Datasheet

TPS40140
www.ti.com SLUS660H –SEPTEMBER 2005–REVISED JUNE 2013
4.3 VOLTAGE MASTER AND VOLTAGE SLAVE
A voltage master has the channel that monitors the output voltage and generates the 'COMP' signal for
voltage regulation. A Voltage slave channel is configured by connecting the TRKx pin to BP5. Then the
COMP signal from the master is connected to the COMPx pin on the Voltage slave. When the TRKx pin is
connected to BP5 the COMPx output for that channel is put in a high impedance state, allowing the
regulation for that channel to be controlled by the voltage master COMP signal.
4.3.1 TERMINAL FUNCTIONS
Table 4-1. TERMINAL FUNCTIONS
TERMINAL
I/O DESCRIPTION
NAME NO.
Filtered input from the VREG pin. A 10-Ω resistor should be connected between VREG and BP5 and a
BP5 8 I
1.0-μF ceramic capacitor should be connected from BP5 to ground.
GND 7 - Low noise ground connection to the device.
BOOT1 provides a bootstrapped supply for the high side FET driver for PWM1, enabling the gate of the
BOOT1 27 I high side FET to be driven above the input supply rail. Connect a capacitor from BOOT1 to SW1 pin and
a Schottky diode from this pin to VREG.
BOOT2 provides a bootstrapped supply for the high side FET driver for PWM2, enabling the gate of the
BOOT2 18 I high side FET to be driven above the input supply rail. Connect a capacitor from BOOT2 to SW2 pin and
a Schottky diode from this pin to VREG.
Digital clock signal for synchronizing slave controllers to the master CLKIO frequency and is either 6 or 8
CLKIO 28 O
times the PWM switching frequency.
COMP1 35 O Output of the error amplifier, CH1. The voltage at this pin determines the duty cycle for the PWM1.
COMP2 10 O Output of the error amplifier, CH2. The voltage at this pin determines the duty cycle for the PWM2.
These pins are used to sense the CH1 phase current. Inductor current can be sensed with an external
CS1 31 I current sense resistor or by using an external R-C circuit and the inductor’s DC resistance. The traces for
these signals must be connected directly at the current sense element.
These pins are used to sense the CH2 phase current. Inductor current can be sensed with an external
CS2 14 I current sense resistor or by using an external R-C circuit and the inductor’s DC resistance. The traces for
these signals must be connected directly at the current sense element.
Return point of CH1 current sense voltage. The trace for this signal must be connected directly at the
CSRT1 32 I
current sense element.
Return point of CH1 current sense voltage. The trace for this signal must be connected directly at the
CSRT2 13 I
current sense element.
Output of the differential amplifier. The output voltage of the differential amplifier is limited to 5.8 V. For
remote sensing, the voltage at this pin represents the true output voltage without I × R drops that result
DIFFO 1 O
from high current in the PCB traces. The VOUT and GSNS pins must be connected directly at the point of
load where regulation is required. See Layout Guidelines for more information.
Inverting input of the error amplifier for CH1. In closed loop operation, the voltage at this pin is nominally
FB1 36 I
700 mV. This pin is also monitored for PGOOD1 and undervoltage on CH1.
Inverting input of the error amplifier for CH2. In closed loop operation, the voltage at this pin is nominally
FB2 9 I
700 mV. This pin is also monitored for PGOOD2 and undervoltage on CH2.
Inverting input of the differential amplifier. This pin should be connected to ground at the load. If the
GSNS 3 I
differential amplifier is not used, tie this pin to GND or leave open.
Gate drive output for the high side N-channel MOSFET switch for CH1. Output is referenced to SW1 and
HDRV1 26 O
is bootstrapped for enhancement of the high side switch.
Gate drive output for the high side N-channel MOSFET switch for CH2. Output is referenced to SW2 and
HRDV2 19 O
is bootstrapped for enhancement of the high side switch.
Used to set the cycle-by-cycle current limit threshold for CH1. If the ILIM1 threshold is reached, the PWM
ILIM1 34 I
pulse is terminated and the converter delivers limited current to the output.
Used to set the cycle-by-cycle current limit threshold for CH2. If the ILIM2 threshold is reached, the PWM
ILIM2 11 I
pulse is terminated and the converter delivers limited current to the output.
LRDV1 24 O Gate drive output for the low side synchronous rectifier (SR) N-channel MOSFET for CH1.
LRDV2 22 O Gate drive output for the low side synchronous rectifier (SR) N-channel MOSFET for CH2.
Power good indicators for CH1 output voltage. This open-drain output connects to a voltage via an
PGOOD1 30 O
external resistor
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