lt3070 Linear Technology Corporation, lt3070 Datasheet - Page 13

• Manufacturer Part Number: lt3070
• Description: 5a, Low Noise, Programmable Output, 85mv Dropout Linear Regulator
• Manufacturer: Linear Technology Corporation

pin Functions
MARGSEL (Pin 21): Margining Enable and Polarity Selec-
tion. This three-state pin determines both the polarity and
the active state of the margining function. The logic low
threshold is less than 250mV referenced to GND and en-
ables negative voltage margining. The logic high t hreshold
is greater than V
margining. The voltage range between these two logic
thresholds as set by a window comparator defines the
logic Hi-Z state and disables the margining function.
MARGTOL (Pin 22): Margining Tolerance. This three-
state pin selects the absolute value of margining (1%,
3% or 5%) if enabled by the MARGSEL input. The logic
low threshold is less than 250mV referenced to GND and
enables either ±1% change in V
of the MARGSEL pin. The logic high threshold is greater
than V
V
voltage range between these two logic thresholds as set
by a window comparator defines the logic Hi-Z state and
enables either ±3% change in V
of the MARGSEL pin.
OUT
depending on the state of the MARGSEL pin. The
+
BIAS
+
V
– 250mV and enables either ±5% change in
BIAS
V
IN
Figure 1. Kelvin Sense Connection
BIAS
– 250mV and enables positive voltage
IN
EN
V
V
V
MARGSEL
MARGTOL
VIOC
O2
O1
O0
LT3070
BIAS
GND
REF/BYP
OUT
OUT
PWRGD
SENSE
OUT
depending on the state
depending on the state
R
R
P
P
3070 F01
LOAD
V
lect. These three-state pins combine to select a nominal
output voltage from 0.8V to 1.8V in increments of 50mV.
Output voltage is limited to 1.8V maximum by an internal
override of V
threshold is less than 250mV referenced to GND and the
logic high threshold is greater than V
range between these two thresholds as set by a window
comparator defines the logic Hi-Z state. See Table 1 in the
Applications Information section that defines the V
and V
BIAS (Pin 27): Bias Supply. This pin supplies current to
the internal control circuitry and the output stage driving
the pass transistor. The LT3070 requires a minimum 2.2µF
bypass capacitor for stability and proper operation. To
ensure proper operation, the BIAS voltage must satisfy
the following conditions: 2.2V ≤ V
(1.25 • V
voltage is limited to 2.2V.
EN (Pin 28): Enable. This pin enables/disables the output
device only. The internal reference and all support functions
are active if V
EN low keeps the reference circuit active, but disables
the output pass transistor and puts the LT3070 into a low
power nap mode. Drive the EN pin with either a digital logic
port or an open-collector NPN or an open-drain NMOS
terminated with a pull-up resistor to V
resistor must be less than 35k to meet the V
of the EN pin. If unused, connect EN to BIAS.
O0
, V
O0
O1
settings versus V
OUT
and V
+ 1V). For V
O1
BIAS
O2
when V
is above its UVLO threshold. Pulling
(Pins 23, 24, 25): Output Voltage Se-
O2
OUT
OUT
= high. The input logic low
≤ 0.95V, the minimum BIAS
.
BIAS
≤ 3.6V and V
BIAS
BIAS
– 250mV. The
LT3070
. The pull-up
IH
condition

O2
BIAS
, V
3070f
O1
≥