FAN5099 Fairchild Semiconductor, FAN5099 Datasheet - Page 3

• Manufacturer Part Number: FAN5099
• Description: PWM and ULDO Controller Combo
• Manufacturer: Fairchild Semiconductor

FAN5099 Rev. 1.0.1
© 2006 Fairchild Semiconductor Corporation
Pin Assignment
Pin Description
Pin No. Pin Name
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
R(RAMP)
FBLDO
COMP
AGND
PGND
HDRV
BOOT
GLDO
LDRV
VCC
R(T)
ILIM
SW
SS
EN
FB
LDO Feedback. This node is regulated to V
Oscillator Set Resistor. This pin provides oscillator switching frequency adjustment. By plac-
ing a resistor (RT) from this pin to GND, the nominal 50kHz switching frequency is increased.
Current Limit. A resistor from this pin to GND sets the current limit.
Soft-Start. A capacitor from this pin to GND programs the slew rate of the converter and the
LDO during initialization. It also sets the time by which the converter delays when restarting
after a fault occurs. SS has to reach 1.2V before fault shutdown feature is enabled. The LDO
is enabled when SS reaches 2.2V.
COMP. The output of the error amplifier drives this pin.
Feedback. This pin is the inverting input of the internal error amplifier. Use this pin, in combi-
nation with the COMP pin, to compensate the feedback loop of the converter.
Enable. Enables operation when pulled to logic high. Toggling EN resets the regulator after a
latched fault condition. This is a CMOS input whose state is indeterminate if left open and
needs to be properly biased at all times.
Analog Ground. The signal ground for the IC. All internal control voltages are referred to this
pin. Tie this pin to the ground island/plane through the lowest impedance connection available.
Switching Node. Return for the high-side MOSFET driver and a current sense input. Connect
to source of high-side MOSFET and drain of low-side MOSFET.
High-Side Gate Drive Output. Connect to the gate of the high-side power MOSFETs. This
pin is also monitored by the adaptive shoot-through protection circuitry to determine when the
high-side MOSFET is turned off.
Bootstrap Supply Input. Provides a boosted voltage to the high-side MOSFET driver.
Connect to bootstrap capacitor as shown in Figure 1.
Power Ground. The return for the low-side MOSFET driver. Connect to source of low-side
MOSFET.
Low-Side Gate Drive Output. Connect to the gate of the low-side power MOSFETs. This pin
is also monitored by the adaptive shoot-through protection circuitry to determine when the
lower MOSFET is turned off.
Ramp Resistor. A resistor from this pin to VIN sets the ramp amplitude and provides voltage
feed-forward.
VCC. Provides bias power to the IC and the drive voltage for LDRV. Bypass with a ceramic
capacitor as close to this pin as possible. This pin has a shunt regulator which draws current
when the input voltage is above 5.6V.
Gate Drive for the LDO. Turned off (low) until SS is greater than 2.2V.
Figure 2. Pin Assignment
3
Pin Description
REF
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