
RC5039
PRODUCT SPECIFICATION
2
P
Pin Assignments
Pin Definitions
Pin Number
1
Pin Name
OCSET
Pin Function Description
Connect a resistor (R
OCSET
) from this pin to the drain of the upper MOSFET.
R
OCSET
, an internal 200
m
A current source (I
OCS
), and the upper MOSFET
on-resistance. (R
DS(ON)
) set the converter over-current (OC) trip point according
to the following equation:
An over-current trip cycles the soft-start function.
Connect a capacitor from this pin to ground. This capacitor, along with an internal
10
m
A current source, sets the soft-start interval of the converter.
VID0-3 are the input pins to the 4-bit DAC. The states of these four pins program the
internal voltage reference (DACOUT). The level of DACOUT sets the converter
output voltage. It also sets the PGOOD and OVP thresholds. Table 1 specifies
DACOUT for the 16 combinations of DAC inputs.
COMP and FB are the available external pins of the error amplifier. The FB pin is the
inverting input of the error amplifier and the COMP pin is the error amplifier output.
These pins are used to compensate the voltage-control feedback loop of the
converter.
Signal ground for the IC. All voltage levels are measured with respect to this pin.
PGOOD is an open collector output used to indicate the status of the converter output
voltage. This pin is pulled low when the converter output is not within
±
10% of the
DACOUT reference voltage.
Connect the PHASE pin to the upper MOSFET source. This pin is used to monitor the
voltage drop across the MOSFET for over-current protection. This pin also provides
the return path for the upper gate drive.
Connect UGATE to the upper MOSFET gate. This pin provides the gate drive for the
upper MOSFET.
2
SS
3-6
VID0-3
7
8
COMP
FB
9
10
GND
PGOOD
11
PHASE
12
UGATE
RC5039 (SOIC)
TOP VIEW
OCSET
SS
VID0
VID1
VID2
VID3
FB
COMP
VSEN
VCC
BOOT
UGATE
PHASE
PGOOD
GND
RT/OVP
1
2
3
4
5
7
6
8
14
15
16
9
13
12
11
10
I
PEAK
I
---------R
R
DS ON
·
)
=
The RC5039 provides simple, single feedback loop, voltage-
mode control with fast transient response. It includes a
200kHz free-running triangle-wave oscillator that is adjust-
able from 50kHz to 1MHz. The error amplifier features a
15MHz gain-bandwidth product and 6V/
m
s slew rate which
enables high converter bandwidth for fast transient perfor-
mance. The resulting PWM duty ratio ranges from 0% to
100%.
The RC5039 monitors the output voltage with a window
comparator that tracks the DAC output and issues a Power
Good signal when the output is within
±
10%. The RC5039
monitors the current by using the R
DS(ON)
of the upper
MOSFET which eliminates the need for a current sensing
resistor. The RC5039 protects against over-current condi-
tions by inhibiting PWM operation. Built-in over-voltage
protection triggers an exter-nal SCR to crowbar the input
supply.