ltc3827ig-1 Linear Technology Corporation, ltc3827ig-1 Datasheet - Page 7

• Manufacturer Part Number: ltc3827ig-1
• Description: Low Iq, Dual, 2-phase Synchronous Step-down Controller
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
I
Switching Regulator Compensation Points. Each associa-
ted channel’s current comparator trip point increases
with this control voltage.
V
feedback voltage for each controller from an external
resistive divider across the output.
SENSE1
Differential Current Comparators. The I
controlled offsets between the SENSE
in conjunction with R
SENSE1
Differential Current Comparators.
PLLLPF (Pin 5): The phase-locked loop’s lowpass filter
is tied to this pin when synchronizing to an external
clock. Alternatively, tie this pin to GND, INTV
floating to select 250kHz, 530kHz or 400kHz switching
frequency.
PLLIN/MODE (Pin 6): External Synchronization Input to
Phase Detector and Forced Continuous Control Input. When
an external clock is applied to this pin, the phase-locked
loop will force the rising TG1 signal to be synchronized
with the rising edge of the external clock. In this case, an
R-C filter must be connected to the PLLLPF pin. When not
synchronizing to an external clock, this input, which acts
on both controllers, determines how the LTC3827-1 oper-
ates at light loads. Pulling this pin below 0.7V selects Burst
TYPICAL PERFOR A CE CHARACTERISTICS
TH1,
FB1
4.2
4.1
4.0
3.9
3.8
3.7
3.6
3.5
3.4
3.3
3.2
U
–45
, V
Undervoltage Lockout Threshold
vs Temperature
I
TH2
–30
FB2
+
–
, SENSE2
, SENSE2
U
–15
(Pins 1, 13): Error Amplifier Outputs and
(Pins 2, 12): Receives the remotely sensed
TEMPERATURE (°C)
0
RISING
FALLING
15
+
–
U
SENSE
(Pins 3, 11): The (+) Input to the
(Pins 4, 10): The (–) Input to the
30
45
set the current trip threshold.
W
60
38271 G25
75
U
90
–
TH
and SENSE
pin voltage and
404
402
400
398
396
392
394
5
Oscillator Frequency
vs Input Voltage
CC
or leave
10
+
pins
INPUT VOLTAGE (V)
15
20
Mode operation. Tying this pin to INTV
ous inductor current operation. Tying this pin to a voltage
greater than 0.9V and less than INTV
skipping operation.
SGND (Pin 7): Small Signal Ground common to both
controllers, must be routed separately from high current
grounds to the common (–) terminals of the C
RUN1, RUN2 (Pins 8, 9): Digital Run Control Inputs for
Each Controller. Forcing either of these pins below 0.7V
shuts down that controller. Forcing both of these pins
below 0.7V shuts down the entire LTC3827-1, reducing
quiescent current to approximately 8μA.
INTV
Regulator. The driver and control circuits are powered from
this voltage source. Must be decoupled to power ground with
a minimum of 4.7μF tantalum or other low ESR capacitor.
EXTV
Connected to INTV
bypassing the internal LDO powered from V
EXTV
Applications Information section. Do not exceed 10V on
this pin.
PGND (Pin 21): Driver Power Ground. Connects to the
sources of bottom (synchronous) N-channel MOSFETs, an-
odes of the Schottky rectifiers and the (–) terminal(s) of C
V
be tied between this pin and the signal ground pin.
IN
(Pin 22): Main Supply Pin. A bypass capacitor should
25
CC
CC
CC
(Pin 19): Output of the Internal Linear Low Dropout
(Pin 20): External Power Input to an Internal LDO
is higher than 4.7V. See EXTV
30
38271 G26
35
CC
. This LDO supplies INTV
12
10
8
6
4
0
2
–45
Shutdown Current
vs Temperature
–30
–15
TEMPERATURE (°C)
CC
0
LTC3827-1
CC
–0.5V selects pulse-
15
CC
Connection in the
30
forces continu-
IN
IN
45
capacitors.
CC
whenever
60
power,
75
38271 G27
38271fd
7
IN
90
.