RC5054AM 查看數據表（PDF） - Fairchild Semiconductor
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RC5054AM
Fairchild Semiconductor
RC5054AM Datasheet PDF : 13 Pages
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RC5054A
PRODUCT SPECIFICATION
age-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/µs slew rate which
enables high converter bandwidth for fast transient perfor-
mance. The resulting PWM duty ratio ranges from 0% to
100%.
The RC5054A 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 RC5054A
protects against over-current conditions by inhibiting PWM
operation. Built-in over-voltage protection triggers an exter-
nal SCR to crowbar the input supply. The RC5054A moni-
tors the current by using the RDS(ON) of the upper MOSFET
which eliminates the need for a current sensing resistor.
Pin Assignments
VSEN
OCSET
SS
VID0
VID1
VID2
VID3
VID4
COMP
FB
RC5054
(SOIC)
TOP VIEW
1
20
2
19
3
18
4
17
5
16
6
15
7
14
8
13
9
12
10
11
RT
OVP
VCC
LGATE
PGND
BOOT
UGATE
PHASE
PGOOD
GND
Pin Definitions
Pin Number Pin Names
1
VSEN
2
OCSET
Pin Function Description
This pin is connected to the converter’s output voltage. The PGOOD and OVP
comparator circuits use this signal to report output voltage status and for overvoltage
protection.
Connect a resistor (ROCSET) from this pin to the drain of the upper MOSFET.
ROCSET, an internal 200µA current source (IOCS), and the upper MOSFET on-
resistance (RDS(ON)) set the converter over-current (OC) trip point according to the
following equation:
IPEAK = I--O----C---R-S----D-•---S-R--(--OO----NC----)S----E---T-
An over-current trip cycles the soft-start function.
3
SS
Connect a capacitor from this pin to ground. This capacitor, along with an internal
10µA current source, sets the soft-start interval of the converter.
4-8
VID0-VID4 VID0-4 are the input pins to the 5-bit DAC. The states of these five 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 32 combinations of DAC inputs.
9
COMP COMP and FB are the available external pins of the error amplifier. The FB pin is the
10
FB
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.
11
GND Signal ground for the IC. All voltage levels are measured with respect to this pin.
12
PGOOD 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.
13
PHASE 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.
14
UGATE Connect UGATE to the upper MOSFET gate. This pin provides the gate drive for the
upper MOSFET.
15
BOOT This pin provides bias voltage to the upper MOSFET driver. A bootstrap circuit may
be used to create a BOOT voltage suitable to drive a standard N-Channel MOSFET.
16
PGND This is the power ground connection. Tie the lower MOSFET source to this pin.
2
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