LTC3200EMS8 Linear Technology, LTC3200EMS8 Datasheet - Page 7

• Manufacturer Part Number: LTC3200EMS8
• Description: IC SW CAP/DBLR .1A 8MSOP
• Manufacturer: Linear Technology
• Type: Switched Capacitor (Charge Pump), Doublerr

Specifications of LTC3200EMS8

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Current - Output: 100mA
• Frequency - Switching: 2MHz
• Voltage - Input: 2.7 ~ 4.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Output: -
• Power - Output: -

OPERATIO
Maximum Available Output Current
For the adjustable LTC3200, the maximum available out-
put current and voltage can be calculated from the effec-
tive open-loop output resistance, R
voltage, 2V
From Figure 2 the available current is given by:
Typical R
in Figure 3.
V
The style and value of capacitors used with the LTC3200/
LTC3200-5 determine several important parameters such
as regulator control loop stability, output ripple, charge
pump strength and minimum start-up time.
To reduce noise and ripple, it is recommended that low
ESR (< 0.1 ) ceramic capacitors be used for both C
and C
IN
I
, V
OUT
OUT
OUT
OL
. These capacitors should be 0.47 F or greater.
Capacitor Selection
2
IN(MIN)
Figure 2. Equivalent Open-Loop Circuit
V
values as a function of temperature are shown
Figure 3. Typical R
11
10
IN
9
8
–50
R
I
C
V
–
OUT
OL
FLY
FB
U
V
.
= 0V
+
–
–25
= 100mA
OUT
= 1 F
AMBIENT TEMPERATURE ( C)
2V
R
OL
IN
0
V
IN
OL
= 2.7V
25
vs Temperature
V
I
IN
OUT
50
OL
32005 F02
= 3.3V
, and effective output
+
–
75
V
32005 • F03
OUT
100
IN
Tantalum and aluminum capacitors are not recommended
because of their high ESR.
The value of C
ripple for a given load current. Increasing the size of C
will reduce the output ripple at the expense of higher
minimum turn on time and higher start-up current. The
peak-to-peak output ripple is approximately given by the
expression:
Where f
quency (typically 2MHz) and C
storage capacitor.
Both the style and value of the output capacitor can signifi-
cantly affect the stability of the LTC3200/LTC3200-5. As
shown in the Block Diagrams, the LTC3200/LTC3200-5
use a linear control loop to adjust the strength of the charge
pump to match the current required at the output. The
error signal of this loop is stored directly on the output
charge storage capacitor. The charge storage capacitor
also serves to form the dominant pole for the control loop.
To prevent ringing or instability on the LTC3200-5 it is
important for the output capacitor to maintain at least 0.47 F
of capacitance over all conditions. On the adjustable
LTC3200 the output capacitor should be at least 0.47 F
5V/V
Likewise excessive ESR on the output capacitor will tend
to degrade the loop stability of the LTC3200/LTC3200-5.
The closed loop output resistance of the LTC3200-5 is
designed to be 0.5 . For a 100mA load current change,
the output voltage will change by about 50mV. If the output
capacitor has 0.3
frequency response will cease to roll off in a simple one
pole fashion and poor load transient response or instabil-
ity could result. Ceramic capacitors typically have excep-
tional ESR performance and combined with a tight board
layout should yield very good stability and load transient
performance.
As the value of C
ripple, the value of C
present at the input pin (V
V
RIPPLEP P
OUT
OSC
to account for the alternate gain factor.
is the LTC3200/LTC3200-5’s oscillator fre-
OUT
LTC3200/LTC3200-5
2
directly controls the amount of output
f
OUT
OSC
or more of ESR, the closed loop
I
OUT
IN
•
controls the amount of output
C
controls the amount of ripple
OUT
IN
). The input current to the
OUT
is the output charge
7
OUT