TPS43335-Q1
TPS43336-Q1
SLVSAV6B –JUNE 2011–REVISED JULY 2012
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PIN FUNCTIONS (continued)
NAME NO. I/O DESCRIPTION
Enable input for BuckB (active-high with an internal pullup current source). An input voltage higher than 1.5 V
ENB 17 I enables the controller, whereas an input voltage lower than 0.7 V disables the controller. When both ENA and
ENB are low, the device is shut down and consumes less than 4 µA of current.
This input enables and disables the boost regulator. An input voltage higher than 1.5 V enables the controller.
Voltages lower than 0.7 V disable the controller. Because this pin provides and internal pulldown resistor (500 kΩ)
ENC 19 I it must be pulled high to enable the boost function. When enabled, the controller starts switching as soon as VBAT
falls below the boost threshold, depending upon the programmed output voltage.
EXTSUP can be used to supply the VREG regulator from one of the TPS43330/2 buck regulator rails to reduce
EXTSUP 37 I power dissipation in cases where VIN is expected to be high. When EXTSUP is open or lower than 4.6 V, the
regulator is powered from VIN.
Feedback voltage pin for BuckA. The buck controller regulates the feedback voltage to the internal reference of
FBA 12 I 0.8 V. A suitable resistor divider network between the buck output and the feedback pin sets the desired output
voltage.
Feedback voltage pin for BuckB. The buck controller regulates the feedback voltage to the internal reference of
FBB 27 I 0.8 V. A suitable resistor-divider network between the buck output and the feedback pin sets the desired output
voltage.
External high-side N-channel MOSFET for buck regulator BuckA can be driven from this output. The output
GA1 6 O provides high peak currents to drive capacitive loads. The gate drive is referred to a floating ground reference
provided by PHA and has a voltage swing provided by CBA.
External low-side N-channel MOSFET for buck regulator BuckA can be driven from this output. The output
GA2 8 O provides high peak currents to drive capacitive loads. The voltage swing on this pin is provided by VREG.
External high-side N-channel MOSFET for buck regulator BuckB can be driven from this output. The output
GB1 33 O provides high peak currents to drive capacitive loads. The gate drive is referred to a floating ground reference
provided by PHB and has a voltage swing provided by CBB.
External low-side N-channel MOSFETs for buck regulator BuckB can be driven from this output. The output
GB2 31 O provides high peak currents to drive capacitive loads. The voltage swing on this pin is provided by VREG.
An external low-side N-channel MOSFET for the boost regulator can be driven from this output. This output
GC1 3 O provides high peak currents to drive capacitive loads. The voltage swing on this pin is provided by VREG.
A floating output drive to control the external P-channel MOSFET is available at this pin. This MOSFET can be
GC2 4 O used to bypass the boost rectifier diode or a reverse protection diode when the boost is not switching or if boost is
disabled, and thus reduce power losses.
Open-drain power-good indicator pin for BuckA. An internal power-good comparator monitors the voltage at the
PGA 15 O feedback pin and pulls this output low when the output voltage falls below 93% of the set value, or if either Vin or
Vbat drops below its respective undervoltage threshold.
Open-drain power-good indicator pin for BuckB. An internal power-good comparator monitors the voltage at the
PGB 24 O feedback pin and pulls this output low when the output voltage falls below 93% of the set value, or if either Vin or
Vbat drops below its respective undervoltage threshold.
PGNDA 9 O Power ground connection to the source of the low-side N-channel MOSFETs of BuckA.
PGNDB 30 O Power ground connection to the source of the low-side N-channel MOSFETs of BuckB
Switching terminal of buck regulator BuckA, providing a floating ground reference for the high-side MOSFET gate-
PHA 7 O driver circuitry and used to sense current reversal in the inductor when discontinuous-mode operation is desired.
Switching terminal of buck regulator BuckB, providing a floating ground reference for the high-side MOSFET gate-
PHB 32 O driver circuitry and used to sense current reversal in the inductor when discontinuous-mode operation is desired.
The operating switching frequency of the buck and boost controllers is set by connecting a resistor to ground on
RT 22 O this pin. A short circuit to ground on this pin defaults operation to 400 kHz for the buck controllers and 200 kHz for
the boost controller.
SA1 10 I High-impedance differential voltage inputs from the current-sense element (sense resistor or inductor DCR) for
each buck controller. The current-sense element should be chosen to set the maximum current through the
inductor based on the current-limit threshold (subject to tolerances) and considering the typical characteristics
SA2 11 I across duty cycle and VIN. (SA1 positive node, SA2 negative node).
SB1 29 I High-impedance differential voltage inputs from the current-sense element (sense resistor or inductor DCR) for
each buck controller. The current-sense element should be chosen to set the maximum current through the
inductor based on the current-limit threshold (subject to tolerances) and considering the typical characteristics
SB2 28 I across duty cycle and VIN. (SB1 positive node, SB2 negative node).
Soft-start or tracking input for buck controller BuckA. The buck controller regulates the FBA voltage to the lower of
0.8 V or the SSA pin voltage. An internal pullup current source of 1 µA is present at the pin, and an appropriate
SSA 14 O capacitor connected here can be used to set the soft-start ramp interval. A resistor divider connected to another
supply can also be used to provide a tracking input to this pin.
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