
Pin Description
Pin
Pin Name
Pin Function
1
Vcc5V
Supply Voltage Input (5V nominal)
2
Divsel
Selects Phase Mode. Logic low selects 4 phase. Logic high selects 3 phase. 2 phase
operation is achieved by using 2 outputs in 4 phase mode.
3
Clksel
Clock Select: Logic high selects internal clock. Logic low selects external clock.
4
Extclk
External Clock Input. Output frequency = Clock Input / No. of Phases. Connect to Vcc5V to
select internal clock.
5
Rref
Connects to external reference resistor. Sets the operating frequency of the internal clock
and the ramp time for the PWM. Reference voltage at this pin is 1.26V.
6
Vid0
5-Bit DAC Input (LSB).
7
Vid1
5-Bit DAC Input.
8
Vid2
5-Bit DAC Input.
9
Vid3
5-Bit DAC Input.
10
Vid4
5-Bit DAC Input (MSB)
11
OC+
Over-current Comparator. Non-inverting input.
12
OC
Over-current Comparator. Inverting input.
13
COMP
Compensation Pin. This is the output of the internal transconductance amplifier.
Compensation network should be connected between this pin and feedback ground FBG.
14
FB
Feedback Input. Normally Kelvin connected to supply output.
15
Bgout
Current Limit Flag. Goes to logic low when current limit is activated. When over-current
condition is removed, this pin is weakly pulled up to Vcc5V.
16
FBG
Feedback Ground. This pin should be connected to the ground at the supply output.
17
ENABLE
Output Enable Pin. Tie to logic high to enable and logic low to disable.
18
GND
Power Ground Pin.
19
DRV2
Phase 2 Output.
20
DRV0
Phase 0 Output.
21
Vcc12V
Supply Voltage for FET Drivers DRV0:3.
22
DRV1
Phase 1 Output.
23
DRV3
Phase 3 Output.
24
PWRGD
Power Good. This is an open-drain output that goes low (low impedance to ground) when
the output voltage travels out of the threshold window, and resume to open-drain state when
V
OUT recovers into the 50mV hysteresis window. The power good window threshold, i.e.
±100mV for 1.3V
≤ V
OUT ≤ 1.9V or ±150mV for 2V ≤ VOUT ≤ 3.5V, is automatically set
according to VID code. Connect a 1nF capacitor to ground to filter out the switching noise
coupling from DRV3 to this pin.
LMS1
145
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