Datasheet LTC7060 (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | 100V Half Bridge Driver with Floating Grounds and Programmable Dead-Time |
| Pages / Page | 18 / 10 — OPERATION OUTPUT STAGE. PROTECTION CIRCUITRY. Figure 2. Simplified Output … |
| File Format / Size | PDF / 1.4 Mb |
| Document Language | English |
OPERATION OUTPUT STAGE. PROTECTION CIRCUITRY. Figure 2. Simplified Output Stage in Half Bridge Configuration
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link to page 10 link to page 10 LTC7060
OPERATION OUTPUT STAGE
produce a rapid turn-on transition for the MOSFETs with A simplified version of the LTC7060’s output stage is capability of driving a 3.3nF load with 18ns rise time. shown in Figure 2. The BG and TG design are symmetric Furthermore, a strong pul -down on the driver outputs and they both have floating gate driver outputs. The pull- prevents cross-conduction current. For example, in the up device is a PMOS with a typical 1.5Ω RDS(ON) and the half bridge configuration shown in Figure 2, when BG pull-down device is a NMOS with a typical 0.8Ω RDS(ON). turns the low side power MOSFET off and TG turns the The wide driver supply voltage ranging from 4V to 14V high side power MOSFET on, the voltage on the SW pin enables the driving of different power MOSFETs, such as could rise to V logic level or higher threshold MOSFETs. However, the IN very rapidly. This high frequency posi- tive voltage transient will couple through the C LTC7060 is optimized for higher threshold MOSFETs (e.g. GD capaci- tance of the low side power MOSFET to the BG pin. If the BST-SW = 10V and BGVCC-BGRTN = 10V). The driver out- BG pin is not held down sufficiently, the voltage on the put pull-up and pull-down resistance may increase with BG pin could rise above the threshold voltage of the low lower driver supply voltage. side power MOSFET, momentarily turning it back on. As VIN a result, both the high side and low side MOSFETs would LTC7060 BST be conducting, which would cause significant cross-con- duction current to flow through the MOSFETs from VIN 1.5Ω CGD to ground, thereby incurring substantial power loss and TG HIGH SIDE potentially damaging the MOSFETs. For this reason, short POWER MOSFET PCB traces for the BG and TG pins, which minimize the C 0.8Ω GS parasitic inductances, are recommended. SW
PROTECTION CIRCUITRY
BGVcc When using the LTC7060, care must be taken not to exceed any of the ratings specified in the Absolute 1.5Ω CGD Maximum Ratings section. As an added safeguard, the BG LOW SIDE POWER MOSFET LTC7060 incorporates overtemperature shutdown fea- C 0.8Ω GS ture. If the junction temperature reaches approximately BGRTN 180°C, the LTC7060 will enter thermal shutdown mode and BG will be pulled to BGRTN; TG will be pulled to SW. Normal operation will resume when the junction tempera- 7060 F02 ture cools down below 165°C. The overtemperature level
Figure 2. Simplified Output Stage in Half Bridge Configuration
is not production tested. The LTC7060 is guaranteed to Since the power MOSFETs general y account for the operate below 150°C. majority of the power loss in a converter, it is important to turn them on and off quickly, thereby minimizing the The LTC7060 contains both undervoltage and overvoltage transition time and power loss. The LTC7060’s typical lockout detectors that monitor the VCC supply. When VCC 1.5Ω pull-up resistance and 0.8Ω pull-down resistance falls below 5.3V or rises above 14.6V, BG and TG pins are are equivalent to 3A peak pull-up current and 6A peak pull pulled to BGRTN and SW, respectively, turning off both down current at a 10V driver supply. Both BG and TG can the external MOSFETs. When VCC has adequate supply voltage but less than the overvoltage threshold, normal operation will resume. Rev. 0 10 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Timing Diagram Operation Applications InformatioN Typical Applications Package Description Typical Application Related Parts
OPERATION OUTPUT STAGE
produce a rapid turn-on transition for the MOSFETs with A simplified version of the LTC7060’s output stage is capability of driving a 3.3nF load with 18ns rise time. shown in Figure 2. The BG and TG design are symmetric Furthermore, a strong pul -down on the driver outputs and they both have floating gate driver outputs. The pull- prevents cross-conduction current. For example, in the up device is a PMOS with a typical 1.5Ω RDS(ON) and the half bridge configuration shown in Figure 2, when BG pull-down device is a NMOS with a typical 0.8Ω RDS(ON). turns the low side power MOSFET off and TG turns the The wide driver supply voltage ranging from 4V to 14V high side power MOSFET on, the voltage on the SW pin enables the driving of different power MOSFETs, such as could rise to V logic level or higher threshold MOSFETs. However, the IN very rapidly. This high frequency posi- tive voltage transient will couple through the C LTC7060 is optimized for higher threshold MOSFETs (e.g. GD capaci- tance of the low side power MOSFET to the BG pin. If the BST-SW = 10V and BGVCC-BGRTN = 10V). The driver out- BG pin is not held down sufficiently, the voltage on the put pull-up and pull-down resistance may increase with BG pin could rise above the threshold voltage of the low lower driver supply voltage. side power MOSFET, momentarily turning it back on. As VIN a result, both the high side and low side MOSFETs would LTC7060 BST be conducting, which would cause significant cross-con- duction current to flow through the MOSFETs from VIN 1.5Ω CGD to ground, thereby incurring substantial power loss and TG HIGH SIDE potentially damaging the MOSFETs. For this reason, short POWER MOSFET PCB traces for the BG and TG pins, which minimize the C 0.8Ω GS parasitic inductances, are recommended. SW
PROTECTION CIRCUITRY
BGVcc When using the LTC7060, care must be taken not to exceed any of the ratings specified in the Absolute 1.5Ω CGD Maximum Ratings section. As an added safeguard, the BG LOW SIDE POWER MOSFET LTC7060 incorporates overtemperature shutdown fea- C 0.8Ω GS ture. If the junction temperature reaches approximately BGRTN 180°C, the LTC7060 will enter thermal shutdown mode and BG will be pulled to BGRTN; TG will be pulled to SW. Normal operation will resume when the junction tempera- 7060 F02 ture cools down below 165°C. The overtemperature level
Figure 2. Simplified Output Stage in Half Bridge Configuration
is not production tested. The LTC7060 is guaranteed to Since the power MOSFETs general y account for the operate below 150°C. majority of the power loss in a converter, it is important to turn them on and off quickly, thereby minimizing the The LTC7060 contains both undervoltage and overvoltage transition time and power loss. The LTC7060’s typical lockout detectors that monitor the VCC supply. When VCC 1.5Ω pull-up resistance and 0.8Ω pull-down resistance falls below 5.3V or rises above 14.6V, BG and TG pins are are equivalent to 3A peak pull-up current and 6A peak pull pulled to BGRTN and SW, respectively, turning off both down current at a 10V driver supply. Both BG and TG can the external MOSFETs. When VCC has adequate supply voltage but less than the overvoltage threshold, normal operation will resume. Rev. 0 10 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Timing Diagram Operation Applications InformatioN Typical Applications Package Description Typical Application Related Parts
