XRP7708 Exar Corporation, XRP7708 Datasheet
XRP7708
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XRP7708 Summary of contents
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... February 2010 GENERAL DESCRIPTION The XRP7708 is a quad-output pulse-width modulated (PWM) step-down DC-DC controller with a built-in LDO for standby power and GPIOs. The device provides a complete power management solution in one IC and is fully 2 programmable via serial interface. Independent Digital Pulse Width Modulator ...
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... VOUT Regulation Accuracy VOUT regulation range VOUT set point resolution VOUT set point resolution VOUT Input Current VOUT Input Resistance Load Current Note 1: Voltages above 5.1V can be obtained by using an external voltage divider. Low Drop-out Regulator © 2010 Exar Corporation ...
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... Output Pin Low Level Output Pin High Level Output Pin High Level (no load Specification Parameter Speed Input Pin Low Level Input Pin High Level Hysteresis of Schmitt Trigger Inputs, V HYS © 2010 Exar Corporation ...
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... Capacitance for each I/O Pin Note the capacitance one one bus Gate Drivers Parameter GH, GL Rise and Fall Time GH, GL Pull-up On-State Output Resistance GH, GL Pull-down On-State Output Resistance GH, GL Pull-down Off-State Output Resistance © 2010 Exar Corporation ...
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... Exar Corporation Fig. 2: XRP7708 Block Diagram 5/ ...
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... Fig. 3: XRP7708 Pin Assignment Power source for the internal linear regulators to generate VCCA, VDD and the Standby LDO (LDOOUT). Place a decoupling capacitor close to the controller IC. Also used in UVLO1 fault generation – if VIN1 falls below the user programmed limit, all channels are shut down ...
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... Application Note]. If ENABLE is pulled high, the chip powers up (logic reset, registers configuration loaded, etc.). If pulled low for longer than 100us, the XRP7708 is placed into shutdown. Analog Ground. Connect to analog ground (as noted above for pin 11). ...
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... Channels not in use are disabled FET: Si4944; Inductor: 744314xxx 7x7x5mm Fig. 6: 12Vin Efficiency: Single Channel 300kHz - Channels not in use are disabled FET: FDS8984; Inductor:744310200 7x7x3mm Fig. 8: Simultaneous Start-up Configuration CH1:3.3V CH2:5V CH3:1V CH4:1.8V © 2010 Exar Corporation ...
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... Fig. 10: Sequential Start-up Configuration CH1:3.3V CH2:5V CH3:1V CH4:1.8V Fig. 12: Startup into 3V prebias – 5V Output CH1: Vout(5V) Fig. 14: Load Transient Response CH1:Iout (1A/div) CH2: Vout (3.3V) © 2010 Exar Corporation ...
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... Fig. 15: Temperature Regulation 1.8V out (+/- 1% Vo window) © 2010 Exar Corporation Fig. 16: Temperature Regulation 1.0V out (+/- 1% Vo window) 10/ ...
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... Reliability is enhanced via communication with the system controller which can obtain real time data on an output voltage, input voltage and current. • System XRP7708 directly to obtain data or make adjustments use). Pins can to react to circuit conditions • A system process or could also be configured to log ...
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... The chip also provides over-temperature protection (OTP) and under-voltage lock-out (UVLO) for two input voltage rails. The XRP7708 also has GPIOs and a Standby Linear Regulator to provide standby power communicate with the host for fault reporting and handling, power rail monitoring, channel enable and disable, Standby Low Drop-out Regulator voltage reconfiguration, and Standby LDO enable and disable ...
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... NABLING ISABLING AND The XRP7708 is enabled via raising the ENABLE Pin high. lowering the same ENABLE Pin. SOFTRESET Command. For enabling a specific channel, there are several ways that this can be achieved. The chip can be configured to enable a channel at start-up as the default configuration residing in the non-volatile configuration memory of the IC. The channels can also be enabled using GPIO pins and/ © ...
