LTC1700EMS Linear Technology, LTC1700EMS Datasheet - Page 6

• Manufacturer Part Number: LTC1700EMS
• Description: IC DC/DC CONTRLR STP-UP 10-MSOP
• Manufacturer: Linear Technology
• Type: Step-Up (Boost)r

Specifications of LTC1700EMS

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Current - Output: 1A
• Frequency - Switching: 530kHz
• Voltage - Input: 0.9 ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Output: -
• Power - Output: -

FUNCTIONAL DIAGRA
LTC1700
OPERATIO
RUN/SS
6
Main Control Loop
The LTC1700 is a constant frequency, current mode
controller for DC/DC step-up converters. In normal opera-
tion, the main external N-channel power MOSFET is turned
on when the oscillator sets a latch and turned off either
when the V
duty cycle has reached 90%. When the main MOSFET is
turned off, the synchronous rectifier P-channel MOSFET is
SYNC/
MODE
SGND
V
OUT
V
I
TH
FB
U
5
2
3
4
1
7
1.205V
DS
+
–
INHIBIT
BURST
g
U
sense amplifier (V
m
OSCILLATOR
REFERENCE
X
START-UP
EA
–
= 0.9m
1.205V
SC
U
Ω
Y
+
(Refer to Functional Diagram)
MAIN
OSC
Y = “0” ONLY WHEN X IS A CONSTANT “1”, OTHERWISE Y = “1”
= “1” WHEN V
S
R
SOFT-START
L1
RUN/
QB
Q
OUT
DS
) resets the latch or the
< 2.3V
W
I
CMP
V
OUT
0.12V
+
–
SHDN
SLOPE
COMP
3.8µA
60mV
–
+
–
+
SW
BURST
10
1Ω
V
M1
REF
+ 58mV
turned on until either the inductor current is about to
reverse, as determined by the current reversal comparator
(I
measured by sensing the V
ducting MOSFET. The peak inductor current is controlled
by the voltage on the I
error amplifier (EA). An external resistive divider con-
nected between V
V
9mV
RCMP
OUT
V
FB
), or the next cycle begins. Inductor current is
+
–
+
+
–
–
I
RCMP
V
CYCLE LIMIT
OV
90% DUTY
DS
SLEEP
OUT
and GND allows EA to receive an
TH
SWITCHING
BLANKING
CIRCUIT
LOGIC
pin, which is the output of the
AND
DS
potential across the con-
V
OUT
V
OUT
0.36V
1700 • FD
V
CC
6
8
9
1700fa
TG
BG
PGND