The TPS92640 and TPS92641 devices are high-voltage, synchronous NFET controllers for buck-current regulators. Output current regulation is based on valley current-mode operation using a controlled on-time architecture. This control method eases the design of loop compensation while maintaining nearly constant switching frequency. The TPS92640 and TPS92641 devices include a high-voltage start-up regulator that operates over a wide input range of 7 V to 85 V. The PWM controller is designed for high speed capability, including an oscillator frequency range up to 1 MHz. The deadtime between high side and low side gate driver is optimized to provide very high efficiency over a wide input operating voltage and output power range. The TPS92640 and TPS92641 devices accept both analog and PWM input signals, resulting in exceptional dimming control range. Linear response characteristics between input command and LED current is achieved with true zero LED current using low off-set error amplifier and proprietary PWM dimming logic. Both devices also include precision reference capable of supplying current to low power microcontroller. Protection features include cycle-by-cycle current protection, overvoltage protection, and thermal shutdown. The TPS92641 device includes a shunt FET dimming input and MOSFET driver for high resolution PWM dimming.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
TPS92640 | HTSSOP (14) | 4.40 mm × 5.00 mm |
TPS92641 | HTSSOP (16) | 4.40 mm × 5.00 mm |
Changes from * Revision (October 2012) to A Revision
PIN | I/O | DESCRIPTION | ||
---|---|---|---|---|
NAME | NO. (TPS92640) | NO. (TPS92641) | ||
BOOT | 12 | 14 | O | Connect 100-nF ceramic capacitor to switch node and diode to VCC to provide boosted voltage for high-side gate drive. |
COMP | 7 | 7 | O | Connect ceramic capacitor to GND to set loop compensation. |
CS | 9 | 11 | I | Connect to positive terminal of sense resistor at the bottom of the LED stack. |
GND | 8 | 10 | — | System GND. Connect to DAP. |
HG | 14 | 16 | O | Connect to gate of high-side NFET of buck regulator. Use series resistor to limit current slew-rate and mitigate EMI noise. |
IADJ | 6 | 6 | I | Connect resistor divider from VREF to set analog dimming level. Use NTC resistor from pin to GND as resistor divider to implement thermal foldback operation. |
LG | 10 | 12 | O | Connect to gate of low-side NFET of buck regulator. Use series resistor to limit current slew-rate and mitigate EMI noise. |
RON | 2 | 2 | I | Connect a resistor to VIN and capacitor to GND to set switching frequency. |
SDIM | — | 8 | I | PWM dimming input for shunt FET dimming. |
SDRV | — | 9 | O | Connect to gate of external parallel NFET across LED load used for shunt dimming if desired. |
SW | 13 | 15 | O | Connect to switch node of buck regulator. |
UDIM | 3 | 3 | I | Connect resistor divider from VIN to set undervoltage lockout threshold. |
VCC | 11 | 13 | O | Bypass with 2.2-µF ceramic capacitor to provide bias supply for controller. |
VIN | 1 | 1 | I | Connect to input voltage. Connect 1-µF bypass capacitor |
VOUT | 4 | 4 | I | Connect resistor divider from VOUT, scaled down feedback of VOUT. |
VREF | 5 | 5 | O | System reference voltage. Bypass with 100-nF ceramic capacitor. |
DAP | — | — | — | Place 6-9 vias from pad to GND plane for thermal relief. |