Datasheet

ADP1053 Data Sheet
Rev. A | Page 18 of 84
10241-012
DRIVER
ADC
CS1_A/
CS1_B
ADP1053
CS1 SENSING
REGISTERS
THRESHOLD
1.2V
CS1 OCP
V
OUT
Figure 13. Current Sense 1 (CS1) Operation
ADC
CS
ADP1053
CS SENSING
REGISTERS
THRESHOLD
CS OCP
V
IN
10241-013
Figure 14. Current Sense (CS) Operation
The CS ADCs measure the average current information, which
can be read via the PMBus/I
2
C interface. This information can
also be used for volt-second balance or current balance control.
For more information, see the Volt-Second Balance and Current
Balance section.
CS2 (CS2+_A/CS2+_B, CS2−_A/CS2−_B) Sensing
CS2_A and CS2_B are typically used for the monitoring and
protection of Channel A and Channel B, respectively. CS2_A/
CS2_B provide accurate current sensing and monitoring of
OCP conditions.
CS2_A/CS2_B current sensing can be configured using a low-
side sense resistor or a high-side sense resistor. Depending on
the common-mode voltage of the current sensing resistor, the
part must be programmed for low-side or high-side mode using
Bit 7 of Register 0xFE1A and Register 0xFE1B.
Typical configurations are shown in Figure 15 and Figure 16.
The differential inputs are fed into an ADC through a pair of
external resistors. Internal matching current sources (nominal
value of 200 µA for low-side sensing and 2 mA for high-side
sensing) are used to regulate the common-mode voltage of the
CS2 pins at approximately 1 V.
For both high-side and low-side current sensing, it is recom-
mended that a 500 pF to 1000 pF capacitor be connected from
the CS2_A/CS2_B pins to AGND.
When using low-side resistor current sensing, as shown in
Figure 15, the common-mode voltage at the sensing resistor is
approximately 0 V. The current sources are 200 µA in low-side
current sensing mode. Two matching 5 kΩ resistors are
recommended.
ADC
ADP1053
CS2 SENSING
REGISTERS
V
OUT
CS2–_A/
CS2–_B
CS2+_A/
CS2+_B
CS2_A/
CS2_B
OCP
5kΩ5kΩ
200µA 200µA
10241-014
THRESHOLD
R
SENSE
Figure 15. CS2 Low-Side Resistive Current Sensing
When high-side resistor current sensing is required, as shown
in Figure 16, the resistor value is calculated based on a 2 mA
high-side current source, as follows:
R = (V
OUT
− 1 V)/2 mA
For example, in a 28 V system with high-side current sensing,
the value of the resistors used at the CS2 pins is calculated by
R = (28 V − 1 V)/2 mA = 13.5 k
ADC
ADP1053
CS2 SENSING
REGISTERS
V
OUT
CS2+_A/
CS2+_B
CS2–_A/
CS2–_B
2mA 2mA
THRESHOLD
10241-015
CS2_A/
CS2_B
OCP
R
SENSE
Figure 16. CS2 High-Side Resistive Current Sensing
Matching resistors with 0.1% or better accuracy are recom-
mended to achieve the accuracy specifications.
The full-scale range of the CS2_A/CS2_B ADC is 120 mV. The
ADC registers have an update rate of 100 Hz with 12-bit resolution.