ADP1053 AD [Analog Devices], ADP1053 Datasheet - Page 19

• Manufacturer Part Number: ADP1053
• Description: 3-Channel Digital
• Manufacturer: AD [Analog Devices]

Data Sheet
The accurate ADC reading is used for CS2 overcurrent
protection (OCP) and monitoring. For more information,
see the CS2_A and CS2_B Accurate OCP Flags section and
the CS2 (CS2_A/CS2_B) Readings section.
SR FETs REVERSE CURRENT PROTECTION
In synchronous rectification applications, reverse current may
flow from V
sense resistor to the power ground. If the SR FETs are kept on,
the large reverse current can damage the SR FETs or the gate
driver circuit under extreme conditions.
SR FET reverse current protection is implemented using analog
comparators. The reverse current protection threshold can be
set using Register 0xFE84 and Register 0xFE85. If the voltage
difference between CS2− and CS2+ is greater than the reverse
current protection threshold programmed in these registers, the
flag (REVERSE_A or REVERSE_B) is triggered. The action
taken when the threshold is triggered can be programmed in
Register 0xFE83.
CONTROL LOOPS AND FEEDBACK REFERENCES
Channel A and Channel B each have an independent voltage
feedback control loop. The feedback uses the sensed signals
from VS+_A and VS−_A (for Channel A) and VS+_B and
VS−_B (for Channel B).
Register 0xFE22 and Register 0xFE24 set the reference voltage
for Channel A; Register 0xFE23 and Register 0xFE25 set the
reference voltage for Channel B. Each LSB corresponds to the
LSB of the VS_A/VS_B accurate ADC, which is 390.6 μV (see
the VS_A and VS_B Readings section).
OUT
CS2–_A/
CS2–_B
Figure 17. SR FET Reverse Current Protection
200µA
through an output inductor, SR FETs, and a
R
SENSE
CS2+_A/
CS2+_B
200µA
PROTECTION THRESHOLD
REVERSE CURRENT
V
OUT
ADC
12 BITS
DEBOUNCE
ADP1053
FLAG
Rev. A | Page 19 of 84
The output voltage must be divided down using a resistor divider
network (R1 and R2 in Figure 11) to set up a feedback voltage at
the VS_A/VS_B pins. To convert the register value to an output
voltage reference, use the following equation:
For example, in a 12 V system with an 11 kΩ and 1 kΩ resistor
divider, the reference voltage register value for Channel A is 0xB00
(2816 decimal). This register value is converted as follows:
To prevent the writing of invalid voltage reference values to the
registers, the value written to the registers does not take effect in
the closed-loop operation until the GO command is executed.
For Channel A, the GO command is executed by writing 1 to
Bit 0 in Register 0xFE61. For Channel B, the GO command is
executed by writing 1 to Bit 1 in Register 0xFE61. This function
allows the user to read back and confirm the reference register
value before implementing it for closed-loop operation.
In addition, to prevent a channel from outputting a voltage that
is outside its capability, Register 0xFE1E through Register 0xFE21
can be used to set the high and low limits for the feedback refer-
ences. The reference registers can only be set to values between
the low and high limits. If the user attempts to write a value that
is out of range to the reference register, the value is ignored and
the voltage setting error flag (VS_SET_ERR_A or VS_SET_
ERR_B) is set.
Note that the VS_SET_ERR_x flag is set during the writing of
the invalid value and is cleared when the write fails; the latched
flag is also set but is not cleared.
If the reference register value is not modified but the reference
limit register is modified such that the reference is out of range,
the write is successful. However, the reference value remains
unchanged, and the VS_SET_ERR_x flag is set.
VOLTAGE SETTING WITH SLEW RATE
The
with slew rate control. The slew rate is set using Bits[3:1] of
Register 0xFE86 (for VS_A) and Register 0xFE87 (for VS_B).
The slew rate function is enabled by setting Bit 0 in Register
0xFE86 or Register 0xFE87. When a slew rate is enabled and the
ADP1053
ADP1053
ADP1053
V
V
OUT
OUT
= VS_Ref_Voltage_Value × 390.6 μV × (R1 + R2)/R2
= 2816 × 390.6 μV × (11 kΩ + 1 kΩ)/1 kΩ = 13.2 V
receives an output voltage adjustment command, the
adjusts the voltage setting with the preset slew rate.
provides a method for output voltage adjustment
ADP1053