MAX8688
Digital Power-Supply Controller/Monitor
with PMBus Interface
8 _______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1, 3 DVDD
Digital Power-Supply Input (3.3V, typ). Connect AVDD to DVDD externally. Connect a 0.1µF capacitor from
DVDD to DGND.
2 DGND Digital Ground. Connect AGND to DGND externally close to the device.
4 CLKIO
Clock Input/Output. User-configurable clock input/output signal. The system controller can provide a clock
input to synchronize the time bases of multiple MAX8688 devices. Alternatively, a MAX8688 can provide a
1MHz output clock to other MAX8688s for synchronization. See the MFR_MODE (D1h) section.
5 RST Active-Low SMBus Interface and Device Reset Line. Active-low logic input. See the
RST
Operation section.
6 SDA SMBus Data Line
7 SCL SMBus Clock Line
8, 9 N.C. No Connection. Not internally connected.
10 ENOUT
On/Off Signal Open-Drain Output. Typically used to turn on/off a POL power supply under the PMBus
command or A3/ONOFF control. See the ENOUT Operation and MFR_MODE (D1h) sections.
11 FLT
Fault Output, Active-Low Open-Drain Output. Typically connected to system controller/master interrupt
input.
12 A3/ONOFF
Dual-Functioned Three-State MAX8688 Slave Address Identifier (MSB) and POL On/Off Control using the
MFR_MODE Command. See the MAX8688 Address Assignment and A3/ONOFF Operation sections.
13 A2/SDAE
Dual-Functioned Three-State MAX8688 Slave Address Identifier and EEPROM I
2
C Data Line. See the
MAX8688 Address Assignment and External EEPROM Interface sections.
14 A1/SCLE
Dual-Functioned Three-State MAX8688 Slave Address Identifier (LSB) and EEPROM I
2
C Clock Line. See
the MAX8688 Address Assignment and External EEPROM Interface sections.
15 DACOUT
Analog Voltage Output of Internal 12-Bit DAC. Connect DACOUT to REFIN or FB of the DC-DC module with
high impedance in shutdown.
16 AGND Analog Ground. Connect AGND to DGND externally close to the device.
17 AVDD
Analog Power-Supply Input (3.3V, typ). Connect AVDD to DVDD externally. Connect 0.1µF capacitor from
AVDD to AGND.
18 REFO Buffered Reference Output. Connect a 1µF capacitor from REFO to ground.
19 RS_C Filter Capacitor Connection for V
SENSE
Amplifier
20 RS-
Differential Remote-Sense Input Return of the DC-DC Output Voltage. Connect RS- to the return terminal at
the load.
21 RS+
Differential Remote-Sense Input of DC-DC Output Voltage. Connect RS+ to the load terminal where the
output must be regulated.
22 ISN-
Differential-Sense Input Return of DC-DC Output Current. Connect ISN- to the negative end of the current-
sense resistor (Figure 3). In case of DCR sensing, connect ISN- to the return terminal of filter capacitor C
S
(Figure 7).
23 ISN+
Differential-Sense Input of DC-DC Output Current. Connect ISN+ to the positive end of the current-sense
resistor. In case of DCR sensing, connect ISN+ to the junction of filter resistor and capacitor (R
S
and C
S
)
(Figure 7).
24 ISN_C Filter Capacitor Connection for I
SENSE
Amplifier
—EP
Exposed Pad. Connect EP to the AGND plane for the POL for best temperature measurement performance.
Do not use EP as the main ground connection.
