I am evaluating an LT1997(-3) as a high-side current sense amp in a single-polarity system, up to 100+VDC.
I modeled it in LTSpice, and am seeing unexpected results.
The model doesn't seem to work with a single +5V supply, and gain configurations other than x1 don't seem to work correctly at all.
This should implement two amplifiers, the upper (U1) with gain x1, U2 with gain x10.
Vout and I(Rld) plot look fine, with a small offset in Vout, but gain as expected. (10A --> 100.85mV)
But Vout1 rises to only 668mV (at ~6.66A Rld1), then crashes to the -15V rail, long before the current reaches 10A.
What am I overlooking??
* LT1997-3 Hi-side sensor x2.asc XU1 N001 MP_01 NC_02 MP_03 NC_04 0 0 V- Vout NC_05 V+ NC_06 MP_07 NC_08 MP_09 N003 LT1997-3 Vbus N001 0 PULSE(0 100 0.1 0.5) V2 V+ 0 15 V3 V- 0 -15 Rsns N001 N002 10m Rld N002 0 10 R1 N003 N002 10m XU2 N004 MP_10 NC_11 MP_12 N004 0 0 V- Vout1 NC_13 V+ N006 MP_14 NC_15 MP_16 N006 LT1997-3 Vbus1 N004 0 PULSE(0 100 0.7 0.5) Rsns1 N004 N005 10m Rld1 N005 0 10 R2 N006 N005 10m .tran 1.4 .lib LTC6.lib .backanno .end