TS4604 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
TS4604
STMicroelectronics
TS4604 Datasheet PDF : 31 Pages
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TS4604
Application information
6.7
Performance of CMRR
When the TS4604 is used in differential mode (Figure 46), because of the resistor matching
the CMRR can have important variations.
To minimize these variations, we recommend using the same kind of resistor (same
tolerance).
The following equation is valid for frequencies ranging from DC to about kHz. The equation
is simplified by neglecting the ΔR² terms. ΔR is the tolerance value as a percentage.
CMRR ≈
20 ⋅
log
-1----0---0---
4ΔR
⎝⎛1
+
R-R----fi--nd--⎠⎞
(dB)
It is extremely important to correctly match the resistors to obtain a good CMRR.
All the tests have been performed with resistors with a tolerance value of 0.1%.
Example:
With ΔR = 1% the minimum CMRR would be 34 dB.
With ΔR = 0.1% the minimum CMRR would be 54 dB.
6.8
6.8.1
6.8.2
Internal and external undervoltage detection
The TS4604 embeds two UVLOs: one internal and one external.
Internal UVLO
The internal UVLO monitors the power supply via pins PVCC_HP (20) and PVCC_LD(23).
The threshold is set to 2.8 V with a 200 mV hysteresis. If the power supply decreases to
2.6 V, the TS4604 switches to standby mode. To switch the device on again, the power
supply voltage must increase to above 2.8 V.
Refer to Table 4 for the tolerance of the UVLO voltage.
External UVLO
The Ex_UVP pin (25) is an external undervoltage detection input that can be used to start
up or shutdown the TS4604 by applying the correct voltage value. A 1.25 V internal
precision voltage is used as a reference to monitor the voltage applied to the Ex_UPVP pin.
To set a desired shutdown threshold and hysteresis for the application, a resistor divider can
be calculated as follows.
Vuvp = 1.25V ⋅
(---R-----1----+-----R-----2----)
R1
Vhyst≈ 5μA ⋅
R3 ⋅
⎛
⎝
R-----2--
R1
+
1⎠⎞
with the condition R3>>R1//R2.
Doc ID 17913 Rev 1
21/31
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