ADP3204 Analog Devices, ADP3204 Datasheet - Page 7

• Manufacturer Part Number: ADP3204
• Description: 3-Phase IMVP-II and IMVP-III Core Controller for Mobile CPUs
• Manufacturer: Analog Devices

Pin
11
12
13
14
15
16
17
18–20
21
22
23
REV. 0
Mnemonic
CLAMP
DRVLSD
SS
COREFB
DACRAMP
DACOUT
GND
OUT1–3
CS1
CS2
CS3
Function
Clamp (Active High). This is open-drain output pin, via the assistance of an external pull-up
resistor, indicates that the core voltage should be clamped for its protection. To allow the highest
level of protection, the CLAMP signal is developed using both a redundant reference and a redun-
dant feedback path with respect to those of the main regulation loop. In a preferred and more
conservative configuration, the core voltage is clamped by an external FET. The initial protection
function is served when it is activated by detection of either an overvoltage or a reverse-voltage
condition on the COREFB pin. Due to loss of the latched signal at IC power-off, a backup protec-
tion function is served by connecting the pull-up resistor to a system “ALWAYS” regulator output
(e.g., V5_ALWAYS). If the external FET is used, this implementation will keep the core voltage
clamped until the ADP3204 has power reapplied, thus keeping protection for the CPU even after a
hard-failure power-down and restart (e.g., a shorted top or bottom FET).
Drive-Low Shutdown (Active Low). In its active state, this digital output pin indicates that the
lower FET of the core VR should be disabled. In the suggested application schematic, this pin is
directly connected to the pin of the same name on the ADP3415 or other driver IC. Drive-low
shutdown is normally activated by the DPRSLP signal corresponding to a light load condition, but a
number of dynamic conditions can override the control of this pin as needed.
Soft Start. The output of this analog I/O pin is a controlled current source used to charge or
discharge an external grounded capacitor; the input is the detected voltage that is indicative of
elapsed time. The pin controls the soft start time of the IC as well as the hiccup cycle time during
overload, including but not limited to short circuit. Hiccup operation was added to reduce short
circuit power dissipation by more than an order of magnitude, while still allowing an automatic
restart when the failure mode ceased. The hiccup operation can be overwritten and changed to
latched-off operation by clamping the SS pin voltage to a voltage level somewhere above ~ 0.2 V.
In this configuration, the controller does not restart after a hiccup cycle is initiated, but stays latched off.
Core Feedback. This high impedance analog input pin is used to monitor the output voltage for
setting the proper state of the PWRGD and CLAMP pins. It is generally recommended to RC-filter
the noise from the monitored core voltage, as suggested by the application schematic.
DAC Output Ramp Rate Setting. The rate at which the DAC output voltage can ramp up or down
from one voltage to another when the VID code changes can be controlled by an external
DACRAMP capacitor connected from this pin to the DACOUT pin. The time constant of the
DACOUT voltage variation is determined by the internal resistance appearing across the
DACRAMP and DACOUT pins, and the capacitance of the DACRAMP capacitor. Not having any
DACRAMP capacitor connected to these pins results in the fastest rate. Use of the DACRAMP rate
control and the Deeper Sleep Shift adjustment features are exclusive.
Digital-to-Analog Converter Output of the VID input. This output voltage is the VID controlled
reference voltage whose primary function is to determine the output voltage regulation point.
Ground
Outputs to Driver 1–3. These digital output pins are used to command the state of theswitched
nodes via the drivers. They should be connected to the IN pin of the drivers of the appropriate channels.
Current Sense, Channel 1. This high impedance analog input pin is used for providing negative
feedback of the current information for the first channel.
Current Sense, Channel 2. This high impedance analog input pin is used to provide negative
feedback of the current information for the second channel. The pin is also used to determine
whether the chip is acting as a single or a multiphase controller. If the CS2 pin is tied to VCC but
not to a sense resistor, then three-phase operation is disabled. In this condition, the second phase
output signal (OUT2) is not switching but stays static low; the first and third phase output signals
(OUT1 and OUT2) are switching in phase. It’s the user’s discretion to use only one or both of the
two signals to drive a single- or dual-channel power stage.
Current Sense, Channel 3. This high impedance analog input pin is used to provide negative
feedback of the current information for the third channel. The pin is also used to determine
whether the chip is acting as a dual- or three-phase controller. If the pin is tied to VCC but not to a
sense resistor, then three-phase operation is disabled; the chip works as a dual-phase controller. In
this condition, the third phase output signal (OUT3) is not switching but stays static low; the first
and second phase output signals (OUT1, OUT2) are interleaved out-of-phase signals. In single-
phase operation, CS3 should be left open instead of being tied to VCC.
PIN FUNCTION DESCRIPTIONS (continued)
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ADP3204