Datasheet

LTC4151
7
4151ff
For more information www.linear.com/LTC4151
block DiagraM
operaTion
The LTC4151 accurately monitors high side current and
voltages. This device accepts a wide range of input volt-
ages from
as low as 7V up to 80V and consumes less
than
1.7mA quiescent current in normal operation. A
shutdown mode is available with the LTC4151 to reduce
the quiescent current to less than 300µA by pulling the
SHDN pin below 1V.
In default continuous scan mode after power-up, the
onboard 12-bit analog-to-digital converter (ADC) continu
-
ously and sequentially measures the high side differential
voltage
between SENSE
+
(Kelvin sense of V
IN
) and SENSE
–
(full-scale 81.92mV) through an internal sense amplifier,
the input voltage V
IN
(full-scale 102.4V) through an internal
voltage divider, and the voltage applied to the ADIN pin
(full-scale 2.048V). The reference voltage of the ADC is
internally set to 2.048V. The digital data obtained by the
ADC is stored in the onboard registers.
In snapshot mode, the LTC4151 can perform on-demand
measurement of a selected voltage without the need of
continuous polling by a master controller. The snapshot
mode is enabled by programming the control register
through the I
2
C interface. A status bit in the data register
monitors the ADC’s conversion. When the conversion is
completed, the 12-bit digital code of the measured voltage
is held in the corresponding data registers.
The LTC4151 provides an I
2
C interface to read the ADC
data from the data registers and to program the control
register. Tw o three-state pins, ADR0 and ADR1, are
used to decode nine device addresses (see Table 1). The
LTC4151 features a single SDA pin to handle both input
data and output data, while the LTC4151-1/LTC4151-2
provide separate data in (SDAI) and data out (SDAO on
the LTC4151-1 and SDAO on the LTC4151-2) pins to
facilitate opto-isolation.
SHUTDOWN
CONTROL
4151 BD
6.3V
I
2
C/
REGISTERS
DECODER
SHDN
(LTC4151)
V
IN
5µA
2k
R
S
V
REF
= 2.048V
SDA/SDAI
(LTC4151/
LTC4151-1)
ADR1
SCL
SDAO/SDAO
(LTC4151-1/
LTC4151-2)
ADR0
GND ADIN
15k
735k
INTERNAL
POWER
SENSE
+
SENSE
–
–
+
6V
12-BIT ADC
MUX
25X
6V
pin FuncTions
SHDN (LTC4151 Only): Shutdown Input. Internally pulled
up to 6.3V. Pull this pin below 1V to force the LTC4151
into shutdown mode. Leave this pin open if unused.
V
IN
: Supply Voltage Input. Accepts 7V to 80V. The voltage
at this pin is monitored by the onboard ADC with a full-
scale input range of 102.4V. SENSE
+
must be connected
to V
IN
for proper ADC readout.