UCC39421

ACTIVE

High frequency multimode synchronous controller with optimized efficiency

Data sheet

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UCC39421

ACTIVE

Data sheet

Product details

Rating

Catalog

Topology

Boost, Flyback, SEPIC

Iout (max) (A)

1

Vin (max) (V)

8

Vin (min) (V)

1.5

Vout (max) (V)

8

Vout (min) (V)

2.5

Control mode

Peak current mode, Voltage mode

Features

Enable, Frequency synchronization, Light-load efficiency

Operating temperature range (°C)

0 to 70

Iq (typ) (µA)

635

Duty cycle (max) (%)

100

Rating

Catalog

Topology

Boost, Flyback, SEPIC

Iout (max) (A)

1

Vin (max) (V)

8

Vin (min) (V)

1.5

Vout (max) (V)

8

Vout (min) (V)

2.5

Control mode

Peak current mode, Voltage mode

Features

Enable, Frequency synchronization, Light-load efficiency

Operating temperature range (°C)

0 to 70

Iq (typ) (µA)

635

Duty cycle (max) (%)

100

Operation Down to an Input Voltage of 1.8 V
High Efficiency Boost, SEPIC or Flyback (Buck-Boost) Topologies
Drives External FETs for High-Current Applications
Up to 2-MHz Oscillator
Synchronizable Fixed Frequency Operation
High-Efficiency Low-Power Mode
High-Efficiency at Very Low-Power with Programmable Variable Frequency Mode
Pulse-by-Pulse Current Limit
5-µA Supply Current in Shutdown
150-µA Supply Current in Sleep Mode
Selectable NMOS or PMOS Rectification
Built-In Power-On Reset (UCC39422 Only)
Built-In Low-Voltage Detect (UCC39422 Only)

Operation Down to an Input Voltage of 1.8 V
High Efficiency Boost, SEPIC or Flyback (Buck-Boost) Topologies
Drives External FETs for High-Current Applications
Up to 2-MHz Oscillator
Synchronizable Fixed Frequency Operation
High-Efficiency Low-Power Mode
High-Efficiency at Very Low-Power with Programmable Variable Frequency Mode
Pulse-by-Pulse Current Limit
5-µA Supply Current in Shutdown
150-µA Supply Current in Sleep Mode
Selectable NMOS or PMOS Rectification
Built-In Power-On Reset (UCC39422 Only)
Built-In Low-Voltage Detect (UCC39422 Only)

The UCC39421 family of synchronous PWM controllers is optimized to operate from dual alkaline/NiCd cells or a single Lithium-Ion (Li-Ion) cell, and convert to adjustable output voltages from 2.5 V to 8 V. For applications where the input voltage does not exceed the output, a standard boost configuration is used.

For other applications where the input voltage can swing above and below the output, a 1:1 coupled inductor (Flyback or SEPIC) is used in place of the single inductor. Fixed frequency operation can be programmed, or synchronized to an external clock source. In applications where (at light loads) variable frequency mode is acceptable, the IC can be programmed to automatically enter PFM (pulse frequency modulation) mode for an additional efficiency benefit.

Synchronous rectification provides excellent efficiency at high power levels, where N- or P- type MOSFETs can be used. At lower power levels (between 10% and 20% of full load) where fixed frequency operation is required, low power mode is entered. This mode optimizes efficiency by cutting back on the gate drive of the charging FET. At very low power levels, the IC enters a variable frequency mode (PFM). PFM can be disabled by the user.

Other features include pulse-by-pulse current limiting, and a low 5-µA quiescent current during shutdown. The UCC39422 incorporates programmable power-on reset circuitry and an uncommitted comparator for low voltage detection. The available packages are 20-pin TSSOP or 20-pin N for the UCC39422, and 16-pin TSSOP or 16-pin N for the UCC39421.

The UCC39421 family of synchronous PWM controllers is optimized to operate from dual alkaline/NiCd cells or a single Lithium-Ion (Li-Ion) cell, and convert to adjustable output voltages from 2.5 V to 8 V. For applications where the input voltage does not exceed the output, a standard boost configuration is used.

For other applications where the input voltage can swing above and below the output, a 1:1 coupled inductor (Flyback or SEPIC) is used in place of the single inductor. Fixed frequency operation can be programmed, or synchronized to an external clock source. In applications where (at light loads) variable frequency mode is acceptable, the IC can be programmed to automatically enter PFM (pulse frequency modulation) mode for an additional efficiency benefit.

Synchronous rectification provides excellent efficiency at high power levels, where N- or P- type MOSFETs can be used. At lower power levels (between 10% and 20% of full load) where fixed frequency operation is required, low power mode is entered. This mode optimizes efficiency by cutting back on the gate drive of the charging FET. At very low power levels, the IC enters a variable frequency mode (PFM). PFM can be disabled by the user.

Other features include pulse-by-pulse current limiting, and a low 5-µA quiescent current during shutdown. The UCC39422 incorporates programmable power-on reset circuitry and an uncommitted comparator for low voltage detection. The available packages are 20-pin TSSOP or 20-pin N for the UCC39422, and 16-pin TSSOP or 16-pin N for the UCC39421.

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