Datasheet

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1. General description

The HEF4794B is an 8-stage serial shift register. It has a storage latch associated with

each stage for strobing data from the serial input (D) to the parallel LED driver outputs

(QP0 to QP7). Data is shifted on the positive-going clock (CP) transitions. The data in

each shift register stage is transferred to the storage register when the strobe input (STR)

is HIGH. Data in the storage register appears at the outputs whenever the output enable

input (OE) signal is HIGH.

Two serial outputs (QS1 and QS2) are available for cascading a number of HEF4794B

devices. Serial data is available at QS1 on positive-going clock edges to allow high-speed

operation in cascaded systems with a fast clock rise time. The same serial data is

available at QS2 on the next negative going clock edge. This is used for cascading

HEF4794B devices when the clock has a slow rise time.

It operates over a recommended V

power supply range of 3 V to 15 V referenced to V

(usually ground). Unused inputs must be connected to V

, V

, or another input.

2. Features and benefits

 Fully static operation

 5 V, 10 V, and 15 V parametric ratings

 Standardized symmetrical output characteristics

 Specified from 40 C to +85 C and 40 C to +125 C

 Complies with JEDEC standard JESD 13-B

3. Ordering information

HEF4794B

8-stage shift-and-store register LED driver

Rev. 7 — 16 November 2011 Product data sheet

Table 1. Ordering information

All types operate from





C to +125



Type number Package

Name Description Version

HEF4794BP DIP16 plastic dual in-line package; 16 leads (300 mil) SOT38-4

HEF4794BT SO16 plastic small outline package; 16 leads; body width 3.9 mm SOT109-1

Summary of content (18 pages)

