2121 Switched mode DC/DC-converter CCITT ISDN compatible power di
|
|
|
Top Searches for this datasheet
General-Purpose Power Controller (GPPC)
2121
Switched mode DC/DC-converter CCITT ISDN compatible power dissipation Supply voltage range Programmable input undervoltage protection Programmable overcurrent protection Soft start Power housekeeping input Oscillator synchronization input/output High voltage CMOS-technology
P-DSO-20-1
P-DIP-16
Type 2121-P 2121-T
Version A4/A5 A4/A5
Ordering Code Q67100-H8646 Q67100-H6032
Package P-DIP-16 P-DSO-20-1 (SMD)
2121 pulse width modulator circuit designed fixed-frequency switching regulators with very power consumption. telephony ISDN systems high conversion yield crucial maintain functionality supply conditions interfaces. 2121 design technology realize high conversion efficiency power dissipation. should recognized that 2121 also used numerous DC/DC-conversion systems other than ISDN-power supplies.
Semiconductor Group
12.92
2121
2121 Contains Following Functional Blocks
Undervoltage lockout Temperature compensated voltage reference Sawtooth oscillator Error amplifier Pulse width modulator Digital current limiting Soft start Double pulse inhibit Power driver
Together with external components provides stable DC-supply subscriber terminals (TEs) network terminations (NTs). also programmed higher output voltages, e.g. supply S-lines with
Configurations (top view) P-DSO-20 P-DIP-16
Semiconductor Group
2121
Definitions Functions Symbol Input P-DSO P-DIP Output Definition Reference voltage Positive current sense Negative current sense Ground Gate Function Output reference voltage. When voltage difference between these pins exceeds digital current limiting becomes active. analog digital signals referred this pin. Totem-pole output driver, connected with gate external power switch. Output internal CMOS supply. VEXT internal CMOScircuits supplied from external DC-supply order reduce chip power dissipation. capacitor this determines soft start characteristic.
VREF
VEXT
External supply
PWMP
Soft start capacitor Battery voltage Pulse width modulator Positive voltage sense Negative voltage sense Undervoltage detection
positive input voltage.
Non-inverting input pulse width modulator. Error amplifier output. Non-inverting input error amplifier. Inverting input error amplifier. undervoltage lockout programmed
SYNC
Synchronization This used input synchronization oscillator external frequency, output synchronize multiple devices. R-oscillator C-oscillator external timing components ramp generator attached
Semiconductor Group
2121
Figure GPPC Functional Diagram
Semiconductor Group
2121
Absolute Maximum Ratings Parameter Supply voltage (pin referred Analog input voltage (pins PWMP, SYNC, referred Reference output current (pin VREF) SYNC output current (pin SYNC) Error amplifier output current (pin Z-current (pin VEXT) Output current (pin VEXT) Driver output current (pin Ambient temperature under bias Storage temperature Symbol Limit Values Unit
SYNC Tstg
DC-Characteristics Limit Values Parameter Supply current Reference VREF Output voltage Symbol min. typ. max. Unit Test Condition
VREF
3.92
4.08
Line regulation
VREF Line
Load regulation
VREF Load
Temperature stability Load current
VREF IREF Load
Semiconductor Group
2121
DC-Characteristics (cont'd) Limit Values Parameter Symbol min. typ. max. Unit Test Condition
Oscillator SYNC fOSC kHz, Initial accuracy Voltage stability Temperature stability Max. frequency Sawtooth peak voltage Sawtooth valley voltage H-sync output level L-sync output level Error Amplifier Input offset voltage Input current Common mode range open loop gain Common mode rejection Unity gain bandwidth Supply voltage rejection H-output voltage L-output voltage 5.25
fmax VSYNC VSYNC
VEXT
kCMR kSVR
0.02
(pin)
Current Limit Comparator
Sense voltage Input bias current Input voltage range Response time (signal
VSense tRes
Semiconductor Group
2121
DC-Characteristics (cont'd) Limit Values Parameter Pulse Width Modulator Duty cycle Under Voltage Detection Start threshold Threshold hysteresis Soft Start Charging current Output Driver Symbol min. typ. max. Unit Test Condition
H-output voltage L-output voltage Rise time Fall time Output current External Supply VEXT Output voltage Output current Input voltage Z-current Power consumption
VEXT
ISource ISink VEXT VEXT
Ptot
fOSC VEXT
Semiconductor Group
2121
Application Informations Undervoltage Lockout undervoltage lockout circuit protects 2121 power devices from inadequate supply voltage. low, circuit disables this output driver. This ensures that control functions have been stabilized proper state when turn voltage reached, prevents from possibility start glitches. undervoltage lockout programmable connecting Z-diode between from connected default undervoltage lockout Voltage Reference reference regulator 2121 based temperature compensated bandgap. This circuitry fully active supply voltages above volts provides load current external circuitry volts. This reference buffered external capacitor Oscillator oscillator frequency programmed three components: shown figure oscillator timing capacitor charged VREF through discharged seriesconnected with internal discharge-resistor.) rise-time fall-time sawtooth oscillator programmed individually.
Figure
Semiconductor Group
2121
beginning discharge period positive synchronization pulse generated SYNC. Otherwise 2121 synchronized SYNC external logic clock programming oscillator free frequency lower than synchronization frequency. 2121 synchronized rising edge sync. signal. multiple devices synchronized together programming master unit desired frequency. Notice that frequency output driver half oscillator frequency. switching frequency function with shown figure
Figure Switching Frequency Soft Start Circuit soft start circuit protects power transistors rectifier diodes from high current surges during power supply turn-on. When supply voltage connected 2121 undervoltage lockout circuit holds soft start capacitor voltage zero. When supply voltage reaches normal operating range internal current source will charge external soft start capacitor. soft start voltage ramps volts, duty cycle linearly increases whatever value regulation loop requires.
Semiconductor Group
2121
Pulse Width Modulator pulse width modulator compares sawtooth-voltage oscillator output with input signal PWMP with voltage external soft start capacitor (see figure Error Amplifier Conventional operational amplifier closed-loop gain phase compensation. output impedance: unity-gain stable Control Logic control logic inhibits double pulses during duty cycle limits maximum duty cycle Current Limiting differential input comparator terminates individual output pulses each time when sensvoltage rises above threshold. When sense voltage rises above threshold shutdown signal sent control logic. CMOS Supply integrated linear voltage regulator supplies internal low-voltage CMOS-circuits from input voltage. This supply-voltage connected VEXT buffered external capacitor (Cmin µF). Power dissipation linear voltage regulator reduced, external supply used that purpose connecting VEXT. input voltage VEXT reaches internal linear voltage regulator turns internal CMOS-circuits from external voltage. this case input current VEXT approx. Note: internal Z-diode protects VEXT input against overvoltage. maximum Z-current external CMOS-supply isn't stabilized input current must limited resistor).
Semiconductor Group
2121
Extended Input Voltage Range Some DC/DC-converter applications require higher input voltage than maximum supply voltage 2121 which limited Figure shows method extend input voltage range connecting zener-diode between input voltage 2121.
Figure 2121 VEXT, input current approx. additional power losses accordingly minimum input voltage 2121 Applications 2121 accommodates both galvanically isolated non-isolated configurations. Figure shows non-isolated flyback converter. converter fully compatible with CCITT-power recommendations S-interface. input voltage efficiency input power input power Figure shows flyback converter with opto isolation feed S-bus with maximum input voltage extended from
Semiconductor Group
2121
Figure Application Circuit Semiconductor Group
2121
Figure Application Circuit Semiconductor Group
Other recent searches
VSC9112 - VSC9112 VSC9112 Datasheet
S66ZOV231HC - S66ZOV231HC S66ZOV231HC Datasheet
PHB130N03L - PHB130N03L PHB130N03L Datasheet
NE556 - NE556 NE556 Datasheet
SA556 - SA556 SA556 Datasheet
SE556 - SE556 SE556 Datasheet
EPA2127A - EPA2127A EPA2127A Datasheet
Privacy Policy | Disclaimer
© 2012 Datasheet Archive
