LT1431CS8 Linear Technology, LT1431CS8 Datasheet - Page 7

• Manufacturer Part Number: LT1431CS8
• Description: IC REF PROGRAMMABLE .4%TOL 8SOIC
• Manufacturer: Linear Technology

Specifications of LT1431CS8

• Reference Type: Shunt, Adjustable
• Voltage - Output: 2.5 ~ 36 V
• Tolerance: ±0.4%
• Temperature Coefficient: 30ppm/°C
• Number Of Channels: 1
• Current - Cathode: 600µA
• Current - Output: 100mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Input: -
• Current - Quiescent: -

applicaTions inForMaTion
Frequency Compensation
As a shunt regulator, the LT1431 is stable for all capacitive
loads on the COLL pin. Capacitive loading between 0.01µF
and 18µF causes reduced phase margin with some ringing
under transient conditions. Output capacitors should not
be used arbitrarily because output noise is not necessarily
reduced.
Excess capacitance on the REF pin can introduce enough
phase shift to induce oscillation when configured as a
reference >2.5V. This can be compensated with capacitance
between COLL and REF (phase lead). More complicated
feedback loops may require shaping of the frequency
Typical applicaTions
V
IN
LT1431Z
2.5V Reference
3-Pin Package
R
∆ = R • (0.5mA) ±25% PROCESS TOLERANCE
∆ ≤ 500mV
R
L
CATHODE
V
R
ANODE
Increasing 5V Reference
GND-S
IN
TOP
V
+
REF
LT1431
R
LT1431 TA02
L
GND-F
COLL
R
2.5V
REF
MID
LT1431 TA05
5V + ∆
V
IN
GND-S
V
+
2.5V Reference
LT1431
8-Pin Package
R
L
GND-F
COLL
REF
response of the LT1431 with dominant pole or pole-zero
compensation. This can be accomplished with a capacitor or
series resistor and capacitor between COLL and COMP .
The compensation schemes mentioned above use voltage
feedback to stabilize the circuits. There must be voltage gain
at the COLL pin for them to be effective, so the COLL pin
must see a reasonable AC impedance. Capacitive loading
of the COLL pin reduces the AC impedance, voltage gain,
and frequency response, thereby decreasing the effective-
ness of the compensation schemes, but also decreasing
their necessity.
LT1431 TA03
2.5V
V
GND-S
IN
Programmable Reference with Adjustable
V
+
LT1431
R
LIM
R
L
GND-F
COLL
Current Limit
REF
V
R
IN
GND-S
TOP
I
LIMIT
V
+
5V Reference
LT1431
R1
R2
=
R
R
LIM
L
0.7
V
+ 3.6
GND-F
OUT
COLL
R
=
REF
AT 25°C
MID
( )
1 + R1
LT1431 TA06
LT1431 TA04
R2
LT1431
V
REF
5V
1431fd