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... This fault condition will be indicated in the READ_FAULT_WARN register. When an under voltage fault condition occurs (either on VIN1 or VIN2), the fault flag register is set and all of the XRP7708 outputs are shut down. The measured input voltages can be read back using the READ_VIN1 or READ_VIN2 register, and both registers have a resolution of 100mV per LSB ...
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... The output voltage regulation in this case might exceed 2% due to extra error from the resistor divider. R1 and R2 follows the definition below. Fig. 18: External divider network for high output voltage © 2010 Exar Corporation ...
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... Output Voltage Lower Than 0.9V The XRP7708 can be programmed to regulate an output voltage lower than 0.9V. However, in this case the specification of +-2% output voltage accuracy may be exceeded VER OLTAGE ROTECTION The Over-Voltage Protection (OVP) SET_OVVP_REGISTER sets the over-voltage condition in predefined steps per channel. The over-voltage protection is always active even during soft-start condition ...
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... The XRP7708 also offers an Over-Current warning flag. This warning flag resides in the READ_OVC_FLAG register. The warning flag bit will be set when the output current gets to within a specified value of the output current limit threshold enabling the host to reduce power consumption. The SET_VIOUT_MAX_CHx register allows the warning flag threshold to be set 10mV, 20mV, 30mV or 40mV below VIOUT_MAX ...
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... G F OWER OOD LAG The XRP7708 allows the user to set the upper and lower bound for a power good signal per channel. The SET_PWRG_TARG_MAX_CHx SET_PWRG_TARG_MIN_CHx register sets the lower bound. Each register has a 20mV LSB resolution. When the output voltage is within bounds the power good signal is asserted high. ...
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... The maximum duty cycle is dictated by the minimum required time to sample the current when the low side MOSFET is on. For the XRP7708, the minimum required sampling time is about 16 clock cycles at the main oscillator frequency. When calculating maximum duty cycle, the sampling time needs to be subtracted using the below equation ...
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... S REQUENCY YNCHRONIZATION The user of the XRP7708 can choose to use an external source as the primary clock for the XRP7708. This function can be configured using the SET_SYNC_MODE_CONFIG register. This register sets the operation of the XRP7708 when an external clock is required. By selecting the appropriate bit combination the user can configure the IC to function as a master or a slave when two or more XRP7708s are used to convert power in a system ...
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... CLK_OUT CLK_IN GPIO1 SYNC_OUT SYNC_IN GPIO2 XRP7708 configured as a master Fig. 23: Master/Slave Configuration of the XRP7708 There are two ways of synchronizing this, GPIO1 SYNC_OUT GPIO2 XRP7708 Configured as a master with external clock sync CLK_OUT GPIO3 GPIO1 SYNC_OUT GPIO2 XRP7708 ...
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... GPIO P INS The General Purpose Input Output (GPIO) Pins are the basic interface between the XRP7708 and the system. Although all of the stored data within the IC can be read back using the I sometimes convenient to have some of those internal register to be displayed and or controlled by a single data pin ...
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... Use the following equation to calculate Cout: Where the output inductance I2 is the step load high current I1 is the step load low current Vos is output voltage including the overshoot Vout is the steady state output voltage Or it can be expressed approximately by © 2010 Exar Corporation ...
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... In general, the total input voltage ripple should be kept below 1.5% of VIN. The input voltage ripple also has two major components: the voltage drop on the main capacitor voltage drop due to ESR - calculated from: Total input voltage ripple is the sum of the above: © 2010 Exar Corporation ...
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... Selecting MOSFETs with lower Rdson reduces conduction losses at the expense of increased switching losses. A simplified expression for conduction losses is given by: MOSFET’s junction temperature can be estimated from: This assumes that the switching loss is the same as the conduction loss. thermal resistance from junction to ambient. © 2010 Exar Corporation ...
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... PACKAGE SPECIFICATION 40 TQFN IN MMX MM © 2010 Exar Corporation 26/ ...
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... While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized ...