MAX9949(2009) データシートの表示（PDF） - Maxim Integrated
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MAX9949 Datasheet PDF : 23 Pages
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Dual Per-Pin Parametric Measurement Units
Table 6. Current Range Selection
(BIT 12) RS2
0
0
0
0
1
1
1
1
(BIT 11) RS1
0
0
1
1
0
0
1
1
(BIT 10) RS0
0
1
0
1
0
1
0
1
RANGE
±2µA
±2µA
±20µA
±200µA
±2mA
±25mA
External
±25mA
NOMINAL RESISTOR VALUE
R_E = 1MΩ
R_E = 1MΩ
R_D = 100kΩ
R_C = 10kΩ
R_B = 1kΩ
R_A = 80Ω
—
R_A = 80Ω
Table 7. Clamp Enable
CLENABLE
1
0
MODE
Clamps enabled
Clamps disabled
rent) or MI (measure current). Table 6 describes the
full-scale current-range control.
Clamp Enable
The CLENABLE bit enables the force-output voltage
clamps when high and disables the clamps when low.
Table 7 depicts the various clamp mode options.
Measure Output High-Impedance Control
The MSR_ output attains a low-leakage, high-imped-
ance state by using the HI-ZMSR control bit or the HI-Z_
input. The 2 bits are logically ORed together to control
the MSR_ output. The HI-Z_ input allows external multi-
plexing among several PMU MSR_ outputs without
using the serial interface. Table 8 explains the various
output modes for the MSR_ output.
Digital Output (DOUT)
The digital output follows the last output of the serial
shift register and clocks out on the falling edge of the
input clock. DOUT provides the first bit of the incoming
Table 8. MSR_ Output Truth Table
(BIT 7) HI-ZMSR
1
HI-Z_
1
MSR_ STATE
Measure output enabled
0
1
High-Z
1
0
High-Z
0
0
High-Z
serial data word 16.5 clock cycles later. This allows for
daisy-chaining an additional device using DOUT and
the same clock.
“Quick Load” Using Chip Select
If CS goes low and then returns high without any clock
activity, the data from the input registers latch into the
PMU registers. This extra function is not standard for
SPI/QSPI/MICROWIRE interfaces. The quick load mim-
ics the function of LOAD without forcing LOAD low.
Comparators
Two comparators configured as a window comparator
monitor the MSR_ output. THMAX_ and THMIN_ set the
high and low thresholds that determine the window.
Both outputs are open drain and share a single disable
control that places the outputs in a high-Z, low-leakage
state. Table 9 describes the comparator output states
of the MAX9949/MAX9950.
Table 9. Comparator Truth Table
(BIT 6) DISABLE
CONDITION
DUTH_
DUTL_
0
X
High-Z
High-Z
1
VMSR > VTHMAX and VTHMIN
0
1
1
VTHMAX > VMSR > VTHMIN
1
1
1
VTHMAX and VTHMIN > VMSR
1
0
1
VTHMIN > VMSR > VTHMAX*
0
0
*VTHMAX > VTHMIN constitutes normal operation. This condition, however, has VTHMIN > VTHMAX and does not cause any problems with
the operation of the comparators.
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