Datasheet

ADAS1000/ADAS1000-1/ADAS1000-2 Data Sheet
Rev. A | Page 28 of 80
ECG INPUTS—ELECTRODES/LEADS
The ADAS1000/ADAS1000-1/ADAS1000-2 ECG product
consists of 5 ECG inputs and a reference drive, RLD (right leg
drive). In a typical 5-lead/vector application, four of the ECG
inputs (ECG3_RA, ECG1_LA, ECG2_LL, ECG4_V1) would
be used in addition to the RLD path. This leaves one spare
ECG path (which could be used for other purposes, such as
calibration or temperature measurement). Both V1 and V2
input channels can be used for alternative measurements if
desired. When used in this way, the negative terminal of the
input stage can be switched to the fixed internal VCM_REF =
1.3 V; see details in Table 48.
In a 5-lead system, the ADAS1000/ADAS1000-1/ADAS1000-2
can provide Lead I, Lead II, and Lead III data or electrode data
directly via the serial interface at all frame rates. The other ECG
leads can be calculated by the user’s software from either the
lead data or the electrode data provided by the ADAS1000/
ADAS1000-1/ADAS1000-2. Note that in 128 kHz data rate, lead
data is only available when configured in analog lead mode as
shown in Figure 57. Digital lead mode is not available for this
data rate.
A 12-lead (10-electrode) system can be achieved using one
ADAS1000 or ADAS1000-1 device ganged together with one
ADAS1000-2 slave device as described in the Gang Mode
Operation section. Here, 9 ECG electrodes and one RLD
electrode achieve the 10 electrode system, again leaving one
spare ECG channel that could be used for alternate purposes as
suggested previously. In such a system, having nine dedicated
electrodes benefits the user by delivering lead information
based on electrode measurements and calculations rather
than deriving leads from other lead measurements.
Table 10 outlines the calculation of the leads (vector) from the
individual electrode measurements.
Table 10. Lead Composition
1
Lead Name Composition Equivalent
ADAS1000 or ADAS1000-1 I LA – RA
II LL – RA
III LL – LA
aVR
2
RA – 0.5 × (LA + LL) −0.5 × (I + II)
aVL
2
LA – 0.5 × (LL + RA) 0.5 × (I − III)
aVF
2
LL – 0.5 × (LA + RA) 0.5 × (II + III)
V1’ V1 – 0.333 × (LA + RA + LL)
V2’ V2 – 0.333 × (LA + RA + LL)
12 Leads Achieved by Adding ADAS1000-2 Slave V3’ V3 – 0.333 × (LA + RA + LL)
V4’ V4 – 0.333 × (LA + RA + LL)
V5’ V5 – 0.333 × (LA + RA + LL)
V6’ V6 – 0.333 × (LA + RA + LL)
1
These lead compositions apply when the master ADAS1000 device is configured into lead mode (analog lead mode or digital lead mode) with VCM = WCT = (RA + LA
+ LL)/3. When configured for 12-lead operation with a master and slave device, the VCM signal derived on the master device (CM_OUT) is applied to the CM_IN of the
slave device. For correct operation of the slave device, the device must be configured in electrode mode (see the FRMCTL register in Table 35).
2
These augmented leads are not calculated within the ADAS1000, but can be derived in the host DSP/microcontroller/FPGA.