V TO
C1: PANASONIC HFQ 39 F AT 63V
C2: AVX D CASE 100 F 10V
C3: 2200pF, X7R
40V
V
IN
TPSD107M010R0080
+
C1
U
Figure 6. Minimum Inductor Size Application
C5
90
80
70
60
50
40
30
20
1
6
1
V
V
V
SHDN
SYNC
IN
IN
IN
= 10V
= 20V
= 30V
C4, C5: 100pF, X7R OR COG/NPO
D1: MOTOROLA 100V, 1A, SMD SCHOTTKY
L1: COILCRAFT DO1608C-683
LT1776
GND
V
IN
MBRS1100 (T3)
5
4
V
LOAD CURRENT (mA)
V
SW
CC
FB
V
10
V
C
IN
2
3
7
8
= 40V
(a)
(b)
“bang-bang” digital manner, via comparator U2, an
LTC1440. Resistor divider R3/R4 provides a scaled ver-
sion of the output voltage, which is compared against U2’s
internal reference. Intentional hysteresis is set by the R5/
R6 divider. As the output voltage falls below the regulation
range, the LT1776 is turned on. The output voltage rises,
and as it climbs above the regulation range, the LT1776 is
turned off. Efficiency is maximized, as the LT1776 is only
powered up while it is providing heavy output current.
R3
22k
5%
D1
C3
100
68 H
L1
C4
1776 F06b
+
1000
C2
FOR 3.3V V
I
L1: 47 H, DO1608C-473
R1: 24.3K, R2: 14.7k
OUT
R1
36.5k
1%
R2
12.1k
1%
1776 F06a
: 0mA TO 500mA
V
5V
0mA to 400mA
OUT
OUT
VERSION: