Datasheet
6
LT1528
1528fa
Ripple Rejection Load Regulation
Transient Response Transient Response
OUTPUT (Pin 1): The OUTPUT pin supplies power to the
load. A minimum output capacitor of 3.3µF is required to
prevent oscillations. Larger values will be needed to
achieve the transient performance required by high speed
microprocessors. See the Applications Information sec-
tion for more on output capacitance and reverse output
characteristics.
SENSE (Pin 2): The SENSE pin is the input to the error
amplifier. Optimum regulation will be obtained at the point
where the SENSE pin is connected to the OUTPUT pin. For
most applications the SENSE pin is connected directly to
the OUTPUT pin at the regulator. In critical applications
small voltage drops caused by the resistance (R
P
) of PC
traces between the regulator and the load, which would
normally degrade regulation, may be eliminated by con-
necting the SENSE pin to the OUTPUT pin at the load as
shown in Figure 1 (Kelvin Sense Connection). Note that the
voltage drop across the external PC traces will add to the
dropout voltage of the regulator. The SENSE pin bias
current is 150µA at the nominal regulated output voltage.
See SENSE Pin Current vs Temperature in the Typical
Performance Characteristics section. This pin is internally
clamped to –0.6V (one V
BE
).
The SENSE pin can also be used with a resistor divider to
achieve output voltages above 3.3V. See the Applications
Information section for information on adjustable operation.
FREQUENCY (Hz)
20
RIPPLE REJECTION (dB)
30
50
70
80
10 1k 10k 1M
LT1528 • TPC19
10
100
100k
60
40
0
I
OUT
= 1.5A
V
IN
= 6V + 50mV
RMS
RIPPLE
C
OUT
= 4 × 47µF
SOLID TANTALUM
C
OUT
= 47µF
SOLID TANTALUM
TEMPERATURE (°C)
–50
LOAD REGULATION (mV)
0
–5
–10
–15
–20
–25
–30
25 75
LT1528 • TPC20
–25 0
50 100 125
V
IN
= V
OUT
(NOMINAL) + 1V
∆I
LOAD
= 1mA TO 3A
TIME (µs)
0
OUTPUT VOLTAGE
DEVIATION (mV)
LOAD CURRENT (A)
100
50
0
–50
–100
3
2
1
0
160
LT1528 • TPC22
4020 60 100 140 180
80
120
200
V
IN
= 5V
C
IN
= 3.3µF
C
OUT
= 4 × 47µF
TIME (µs)
0
OUTPUT VOLTAGE
DEVIATION (mV)
LOAD CURRENT (A)
100
50
0
–50
–100
3
2
1
0
160
LT1528 • TPC21
4020 60 100 140 180
80
120
200
V
IN
= 5V
C
IN
= 3.3µF
C
OUT
= 47µF
UU
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PI FU CTIO S
TYPICAL PERFOR A CE CHARACTERISTICS
UW