LTC1516IS8 Linear Technology, LTC1516IS8 Datasheet - Page 4

• Manufacturer Part Number: LTC1516IS8
• Description: IC SW CAP/DBLR 5V 50MA 8SOIC
• Manufacturer: Linear Technology
• Type: Switched Capacitor (Charge Pump), Doublerr

Specifications of LTC1516IS8

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 5V
• Current - Output: 50mA
• Frequency - Switching: 600kHz
• Voltage - Input: 2 ~ 5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

LTC1516
APPLICATIONS
Operation
The LTC1516 uses a switched capacitor charge pump to
boost V
voltage. Regulation is achieved by sensing the output
voltage through an internal resistor divider and enabling
the charge pump when the output voltage droops below
the lower trip point of COMP2. When the charge pump is
enabled, a 2-phase, nonoverlapping clock controls the
charge pump switches. Clock 1 closes the S1 switches
which enable the flying capacitors, C1 and C2, to charge
up to the V
stack C1 and C2 in series with V
plate of C2 to the output capacitor at V
of charging and discharging continues at a free-running
frequency of 600kHz (typ) until the output has risen to the
upper trip point of COMP2 and the charge pump is
disabled. When the charge pump is disabled, the LTC1516
draws only 8 A (typ) from V
efficiency at low load conditions.
To achieve the highest efficiency over the entire V
the LTC1516 operates as either a doubler or a tripler
4
BLOCK
IN
IN
from 2V to 5V to a regulated 5V 4% output
voltage. Clock 2 closes the S2 switches which
DIAGRAM
0.22 F
0.22 F
10 F
V
IN
+
U
C2
C2
C1
C1
+
–
+
–
CHARGE PUMP SHOWN IN TRIPLER MODE, DISCHARGE CYCLE
INFORMATION
U
W
IN
IN
CHARGE PUMP
which provides high
S1A
S1B
S1C
S1D
W
and connect the top
OUT
S2A
S2B
S2C
. This sequence
U
IN
range,
CLOCK 1
CLOCK 2
CONTROL
LOGIC
depending on V
COMP2 determine whether the charge pump is in doubler
mode or tripler mode. COMP1 forces the part into tripler
mode if V
is > 2.55V, the part will be in doubler mode using only C2
as a flying capacitor. In doubler mode, if the output droops
by 50mV under heavy loads, COMP3 will force the charge
pump into tripler mode until V
trip point of COMP3. Under these V
the nominal V
the no load nominal V
output load results in efficiency greater than 80% with V
between 2.5V and 3V.
In shutdown mode, all circuitry is turned off and the part
draws only leakage current (< 1 A) from the V
V
CMOS input with a threshold of approximately V
however, the SHDN pin can be driven by logic levels that
exceed the V
when a logic high is applied to the SHDN pin. The SHDN pin
cannot float; it must be driven with a logic high or low.
OUT
is also disconnected from V
V
IN
COMP1
COMP2
COMP3
REF
is < 2.55V, regardless of output load. When V
IN
OUT
IN
voltage. The part enters shutdown mode
and output load conditions. COMP1 and
will be approximately 50mV lower than
OUT
S3
. This method of sensing V
V
OS
LTC1516 • BD
OUT
climbs above the upper
IN
IN
+
. The SHDN pin is a
and load conditions,
SHDN
V
OUT
10 F
IN
supply.
IN
IN
and
/2;
IN
IN