MAX16930 Datasheet, PDF (11/29 Pages) Maxim Integrated Products – 2MHz, 36V, Dual Buck with Preboost and 20μA Quiescent Current

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MAX16930/MAX16931
2MHz, 36V, Dual Buck with Preboost and
20µA Quiescent Current
Pin Description (continued)
NAME
EXTVCC
IN
PGOOD1
FB3
INS
CS3P
CS3N
TERM
DL3
PGND3
PGOOD2
N.C.
FSYNC
FOSC
COMP2
FB2
DESCRIPTION
3.1V to 5.2V Input to the Switchover Comparator
Supply Input. Connect IN to the output of the preboost. Bypass IN with sufficient capacitance to
supply the two out-of-phase buck converters.
Open-Drain Power-Good Output for Buck 1. PGOOD1 is low if OUT1 is more than 15% (typ) below
the normal regulation point. PGOOD1 asserts low during soft-start and in shutdown. PGOOD1
becomes high impedance when OUT1 is in regulation. To obtain a logic signal, pullup PGOOD1 with
an external resistor connected to a positive voltage lower than 5.5V.
Preboost Feedback Input. Connect FB3 to the center tap of a resistive-divider between the boost
regulator output and TERM to adjust the output voltage. FB3 regulates to 1.25V (typ). See the Setting
the Output Voltage in Boost Converter section.
Input Voltage Sense for Preboost. The voltage at INS is compared to internal comparator reference.
Program the preboost threshold by using resistor-divider from BAT to INS to TERM pin.
Positive Current-Sense Input for Preboost. Connect CS3P to the positive terminal of the current-
sense resistor. See the Current Limit in Boost Controller and Shunt Resistor Selection in Boost
Converter sections.
Negative Current-Sense Input for Preboost. Connect CS3N to the negative terminal of the current-
sense resistor. See the Current Limit in Boost Controller and Shunt Resistor Selection in Boost
Converter sections.
Ground Switch. TERM opens when the voltage at EN3 is logic-low. Use TERM to terminate the
preboost feedback and INS resistive divider.
Preboost n-Channel MOSFET Gate-Drive Output
Power Ground for Preboost. All the high-current paths for the preboost should terminate to this
ground.
Open-Drain Power-Good Output for Buck 2. PGOOD2 is low if OUT2 is more than 90% (typ) below
the normal regulation point. PGOOD2 asserts low during soft-start and in shutdown. PGOOD2
becomes high impedance when OUT2 is in regulation. To obtain a logic signal, pullup PGOOD2 with
an external resistor connected to a positive voltage lower than 5.5V.
No Connection
External Clock Synchronization Input. Synchronization to the controller operating frequency ratio is
1. Keep f_SYNC a minimum of 10% greater than the maximum internal switching frequency for stable
operation. See the Switching Frequency/External Synchronization section.
Frequency Setting Input. Connect a resistor from FOSC to AGND to set the switching frequency of
the DC-DC converters.
Buck 2 Error Amplifier Output. Connect an RC network to COMP2 to compensate buck 2.
Feedback Input for Buck 2. Connect FB2 to BIAS for the 3.3V fixed output or to a resistive divider
between OUT2 and GND to adjust the output voltage between 1V and 10V. In adjustable mode, FB2
regulates to 1V (typ). See the Setting the Output Voltage in Buck Converters section.
Maxim Integrated
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