PAGE 1
HEF4794B 8-stage shift-and-store register LED driver Rev. 7 — 16 November 2011 Product data sheet 1. General description The HEF4794B is an 8-stage serial shift register. It has a storage latch associated with each stage for strobing data from the serial input (D) to the parallel LED driver outputs (QP0 to QP7). Data is shifted on the positive-going clock (CP) transitions. The data in each shift register stage is transferred to the storage register when the strobe input (STR) is HIGH.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 4. Functional diagram 3 1 CP STR QS1 9 QS2 10 QP0 4 QP1 5 QP2 6 QP3 7 QP4 14 QP5 13 QP6 12 QP7 11 D CP 10 8-STAGE SHIFT REGISTER 3 9 STR 2 2 1 8-BIT STORAGE REGISTER 15 OPEN-DRAIN OUTPUTS QS1 D OE 4 5 QP0 6 7 QP2 QP1 14 13 QP4 QP3 12 11 QP6 QP5 QP7 OE 15 Fig 1. QS2 001aaf111 Logic symbol Fig 2.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 5. Pinning information 5.1 Pinning HEF4794B STR 1 16 VDD D 2 15 OE CP 3 14 QP4 QP0 4 13 QP5 QP1 5 12 QP6 QP2 6 11 QP7 QP3 7 10 QS2 VSS 8 9 QS1 001aag800 Fig 4. Pin configuration 5.2 Pin description Table 2.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 6. Functional description Table 3. Function table[1] Input Parallel output Serial output CP OE STR D QP0 QPn QS1[2] QS2[3]  L X X Z Z Q6S no change  L X X Z Z n.c.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 7. Limiting values Table 4. Limiting values In accordance with the Absolute Maximum Rating System (IEC 60134). Symbol Parameter VDD supply voltage IIK input clamping current VI input voltage IOK output clamping current II input leakage current IO output current Conditions VI < 0.5 V or VI > VDD + 0.5 V QSn outputs; VO < 0.5 V or VO > VDD + 0.5 V QPn outputs; VO < 0.5 V Min Max Unit 0.5 +18 V - 10 mA 0.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 9. Static characteristics Table 6. Static characteristics VSS = 0 V; VI = VSS or VDD; unless otherwise specified. Symbol Parameter VIH VIL VOH VOL HIGH-level input voltage LOW-level input voltage Conditions IO < 1 A HIGH-level output voltage QSn outputs; IO < 1 A LOW-level output voltage QSn outputs; IO < 1 A IOL HIGH-level output current LOW-level output current Max Min Max 5V 3.5 - 3.5 - 3.5 - 3.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 10. Dynamic characteristics Table 7. Dynamic characteristics VSS = 0 V; Tamb = 25 C unless otherwise specified. For test circuit, see Figure 10. Symbol tPHL Parameter HIGH to LOW propagation delay Conditions CP to QS1; see Figure 6 CP to QS2; see Figure 6 VDD Extrapolation formula Min Typ Max Unit 132 ns + (0.55 ns/pF)CL - 160 320 ns 10 V 53 ns + (0.23 ns/pF)CL - 65 130 ns 15 V 37 ns + (0.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver Table 7. Dynamic characteristics …continued VSS = 0 V; Tamb = 25 C unless otherwise specified. For test circuit, see Figure 10.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 11. Waveforms 1/fclk(max) VI VM CP input VSS tW tW tPLZ tPZL VDD VY QPn output VX VOL tPLH VOH tPHL 90 % VM QS1 output VOL 10 % tTHL tTLH tPLH VOH tPHL 90 % VM QS2 output 10 % VOL tTLH tTHL 001aag222 Parallel output measurement points are given in Table 9. VOL and VOH are typical output voltage levels that occur with the output load. Fig 6.
PAGE 10
HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver VI OE input VM VSS tPLZ tPZL VDD output LOW to OFF-state OFF-state to LOW VOL VY VX outputs enabled outputs disabled outputs enabled 001aag803 Measurement points are given in Table 9. VOL is the typical output voltage level that occurs with the output load. Fig 8.
PAGE 11
HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver VI 90 % input pulse VSS 10 % tf tr VEXT VDD G VI VO RL DUT CL RT 001aag804 Test data is given in Table 10. Definitions for test circuit: DUT - Device Under Test. RL = Load resistance. CL = load capacitance. RT = Termination resistance should be equal to output impedance of Zo of the pulse generator. VEXT = External voltage for measuring switching times. Fig 10. Test circuit for measuring switching times Table 10.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 12. Application information Application example: serial-to-parallel data converting LED drivers. VDD VDD QP7 S2 QP0 D HEF4794B OE STR CP QP0 D HEF4794B OE STR QP7 S2 CP PWM dimmer input CONTROL AND SYNC CIRCUITRY 001aag806 data clock from remote control panel Fig 11. Serial-to-parallel converting LED drivers HEF4794B Product data sheet All information provided in this document is subject to legal disclaimers. Rev.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 13. Package outline DIP16: plastic dual in-line package; 16 leads (300 mil) SOT38-4 ME seating plane D A2 A A1 L c e Z w M b1 (e 1) b b2 MH 9 16 pin 1 index E 1 8 0 5 10 mm scale DIMENSIONS (inch dimensions are derived from the original mm dimensions) UNIT A max. A1 min. A2 max. b b1 b2 c D (1) E (1) e e1 L ME MH w Z (1) max. mm 4.2 0.51 3.2 1.73 1.30 0.53 0.38 1.25 0.85 0.36 0.23 19.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver SO16: plastic small outline package; 16 leads; body width 3.9 mm SOT109-1 D E A X c y HE v M A Z 16 9 Q A2 A (A 3) A1 pin 1 index θ Lp 1 L 8 e 0 detail X w M bp 2.5 5 mm scale DIMENSIONS (inch dimensions are derived from the original mm dimensions) UNIT A max. A1 A2 A3 bp c D (1) E (1) e HE L Lp Q v w y Z (1) mm 1.75 0.25 0.10 1.45 1.25 0.25 0.49 0.36 0.25 0.19 10.0 9.8 4.0 3.8 1.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 14. Revision history Table 11. Revision history Document ID Release date Data sheet status Change notice Supersedes HEF4794B v.7 20111116 Product data sheet - HEF4794B v.6 Modifications: • • Section Applications removed Table 6: – IOH minimum values changed to maximum – added the unit pF for CI HEF4794B v.6 20100901 Product data sheet - HEF4794B v.5 HEF4794B v.5 20100402 Product data sheet - HEF4794B v.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 15. Legal information 15.1 Data sheet status Document status[1][2] Product status[3] Definition Objective [short] data sheet Development This document contains data from the objective specification for product development. Preliminary [short] data sheet Qualification This document contains data from the preliminary specification. Product [short] data sheet Production This document contains the product specification.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver Non-automotive qualified products — Unless this data sheet expressly states that this specific NXP Semiconductors product is automotive qualified, the product is not suitable for automotive use. It is neither qualified nor tested in accordance with automotive testing or application requirements.
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HEF4794B NXP Semiconductors 8-stage shift-and-store register LED driver 17. Contents 1 2 3 4 5 5.1 5.2 6 7 8 9 10 11 12 13 14 15 15.1 15.2 15.3 15.4 16 17 General description . . . . . . . . . . . . . . . . . . . . . . 1 Features and benefits . . . . . . . . . . . . . . . . . . . . 1 Ordering information . . . . . . . . . . . . . . . . . . . . . 1 Functional diagram . . . . . . . . . . . . . . . . . . . . . . 2 Pinning information . . . . . . . . . . . . . . . . . . . . . . 3 Pinning . . . . . . . . . .